Near Record-Breaking Dry Year, Drought Reigns

18 01 2022

Dale C. S. Destin |

It was a near-record-breaking dry year (2021) for Antigua. The year produced a measly island-average rainfall of 600.7 mm (23.65 in), the second lowest on record behind 2015 with 574.5 mm (22.62 in). Officially, 2021 was easily the second most parched year in a series from 1928 and unofficially, since, at least, 1871.

The yellow broken line represents the rainfall anomaly trend, which indicates no significant change to wet (positive) or dry (negative) anomaly.

It was a year reigned by drought from beginning to end, and the reign is likely to go on through the upcoming months. The drought has a firm grip on the weather, being at the most intense category: severe, exceptional by some other standards. The normal annual total is 1156.7 mm (45.54 in), nearly twice the amount measured for 2021.

The rainfall deficit amounts to a whopping 556.0 mm (21.89 in) or 48 percent of the usual total for the year. This is more than the average for the first seven months of a year. Every month accrued a shortfall with the usually wettest month of the year–November, accounting for over 22 percent of the overall rainfall shortage.

This level of waterlessness for a year is extremely rare. There is only a 0.5 percent chance of the island-average being 23.65 inches or lower. This translates to the kind of dryness that has a return period of once in 200 years (1-in-200 years), on average.

Alternatively, there is less than a 10 percent chance of such harsh weather reoccurring in the next 20 years. One is, at least, twice as likely to see a hat-trick in a cricket match than experience the likes of such lacklustre annual rainfall.

268Weather accurately predicted a drier than usual year was likely. As early as May 2021, we indicated a 46 percent chance of below normal rainfall. The chance rose to 58 percent in June and peaked at 61 percent in August. There was also a peak of 19 percent for the year to rank among the top 10 driest.

The usually wettest consecutive pair of months, October-November, almost literally produced a speck in the bucket. The frequently rainiest duo was the record driest with the trivial amount of 63.8 mm (2.51 in) with each month recording less than an inch-and-a-half of rainfall for the first time, on record. Combined, the shortfall for the months accounted for 45 percent of the year’s deficit. The previous lowest for this period was 89.7 mm (3.53 in), in 1983.  

The last quarter (October-December) was also the driest on record, dating back to 1928. The total of 127.3 mm (5.01 in) shattered the previous record of 143.0 mm (5.63 in), for the last three months of the year, set in 1983. Usually, this period precipitates 397.5 mm (15.65 in), over thrice what actually fell.

It was essentially a year without a wet season (July-December). The dry season pretty much went on and on, for the whole year, resulting in a record-breaking dry wet season. The season’s total of 396.0 mm (15.59 in) retired the previous driest wet season of 1983, which accumulated 405.6 mm (15.97 in). Cumulatively, the third and fourth quarter rainfall represented just 53% of the normal amount of 746.8 mm (29.40 in). A typical dry season (January-June) averages more rainfall than occurred for the 2021 wet season.

While the island on a whole had near-record-breaking low rainfall, parts of the country actually had record dryness. Coolidge, in northeast Antigua, had a record low rainfall of 469.6 mm (18.49 in), crushing the previous record of 554.0 mm (21.81 in) set in 2015. This represents only 47 percent of the normal annual total of 1000.8 mm (39.40 in). This kind of rainfall scarcity occurs only once every 333 years, on average, or a less than 10 percent chance of occurring in the next 35 years or the next generation.

It is unclear as to what was responsible for this nearly unprecedented dryness. The usual culprit: El Niño was not only absent but his sister: La Niña, usually the rainmaker, was present, yet to little avail. The dryness may have been mainly the result of a consistent stream of dry and dusty air from the Sahara Desert along with a cooler than usually tropical North Atlantic.

There is the saying: “If rain does not fill a [water] drum, dew is not going to fill it.” Meaning, if the wet season did not end the droughts, particularly the hydrological and socioeconomic ones, how can the dry season, which we are in, do so? It can’t; hence, the sufferation from insufficient rainfall could continue through the next six months.

The last 10 years have been the driest decade for Antigua. Five of the last 10 years have had below normal rainfall with 2015 and 2021 ranking one and two, on record. Only one year (2020) has had above normal rainfall since 2011.

Other Caribbean islands are having similar challenges with rainfall or lack thereof. For example, the Henry Rohlsen Airport in St. Croix was said to be on track, in December, to record its third driest year, on record dating back 58 years. A number of other parts of the Caribbean were also on the way to record rainfall ranking among the top 10 lowest.  

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Drought is Back

14 03 2021

Dale C. S. Destin |

Drought is back for Antigua. A slight meteorological drought is present as of the end of February. It is most likely to get worse over the next three months, as below normal rainfall is forecast by most models.

The rainfall for winter – December to February (DJF) 2020-2021, was 149.1 mm (5.87 in). This total is deemed below normal and beneath the drought threshold. Usually, DJF yields 225.8 mm (8.89 in) of rainfall, on average; hence, there is over a 75 mm (over 3 in) deficit or a 34 percent shortfall.

Rainfall for Antigua for the period December 2020 to February 2021. Picture in the background is Potworks Dam as of March 3, 2021 courtesy Karen Corbin of the Humane Society.
Rainfall for DJF is well below the slight or worse drought threshold, nearly at moderate drought. Rainfall for this period for Antigua shows no significant trend (black dashed line). Excess rainfall tends to be more extreme than drought rainfall.

The month that is mainly responsible for the scarcity in precipitation is January, which got only 41 percent of the normal amount of 67.3 mm (2.65 in). The rainfall for February was also lower than usual, accounting for 73 percent of the normal amount of 50.0 mm (1.97 in). The rainfall for December was near normal.

The two-month rainfall for January-February (JF) of 63.8 mm (2.51 in) is the lowest since 2001. Thus, the very dry start to the year continues. With this JF ranking the eighth driest on record, only seven other years have had a drier start on record dating back to 1928.

It normally takes a few months for the effects of a meteorological drought to descend to a hydrological drought and cause potable water issues. However, the effects are already manifesting themselves in the lowering of water in catchments. Yesterday, the APUA Business Unit Water Manager – Ian Lewis, said on Observer Radio News that the country has about three to four months of surface water remaining, at current extraction rate.  

We were last in a drought April to October last year. This was a severe drought that was more than meteorological; it resulted in surface catchments transforming into mud patches and then to grass lands. It is unclear, at this stage, whether there will be a repeat of similar rainfall absence this year.

The dry conditions last year, resulted in water rationing and almost a 100 percent reliance on desalinated water. Ian Lewis has already indicated that the absence of notable rainfall over the coming months would usher in return of the water conservation schedule better known as water rationing.

Antigua is not alone in experiencing notable rainfall deficits in the wake of winter. Much of the Caribbean is suffering a similar fate, from a drier than usual dry season, thus far. Short and long-term droughts are evolving across a number of islands and there is the potential of several others joining this drought-list.

Rainfall anomaly (departure form average) in mm for the Caribbean, based on CMORPH data

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High Surf Events This Week

27 01 2021

Dale C. S. Destin|

Much higher than usual surfs are expected to pound the shorelines of much of the Eastern Caribbean. One episode is getting underway and will last for 24 to 36 hours. A second episode will occur over the weekend. These surfs are expected to cause the threat level to rise to high for life, livelihood, property and infrastructure of those using or living on the affected coastlines and there is the potential for extensive impacts.

Past Surf Event - James Beach
Fort James Beach, Antigua, During a Past High Surf Event

Based on the expected swells, which will transition to surfs when they reach near shore, surfs over 3 metres (10 feet) are projected to take place at times. Advisories and warnings are expected for a number of islands.

The first hazardous surf event is likely to subside by Friday for most areas but rise again over the weekend. The second episode of dangerous surfs will start across the Bahamas on Friday and reach the Eastern Caribbean by Saturday.

It is the surf season, when powerful winter storms come off North America, often packing the equivalent of tropical cyclone winds, sometimes reaching winds equal to hurricane strength. These systems frequently track across the “pond” from the United states to Europe, all the while pushing large swells toward the Caribbean and elsewhere, resulting in hazardous conditions along mainly north and east-facing coastlines of the islands.

5-day plot - Swell Height at 41044
High Swells Heading for the Eastern Caribbean to Become High Surfs or Breaking Waves Near Shorelines

The coming high surf events will be due to a series of winter storms. The one that will cause the surf episode over the weekend will be a storm, whose pressure drop by 24 millibar or more in 24-hours. Such winter storm systems are called bomb-cyclones.

There is no strong wind concern for any of the islands. The concern is for mainly Atlantic coastlines for especially the Northeast Caribbean – from Puerto Rico to the northern Windward Islands.

Potential impacts include but not limited to:

  • loss of life;
  • injuries to beachgoers;
  • salt-water intrusion and disruptions to potable water from desalination
  • disruptions to marine recreation and businesses;
  • beach erosion and
  • sea water splashing onto low lying coastal roads.

All should be very wary about bathing in the impacted areas. Personally, although I can swim, I do not plan to go to the beach during the times the surfs are expected to be higher than usual. Going rock fishing is not advisable.

The concern is not only for high surfs, but also rip currents. Rip currents are powerful channels of water flowing quickly away from shore, which occur most often at low spots or breaks in the sandbar and near structures such as groins, jetties and piers. High surf events make for very conducive conditions for rip currents.

If caught in a rip current, relax and float. Don’t swim against the current. If able, swim in a direction following the shoreline. If unable to escape, face the shore and call or wave for help.

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Extreme Winds and Seas to Usher in the New Year

28 12 2020

Dale C. S. Destin |

Extreme wind and marine events are forecast for this week across the northeast Caribbean, including Antigua and Barbuda. The howling wind event will take place Thursday – NEW YEAR’S EVE, through Saturday – January 2, whereas the life-threatening marine event will take place New Year’s Eve night through Sunday – January 3. Warnings and advisories for strong winds, rough seas and high surfs will be required for most islands.

Northeast Caribbean: Estimated max 3-second gusts; max sustained 10-minute winds; average of the top 10% of significant wave heights and average of top 10% of swells

The angry winds and seas could cause notable socio-economic impacts to the islands. Similar actions by nature, earlier this year, caused ships to turn away from Antigua and Barbuda and cancelled ferry services. There were also reports of LIAT aborting landings in some islands; banana trees being downed in some countries and power outage in some areas.

The kick-off of these unwelcome but not unusual events is expected on Thursday. The pressure gradient will rapidly and significantly steepen, which will become evident by the closeness of the isobars – lines of equal pressure, on our weather maps. The closer the isobars, the steeper the pressure gradient, the stronger the winds and vice versa.

Gale-force gusts, the equivalent to tropical storm-force gusts, are likely – gusts exceeding 78 km/h (over 48 mph). Otherwise, the winds will frequently be above 40 km/h (over 25 mph). The maximum sustained 10-minute wind speeds will likely reach around 50 km/h (31 mph), whereas the maximum sustained 1-minute winds will reach around 56 km/h (35 mph). The strongest winds are forecast for New Year’s Day, especially across open waters, windward coastal areas and elevated places. The prevailing wind direction will be northeast.

Visualization of wind gusts (shaded) wind direction (short solid lines) and isobars (long solid lines with numbers – pressure in millibars) – December 31 2020 to January 4 2021

As the winds go, so go the seas. The tumultuous winds will cause the seas to rise and become extremely threatening – very rough in open waters on Thursday through Sunday. Significant wave heights could peak at or above 4 metres (over 13 feet), locally exceeding 5 metres (near 17 feet). The highest seas are also expected on New Year’s Day. These seas will be non-navigational for small craft and even some non-small-craft operators.

Significant wave heights according to the ECMWF WAM Model – December 31 2020 to January 5 2021

High swells and surfs (breaking waves) are also forecast for Sunday. Swells in excess of 2.5 metres (over 8 feet) and surfs in excess of 3 metres (over 10 feet) are likely. These breaking waves will make for very dangerous conditions for beachgoers and others using the coastlines.

The events will make for a high threat to the life and livelihood and property and infrastructure of mariners and users of the nearshore areas. There is also the potential for extensive impacts including the following:

  • Loss of life
  • Injuries
  • Damage or loss of boats and fishing equipment
  • Saltwater intrusion and disruptions to potable water from desalination
  • Coastal flooding from sea water splashing onto low lying coastal roads
  • Sea search and rescue disruptions
  • Cancellations to transportation (especially by sea)
  • Scarcity of sea food
  • Disruption or cancellation to sporting and recreation events (especially marine activities)
  • Businesses and economic losses

To be safe, mariners should stay in or near port and beachgoers should stay out of the waters for affected coastlines. Also, residents should secure light and loose objects, which can be blown away, and caution should be taken when driving. The anticipated blustery winds could make some outdoor activities uncomfortable, if not outright dangerous. These winds can also create dangerous fallen or blowing objects.

The turbulent winds will unsettle the atmosphere, resulting in brief heavy showers. However, rainfall accumulations will only be of minimal concern, at most.

These events will affect virtually the entire Caribbean Basin, at different times. They will start across the Bahamas and the Western Caribbean on Tuesday and reach the northeast Caribbean on Thursday. Then, they will spread across the southern Caribbean by Friday – New Year’s Day. The extreme events will come to an end by Sunday, January 3, 2021, although seas will likely still be hazardous for some areas, beyond Sunday.

At times, it may feel like there is a tropical storm in the area, but I can ashore you that there is none. The hurricane season remains over.

Check and monitor your local forecasts, from your national weather service, for details specific to your location. This is a relatively broad scale view; hence, the numbers WILL change either way.

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The Hurricane Season in November

9 11 2020

Dale C. S. Destin|

November hurricanes are almost unheard of for Antigua and Barbuda. I say almost because we have an exception – Hurricane Lenny of 1999. In 169 years of record dating back to 1851, Lenny is our (Antigua and Barbuda and the rest of the Eastern Caribbean) only November hurricane.

This image has an empty alt attribute; its file name is image-9.png
Lenny south of the US Virgin Islands. Credit Wikipedia
The Track of Hurricane Lenny – November 13-23, 1999

Prior to Lenny, we in the Eastern Caribbean, have not had a November named storm (tropical storm or hurricane) since 1896 – over 100 years before Lenny. November named storms amount to eight for the Eastern Caribbean, four of which affect Antigua, with Lenny being the only hurricane on record.

Lenny impacted Puerto Rico, the Virgin Islands, the Leeward Islands, the Windward Islands and even as far away as Colombia. It killed at least 17 people and caused over US$785 million in damage, a lot due to flooding.

The Atlantic Basin, including the Caribbean, averages one November named storm per year, one hurricane every other year and a major hurricane – Category 3 or higher intensity, every 10 years; this is based on the current climatological period of 1981-2010.

To date, no Category 5 hurricane has had its origin in November, based on the record. There was an unnamed Category 5 hurricane in 1932 that formed in October but reach Category 5 status in November; however, storms are credited to the month in which they were formed or originate in.

The probability of Antigua and Barbuda being impacted by a storm or hurricane, in November, is around 3 percent, based on the 1981-2010 base period. This translates to, at least, a storm or hurricane every 33 years, on average. With Lenny being our last hurricane, we are not due another hurricane in November until around the year 2032. The same is true for a major hurricane, in November.

The probability of a storm or hurricane impacting the Eastern Caribbean, in November, is around 6 percent or one every 16-17 years. This increases to around 12 percent or one every 8-9 years for the Central Caribbean and 28 percent or every 3-4 years for the Western Caribbean.

November Hurricane Climatology
The zones of origin and tracks of named tropical cyclones (tropical storms and hurricanes) in November.

The last November hurricane for the Caribbean was Otto of 2016. It formed across the southwest Caribbean Sea and impacted Nicaragua and Costa Rica, then crossed over into the Pacific Ocean. It killed 23 people and caused damage amounting to over US$192 million. It is the last Atlantic tropical cyclone to crossover to the Pacific and only the 14th to have done so.

Infrared satellite loop of Hurricane Otto making landfall as a Category 3 hurricane in Nicaragua on November 24. Credit Wikipedia.

From 1851 to 2019, November has produced a total of 92 named storms of which 56 were hurricanes and 6 were major hurricanes. For the climate period 1981-2010, there have been 20 named storms, 14 hurricane and 3 major hurricanes.

 November 1-10 Tropical Cyclone Genesis Climatology
Click for large image
 November 11-20 Tropical Cyclone Genesis Climatology
Click for large image
 November 21-30 Tropical Cyclone Genesis Climatology
Click for large image

It must always be noted that there are likely named tropical cyclones (tropical storms and hurricanes) that were missed prior to the satellite era – before the mid-1960s.

November 2005, 1961 and 1931 holds the record for the most named storms for the month – three. Further, 2001, 1994 and 1980 holds the record for the month for hurricanes – two. Meanwhile, no November on record has had more than one major hurricane in a year and only six have had a major hurricane – 2016, 2008, 1999, 1985, 1934 and 1912.

What will this November bring? Given that each month of this hurricane season has produced, 1.5 to 2.5 times its average number of named storms and that up to 32 named storms are forecast to the year, with 28 gone, this November could end up producing up to two storms, with one becoming a hurricane.

It is not over yet, but the end is nigh – November 30. Usually, November is a low stress month for hurricanes; however, this is 2020 – stay prepared!

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Busy Week Ahead for the Caribbean

16 08 2020

Dale C. S. Destin |

Looks like the Caribbean is set for another busy week. There is the potential for two tropical cyclones – tropical depressions, tropical storms or hurricanes, impacting the area.

Tropical Disturbances AL97 (near the Caribbean) and AL96 (near Africa)

It is the start of a new week but the continuation of a record-breaking hurricane season, which could add two more storms to its tally, in days. There are two new disturbances between Africa and the Caribbean, taking aim at the islands.

Satellite picture animation showing the locations of the distrubances

It is uncertain as to whether these disturbances will become tropical cyclones, where they will go and what hazards, they will bring to the area. However, at this time of the year, most disturbances do develop into tropical cyclones, as conditions are generally conducive, like they are currently, bar the dry and dusty Saharan air.

Today, we saw the end of Tropical Storm Josephine, which threatened the area but eventually passed a safe distance north of all the islands.

Tropical Storm Josephine passing by on Saturday afternoon, 15 August, 2020

With Josephine gone, all attention is now on Disturbances AL96 and AL97. They both have a 50 percent chance of formation. And they both have tracks that take them through the Caribbean.

The second of the two systems, AL96, appears to be more of a future threat to the Caribbean, particularly the Leeward Islands. AL97 is perhaps moving too rapidly for much development to take place before reaching the Eastern Caribbean tomorrow; however, it is forecast to slow down in the Caribbean Sea where it will encounter favourable conditions for formation Wednesday.

Most available models have AL97 becoming a tropical storm in 48 hours – Tuesday night/Wednesday
Most available models have AL97 going through the southern Caribbean, at most, as a Tropical Depression

The gold standard of models – the ECMWF IFS or European model is very sweet on AL96. It gives it a relatively high chance of becoming a tropical storm and track towards our “neck of the woods” – the Leeward Islands this upcoming weekend. This week could end similarly to the one just gone – with us under a Tropical Cyclone Alert or worse.

Already for the season, there have been 11 named storms, the most to have ever occurred this early in the year, with the more active half of the hurricane season just getting started. With half of the season to go, only 48 out a total of 169 seasons, dating back to 1851, has seen more storms.

Be prepared! Based on the forecast, the season is likely to produce, at least, nine more named storms, five more hurricanes and three major hurricanes. It is likely to be a very long season.

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Another Bomb Cyclone to Push Impactful Swells to the Caribbean

7 03 2020

Dale C. S. Destin|

Another bomb cyclone is expected to cause another episode of  large and damaging swells across much of the Caribbean Basin. The impactful swells will start to reach the shorelines of the Basin this Sunday. These swells are forecast to reach a few metres and break at higher heights on coastlines.

Visualization of northerly swells forecast to come to the Caribbean from the bomb cyclone

Swells will rise to at least 3 metres (at least 10 feet) across most of the Atlantic waters of the islands. These swells will produce even higher surfs or breaking waves. Surfs could be as much as twice the height of the incoming swells, depending on the bathymetry/topography of the near shore seafloor. The swells and surfs are expected to cause beach closures, as swimming conditions will become quite hazardous. Other impacts include:

  • major beach erosion;
  • flooding of some low-lying coastal roads;
  • disruptions to marine recreation and businesses;
  • disruptions to potable water from desalination;
  • damage to coral reefs and
  • financial losses.

Advisories and warnings will be required for much of the upcoming week. Please be guided by the bulletins coming out of your national weather services.

The event will be cause by an average extratropical cyclone transitioning to a bomb cyclone – a drop of 24 millibars/hectopascals or more in 24 hours or less. This will result in the system developing gale-force or tropical-storm-force winds that will push large waves to the Caribbean.

8 pm local time Friday, 6 March, 2020: Bomb cyclone with centre marked by the X near the red L, just off the coast of New York
Visualization of Bomb Cyclone 6 am UTC Saturday or 2 am local time Saturday, 7 March, 2020: Pressure – shaded areas, isobars – circular fixed lines (1012, 1008, 1004 etc.) and wind direction – lines circling inwards toward the centre of the bomb cyclone
Visualization of Bomb Cyclone 6 am UTC Saturday or 2 am local time Saturday, 7 March, 2020: Wind speed – shaded areas, wind direction – lines circling inwards toward the centre of the bomb cyclone

The cyclone will remain very far away from the area – thousands of miles; however, it will have a significant impact on the region, by way of swells transforming into high surfs on our shores. Associated with these surfs are potentially very powerful and life-threatening rip currents.

The first set of these swells will reach the Bahamas on Sunday; the northeast Caribbean, including Antigua and Barbuda, by Monday and the rest of the Eastern Caribbean by Tuesday. The event will likely last three days from its start time. So, for the northeast Caribbean, its Monday through Thursday.

As usual, the impacts on shorelines will not be the uniformed. The impacts will depend on the depth and the natural shelter of the coastal waters. Northern islands with moderately sloping, shallow, northern and or north-facing shorelines are expected to see the highest swells and surfs, and hence; the greatest impacts.

This event is not expected to be worse than the last notable one which took place in January 2020. Notwithstanding, it will not be your “garden variety” event.

The event will also be felt along the East Coast of the United States. The same powerful cyclone will also cause extreme weather across Ireland, the United Kingdom and northern Europe next week.

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Bomb Cyclone to Push Damaging Swells Across the Caribbean

16 01 2020

Dale C.S Destin|

The Caribbean Basin is about to see another round of large and damaging swells reaching its shorelines starting Saturday, from a bomb cyclone. Swells are forecast to exceed 3.5 metres (12 feet) and break at higher heights, as surfs, on coastlines. This is likely to be the biggest swell event since Swellmageddon of March 2018.

Animation of bomb cyclone, east of Canada, with pressure pattern, wind speeds and directions, as forecast by the Global Forecasting System (GFS) Model. Time in UTC

The event will be kicked off by a relatively inconspicuous low-pressure system (LPS), currently over the northeast United States. The LPS will go through explosive development (bombogenesis) over the next 24 hours and become a ginormous and powerful bomb cyclone (extratropical cyclone) over the northwest North Atlantic, with hurricane-force winds.

Although this system will form over 3220 km (2000 miles) away, it will have a significant impact on the region, through its strong winds pushing unusually high waves to our shores. The first set of these swells will reach the Bahamas on Saturday; the northeast Caribbean, including Antigua and Barbuda, on Sunday and the Guianas on Monday. The event will likely last three days from its start time. So, for the northeast Caribbean, its Sunday through Tuesday.

Animation of swells forecast to move across the region from the bomb cyclone, as predicted by the European Centre for Medium-Range Weather Forecasts (ECMWF) wave model (WAM). Time in UTC.

Swells will rise to to in excess of 3.5 metres across most of the Atlantic waters of the islands. There swells will produce even higher surfs or breaking waves. These surfs could be as much as twice the height of the incoming swells, depending on the bathymetry/topography of the near shore seafloor. This is expected to cause beach closures, as swimming conditions will become quite hazardous. Other impacts include:

  • major beach erosion;
  • flooding of some low-lying coastal roads;
  • disruptions to marine recreation and businesses;
  • disruptions to potable water from desalination;
  • damage to coral reefs and
  • Financial losses.

Advisories and warnings will be required for the weekend and or the first half of next week. The event will also be felt along the East Coast of the United States, Canada, Greenland, Iceland, the United Kingdom and Norway. Rowers of the Talisker Whisky Atlantic Challenge will also be negatively impacted, exponentially increasing the challenge of an already very challenging race.

High surf warnings or advisories will be required for coastal areas for much of the Caribbean this weekend and into the middle of next week

The impact on shorelines will not be the same everywhere. Depending on the depth and the natural shelter of the coastal waters, the impact will be different. Moderately sloping, shallow, north and or north-facing shorelines are expected to see the highest swells and surfs.

The bomb cyclone will go from a central pressure of 1004 hectopascals (hpa) (which is the same in millibars) to around 968 hpa in 24 hours and to a minimum of 955 hpa in 48 hours, just east of Newfoundland and Labrador, Canada. This represents an explosive drop of 59 hpa – more than one hpa per hour; thus, meeting the definition of a bomb cyclone – a drop in pressure of an extratropical cyclone of at least 24 hpa in 24 hours or less.

By Saturday, this weather bomb will be packing Category 1, hurricane force winds – 119 to 153 km/h (74 to 95 mph). These are the winds that will, in turn, generate large waves that will traverse the Atlantic and pound the shorelines of the Caribbean, inundating some low-lying coastal areas.

Of course, the hurricane force winds do not even have the remotest of chance of reaching the Islands; however, some of the wind energy, transferred into the seas will reach us in the form of ocean waves – ground swells. As you may know, waves do not transport water; they transport energy, which can de destructive when they break on shorelines.

Animation of wind directions and speeds forecast to impact the region, as predicted by the ECMWF Integrated Forecasting System (IFS) Model. Time in UTC.

Talking about winds, they are expected to surge – getting to the general range of 25 to 45 (16 to 28 mph), across the region again late Saturday and likely continue into Monday. Storm-force gusts to near 65 km/h (40 mph) are expected, especially in showers. Thus, both high wind advisories and small craft warnings are highly possible late Saturday through Monday morning.

Our (Caribbean) weather will also become wet again over the weekend and into midweek. There is a very high chance of occasional brief showers, as the high winds will destabilise the atmosphere via mixing and low-level convergence.

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Strong Howling Winds to Continue to Impact the Caribbean

11 01 2020

Dale C.S. Destin, updated January 12, 2020 |

Strong howling winds are expected to continue across much of the Caribbean Basin through Tuesday. These huffing and puffing, big bad wolf winds are causing notable socio-economic impacts to the islands.

As the winds go up, so also do the seas; hence, hazardous seas have engulfed the region – from the Bahamas to the Guyanas, including the Caribbean Sea.

The winds have risen to the range of 29 to 52 km/h or (18 to 32 mph) over land and are expected to persist until Tuesday. Further, gusts as high as 80 km/h (50 mph) are possible for some areas. Over the Caribbean Sea, the winds are forecast to be stronger than some places over land. One such area is between Jamaica and Columbia, where sustained winds – 70 km/h (44 mph), are forecast. With respect to land, the highest sustained winds are forecast for the Eastern Caribbean.

The blustery winds will cause the seas to remain very angry with significant wave heights of 2.5 to over 4 metres (8 to 14 feet) and occasionally reaching over 5 metres (18 feet). There is an area between Jamaica and Columbia where the significant wave heights are predicted to be over 5 metres (18 feet), occasionally reaching 7 metres (23 feet).

Over the past 24 hours, above normal swells, from distant strong winds, have added to the hazards across the area. So, not only there are concerns for high winds and hazardous marine conditions in open waters, there is now also a concern for the impact of life-threatening surfs (breaking waves) along, mainly northern and north-facing shorelines; hence, a high surf advisory has or will be required for most islands. Already, a high surf advisory is in effect for much of the Caribbean.

Beachgoers should be extremely cautious; bathe only where lifeguards are present or the sheltered, less affected beaches, mainly to the south. See the bulletins from your national weater service for detail and specific guidance for you local.

Such conditions are very conducive fo rip currents – powerful channels of water flowing quickly away from shore, which occur most often at low spots or breaks in the sandbar and near structures such as groins, jetties and piers. If caught in a rip current, relax and float. Don`t swim against the current. If able, swim in a direction following the shoreline. If unable to escape, face the shore and call or wave for help.

As a result of the weather, more so the strong winds, three cruise ships had to abort berthing at the St. John’s Harbour in Antigua. These, I am informed, were The Anthem of the Seas, Norwegian Dawn and Crown Princess. Ferry service between Antigua and Montserrat has been cancelled until Thursday. The have also been aborted attempts by LIAT to land in Dominica. There are also reports of downed banana and other trees in the Windward Islands and Trinidad and Tobago, and there have been power outage in the British Virgin Islands and Trinidad and Tobago attributed to the strong winds.

Thus far, the highest winds (10-minute sustained and gusts) have been observed at:

  • Grantley Adams International Airport (GAIA), Barbados;
  • George F.L. Charles Airport (GFLCA), St Lucia and
  • Norman Manley International Airport, Jamaica.
The winds by the numbers. One mph = 1.61 km/h. Multiply 10-minute sustaned winds by 1.11 and 1.40 to get 1-minute sustained winds and 3 second gusts respectively. *Harper et al. 2010 is the World Meteorological Organization (WMO) standard.

Looking at the winds by the numbers. Speeds of 39 mph or more are storm-force or gale-force winds, gusts in this case. However, when dealing with tropical cyclones, categorization is based on a maximum 1-minute sustaned wind speed. To convert from 10-minute wind speeds to 1-minute wind speeds, multiply by 1.11. Thus, parts of Barbados, Jamaica and St. Lucia had sustained storm-force windsstorm conditions (35×1.11 = 39 mph or 63 km/h). However, note that there are no tropical cyclones in the area.

Winds blow because of the differential of pressure across the Earth’s surface. The higher the horizontal differential or the higher the pressure gradient, the stronger the winds. The strong winds, over the next several days, will continue to be due to a very steep pressure gradient. The pressure will be that steep largely due to a 1042 millibar high-pressure system moving off the US east coast.

Pressure pattern forecast for 2 am Saturday, January 11, 2020
The ususal pressure pattern across the North Atlantic for January. Note that the usual difference of pressure between Bermuda High and the Caribbean is around 6 to 8 mb.

Immediately above is the usual pressure pattern for the North Atlantic. Note that the usual difference in pressure between the Bermuda High and the Caribbean is around 6 to 8 millibars. However, compare the graphic below to the one above and you will observed that the difference in pressure between the Bermuda High and the Caribbean (at 2 am, Sat, 11 Jan 2020) was 20 to 24 millibars. Thus, the pressure difference and gradient were two to four times higher that usual or 200 to 400% of normal; hence, the very strong winds.

North Atlantiuc surface chart – 2 am, Saturday, 11 January 2020

The highest and most dangerous waves will take place across the waters of the western Caribbean – between Jamaica and Columbia. This area will also experience the strongest winds – 51 to 64 km/h (32 to 40 mph), gale-force/storm-force winds, with gusts in excess of 96 km/h (60 mph).

Advisories and or warnings to mariners have been issued by a number of islands, including Antigua and Barbuda, Puerto Rico and Barbados.

As a small craft operator, if an advisory is issued – inexperienced mariners, especially those operating smaller vessels should avoid navigating in these conditions. If a small craft warning is issued – you should stay in or very near port.

Potential impacts from this hazardous sea event include injuries or loss of life, damage or loss of boats and fishing equipment and disruption to sea transportation. Other possible impacts comprise of:

  • disruptions to sea search and rescue;
  • scarcity of seafood;
  • disruptions to off shore marine recreation and businesses;
  • business and economic losses.

On the other hand, the strong winds could result in further disruptions to transportation and outdoor sporting activities, soil erosion, vehicular accidents and financial losses.

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Another Windy, Rough and Wet Week Ahead

16 12 2019

Dale C. S. Destin|

Rough Seas – Photo by Getty Images

This is a new week, but similar weather is expected to last week’s – windy and wet with rough seas. Winds are expected to surge over the next 24 hours, resulting in the winds becoming fresh to strong by Monday night. This will in turn cause hazardous seas and wet weather across much of the Caribbean Basin, including Antigua and Barbuda.

The winds and seas will be a threat to the life and property of mainly mariners. Some outdoor activities, on land, could also become dangerous.

By late Monday, the winds will rise to the range of 26 to 42 km/h (16 to 26 mph) with stronger gusts . It is expected that the winds will gusts to near storm-force/gale-force – 63 km/h (39 mph), mainly over open waters, exposed coastal areas and elevated terrains.

Given the expected winds, a high wind advisory may be required, particularly for the areas listed above. If a high wind advisory is issued, residents should secure loose and light outdoor items, which can be blown away, and caution should be taken when driving.

As the winds go, so go the seas – as the winds go up, the seas will go up also and become hazardous. Seas (significant wave height – SWH) are forecast to rise to a range of 2 to 3 metres (7-10 feet) with the potential extreme (10% chance) of reaching over 3.5 metres or 12 feet. Notwithstanding, the potential extreme SWH, seas are expected to occasionally reach near 4 metres (13 feet).  

Recall that seas are given as SWH, which is the average height of the highest 1/3 of the waves. Individual waves may be twice the SWH.

Given the expected height of the seas, particularly wind waves, a small craft warning is expected to go into effect for much of the waters of the Eastern Caribbean Monday night through Thursday morning. An advisory is in effect and one will be in effect after the warning.

Recall that a small craft warning generally means that wind speeds of 38 to 61 km/h (24 to 38 mph) and or seas of 9 feet or greater are expected to produce hazardous wave conditions to small crafts. If or when a warning is issued, small craft operators should stay in or near port and safeguard their vessels.

Impacts possible/likely/expected from hazardous seas include the following:

  • Loss of life;
  • injuries;
  • sea search and rescue disruptions;
  • disruptions to sea transportation;
  • scarcity of sea food;
  • damage or loss of boats and fishing equipment;
  • disruptions to marine recreation and businesses
  • and economic losses. 

Other impacts from the high winds, apart from hazardous seas, include:

  • injuries;
  • soil erosion;
  • localized disruptions of businesses;
  • disruption to outdoor and sporting activities;
  • disruption of transportation (air and especially sea) and
  • vehicular accidents and financial losses.

Wind of this strength could make some outdoor activities uncomfortable, if not outright dangerous. High winds can create dangerous fallen or blowing objects.

The strongest winds and the highest and most dangerous seas will take place on Tuesday. The highest seas will take place in the Atlantic waters of the islands.

The strong winds will be due to a very steep pressure gradient. Think of the pressure gradient like a hill and the wind as a car. The steeper the hill the faster the car will roll down the hill and vice versa. On a weather map, the steepest gradient and strongest winds are where the lines of equal pressure (isobars) are closest.

The higher than usual winds will destabilize the atmosphere, resulting in brief passing showers from time to time. Possible rainfall total for the week across the Eastern Caribbean is 25 to 150 mm (1-6 inches). The highest totals are likely across the southern Caribbean.

Last week, similar type weather took place. The area had fresh to strong winds with gusts in excess of 48 km/h (30 mph). The whole of the Eastern Caribbean had wet weather with some areas experiencing rainfall in excess of 150 mm (6 inches).

Seas will subside from warning to advisory levels by Thusday; however, it is unclear as to when seas will return to safe levels – when no warning, advisory or caution is required.

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Relief Unlikely for Drought Stricken Areas of the Eastern Caribbean

1 02 2019

Dale C. S. Destin |

According to the latest Caribbean Climate Outlook Newsletter (CCON), Anguilla south to Trinidad, including Barbados will most likely experience below normal rainfall for the upcoming season – February to April (FMA). This means that any drought occurring in these islands will likely get worse or remain unchanged.

Over the period October-December, severe droughts have developed or are ongoing across parts of a number of islands to include:

  • Hispaniola;
  • Guadeloupe;
  • Martinique and
  • Barbados.

A scarcity of rainfall in 2018 and mostly likely lower than usual rainfall through April 2019 have led to long-term droughts or concern of long-term droughts in many islands, according to the February to April Newsletter. These include:

  • Antigua and Barbuda
  • Cayman;
  • NW Cuba;
  • Northern Dominican Republic;
  •  Grenada;
  • Martinique;
  • Northeast Puerto Rico and
  • Tobago.

CCON blames the likelihood of below normal rainfall for FMA on a weak El Nino, which is forecast to last through the period.

El Nino could last through the wet season, which is bad news, as it normally causes reduced rainfall and or droughts across most of the Caribbean – particularly in the wet season. 

El Nino refers to the unusual warming of the central and eastern tropical parts of the Pacific Ocean, which historically occurs every 2 to 7 years and lasting for 9-12 months, sometimes longer. It generally has the effect of causing drier than usual weather across the Eastern Caribbean.

We are in the dry months of the year. Traditionally, not a lot of rain fall across the Caribbean during FMA. It is a part of the heart of the dry season for the vast majority of the region, with only January-March being drier, as a whole.

The usual rainfall totals: February to April

The dryness of the season is normally especially evident across Aruba, Curacao and Bonaire – the ABC Islands, who have average rainfall for this period of below 75 mm (less than 3 in). It is not unusual for these islands to see zero rainfall during these months, in some years.  

Click here or the graphic above to read the full Newsletter

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Strong Winds and Hazardous Seas to Impact Parts of the Caribbean

22 01 2019

As the winds go, so go the seas. As the winds go up the seas will go up and become hazardous across the Bahamas, Cuba and Jamaica, in the western Caribbean, to around Anguilla in the northern Leeward Islands.

Hazardous Seas – Credit UCAR

The winds and wind waves have already started to pick up across the islands mentioned above, particularly the western Caribbean. The winds will eventually get to the range of 34 to 53 kmh (21 to 33 mph) through Thursday. Consequently, seas will become hazardous with wind waves of 2.5 to 3.5 metres (8 to 12 ft), occasionally reaching 4.5 metres (15 ft).

The highest and most dangerous waves will take place across the waters of the western Caribbean, where the winds will be the strongest. Outside of the islands listed above, including Antigua and Barbuda, the wind waves will unlikely reach 2.5 metres (8 ft), as the winds are not expected to get sufficiently high.

Advisories and or warnings to mariners, particularly small craft operators, will be required and already Puerto Rico and the Cayman Islands have issued such.

As a small craft operator, if an advisory is issued – inexperienced mariners, especially those operating smaller vessels should avoid navigating in these conditions. If a small craft warning is issued – you should stay in or very near port.

Potential impacts from this hazardous sea event include injuries or loss of life, damage or loss of boats and fishing equipment and disruption to sea transportation. Other possible impacts comprise of:

  • disruptions to sea search and rescue;
  • scarcity of seafood;
  • disruptions to off shore marine recreation and businesses;
  • business and economic losses.

On the other hand, the strong winds could result in disruptions to air transportation and outdoor sporting activities, soil erosion, vehicular accidents and financial losses.

As the winds go, so goes the seas; however, as the pressure gradient goes so go the winds. The winds will become strong because the pressure gradient will become quite tight across the northern islands. Think of pressure gradient like a hill and the wind as a car. The steeper the hill the faster the car will roll down the hill and vice versa.


Surface Chart for 2 pm (18 UTC) Today. Note the Seven Relatively Close Isobars (Black Lines) on the Left (Western Caribbean) Compared with the Four Widely Spaced one on the Right (Eastern Caribbean). The Pressure Gradient and Winds are Much Higher across the West than the East.

Note, unlike the blog from yesterday that spoke about swell waves, this blog is focusing on wind waves. What is the difference? Swells are waves generated by distant winds and are of danger primarily to users of the near shore, beaches and coastlines. On the other hand, wind waves are locally generated and are mainly of danger to mariners using off shore waters.

The strong winds and hazardous seas will subside to relatively safe levels by late Friday. Keep following my blog and other media – TwitterFacebook and Instagram for more on this event and all things weather and climate.





A Major Swell Event to Impact the Caribbean This Week

21 01 2019

A major swell event is forecast to impact much of the Caribbean this week. Swells are likely to exceed 2.5 metres (8 ft) and occasionally exceeding 3 metres (10 ft), coming out of the north. These swells will result in dangerous surfs for beachgoers; hence, advisories and or warnings will be required.

Spacial Distribution of Swells - Thu 22 Jan 2019

Spacial Distribution of Swells – Thu 24 Jan 2019. Grapic Courtesy windy.com

The swell event will be generated by gale-force/storm-force winds, from a powerful low-pressure system, making its way across the northern North Atlantic. This is the same system that dumped an obscene amount of snow – over 660 mm (26 in) across parts the United States.  Obviously, none of this weather will reach the Caribbean but the sea swells will.

The swells in and of themselves are not the real concern. The greater concern is the large breaking swells or high surfs that these swells will caused when they reach the shorelines across the region. Such long period swells can result in surfs as high as twice their heights i.e. up to 6 metres (20 ft).

High Surf - Fort James, Antigua

High Surf – Fort James, Antigua

The eventual height of the surfs is largely dependent on the bathymetry (shape and depth) of the near shore coastal areas they interact with. Generally, the shallower the near shore areas, the higher the surfs. The greatest impact will be on the north-facing beaches and coastlines.

The event has started across the Bahamas and will reach the western Caribbean by tomorrow – Tuesday. It will then spread to the Eastern Caribbean Wednesday, including Antigua and Barbuda, and the southern Caribbean on Thursday. Moderate swells and associated high surfs are also forecast to reach the coastline of northeast South America, including the Guyanas on Friday.

These high surfs will have the potential impact of injuries or loss of life, beach closures and financial losses. Impacts could also include:

  • disruption to potable water from desalination;
  • salt water intrusion;
  • flooding of low-lying coastal roads;
  • beach erosion;
  • disruptions to near shore marine recreation and businesses;
  • damage to coral reefs and
  • disruptions of marine transportation.

These swells and surfs could result in strong rip currents that can carry even the strongest swimmers out to sea. Rip currents are powerful channels of water flowing quickly away from shore, which occur most often at low spots or breaks in the sandbar and near structures such as groins, jetties and piers.

If caught in a rip current, relax and float. Don`t swim against the current. If able, swim in a direction following the shoreline. If unable to escape, face the shore and call or wave for help.

There is also concern for those who visit non-beach coastal areas. High surfs can knock spectators off exposed rocks and jetties. Those who rock fish need to pay attention and not expose themselves to this hazard. Breaking waves may occasionally impact harbours making navigating the harbour channel dangerous.

With this event happening near a full supermoon, high tides will be higher than usual; hence, coastal flooding and erosion are more likely than usual. Coastal flooding from the sea is largely depended on high tides, onshore wind and swell actions.

The potential impacts listed above are just that – potential/possible impacts. I am not saying that they will all definitely happen, but conditions could result in such and past similar swell events have caused such.

If an high advisory is issued for an area – be extremely cautious; bathe only where lifeguards are present. If a high surf warning is issued – do not enter the water. Relatively safe conditions are likely on the opposite or southern sides of the islands.

Swells and associated surfs will peak across the Bahamas on Wednesday; the Eastern Caribbean on Thursday; the southern Caribbean Friday and northeast South America on Saturday.

In addition, to concerns for those using the beaches and coastlines, there are concerns for mariners of the northern islands, as expected strong winds will, among other things, cause hazardous seas. For more, see my blog – Strong Winds and Hazardous Seas to Impact Parts of the Caribbean, coming out tomorrow.





Wetter Than Normal November Eases Drought to Slight

31 12 2018

Dale C. S. Destin |

DroughtMeterNovember’s rainfall was higher than usual – 135% of the average for the month. The total of 204 mm (8.03 in) makes this November the 21 wettest on record. The very welcome rainfall has ease the meteorological drought to slight levels and have also eased or eliminated other droughts.

Over 95% of the rainfall for November fell during the first 15 days of the month, making it the second wettest such period on record. The rainfall was caused by a cold front and a series of troughs.

The last three-month period – September to November, upon which the assessment of the current intensity of the drought is based, was slight dry. Notwithstanding a wetter than normal November, the last three months, as a time interval, had below normal rainfall with 370.6 mm (14.59 in) recorded. This is the lowest since 2015 and the second lowest since 2009.

RainfallAccuForPast24Months

Rainfall for the past 24 months for varying time intervals compared to the normal/average and records

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity is slight. Recall that the overall description of the drought is based on the worst intensity achieve during its lifetime; however, over time, the intensity will fluctuate. Last month the intensity was at serious levels.

Potworks Dam, with a billion-gallon capacity, has moved from near totally dry to being one-third full, two-third empty – depending on your perspective. The water levels have gone above extraction height and I am advised that the same is true for the other smaller catchments.

Potworks Dams Nov13_2018_KarenCarbin

Potworks Dam – Nov 13, 2018. Complements Karen Corbin of the Humane Society

Potable water has become more readily available and water rationing has apparently cease, for now. This is indicative of huge dent November’s rainfall made on the droughts.

The fourteen-month period – October 2017 to November 2018, the duration of the drought thus far, is deemed severely dry. The total for the last 14 months of 977.6 mm (38.49 in) is the second lowest since 2001 – only the similar period October 2014 to November 2015 was drier. October of one year to November of the next normally gets 1514.6 mm (59.63 in), which means that there is a large rainfall deficit of around 35% – more than one-third of the usual rain did not fall.

Based on the last set of rainfall forecasts from regional and especially international sources, the news is discouraging with respect to rainfall. Overall, below normal rainfall is most likely for the next six months – January to June 2019, with relatively high confidence that the period January to March 2019 will be drier than normal – possibly well below normal. Thus, there is every reason to believe that the droughts will continue and likely reintensify. The chance of the droughts ending is, at most 30% or low.

MultimodelEnsembleRainfall_JFM_2019

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Jan-Mar 2019, based on 12 global model

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. At current, the drought is in its 15th month; the longest such drought on record lasted 38 months – Jul 2013 to August 2016.

I now expected 2018 to be among the top 10 direst years on record with the island-average total less than 900 mm or less than 35 inches. We normally get 1206.5 mm or 47.5 inches.

AccumulationJan_Dec2018

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All the best for 2019!





Steep Pressure Gradient to Cause Hazardous Conditions Across the Region

27 12 2018

Dale C. S. Destin|

Strong and gusty winds are forecast to move across most of the Caribbean this weekend – Friday through Sunday. These winds will make for hazardous conditions onshore and especially offshore. Some activities on land will become dangerous and marine conditions will be very hazardous for small craft operators.

The high winds and seas may be reminiscent of the passage of a weak tropical storm, but they won’t be due to any such system. The elevated winds will be the result of a very steep pressure gradient, due to the strength and location of the centre of a high-pressure system. The pressure gradient – the horizontal change of pressure, will be around 25% higher than normal.

Very hazardous seas in excess of 2.5 metres and rising to 3.5 metres (9 to 12 feet) will take place Friday through Sunday across the northeast Caribbean. Winds and seas will start building on Thursday – peaking on Saturday. Seas will occasionally reach 4.5 metres (15 feet).

These hazardous conditions will peak about a day earlier across the western Caribbean (including the Bahamas) and a day later across the southern Caribbean.

The winds will range between 34 and 45 km/h (21 and 32 mph) across the northeast Caribbean Friday through Sunday. Gusts to gale-force i.e. 64 km/h (40 mph) are expected. These kinds of winds very unusual for the region outside of being associated with a tropical cyclone (hurricane, tropical storm or tropical depression). The wind will generally blow from the east.

Possible impacts of the strong winds and hazardous seas include:

  • injuries or loss of life;
  • damage or loss of boats and fishing equipment;
  • disruptions to marine recreation and businesses;
  • disruptions to air and especially sea transportation;
  • disruptions to outdoor sporting activities;
  • disruptions of sea search and rescue;
  • scarcity of sea food;
  • vehicular accidents and
  • economic losses.

The worst affected area is likely to be the northern Caribbean – including the Leeward Islands and areas further west. Marine warnings are expected to be issued by most islands. Winds will be strongest over open waters, elevated terrains and windward coastal areas – eastern coastal areas.

Small craft operators and even some not so small crafts operators should stay in or very near port this weekend. Work at high and exposed evaluations should be avoided. Some outdoor activities may need to be postponed or adjusted for the conditions. Secure or take indoors light and loose objects – patio furniture, trash can etc..

Be very caution if you need to drive a high-profile vehicle, as strong winds could make for difficult, if not dangerous, driving of such automobile.

This event is not related to a tropical cyclone; nonetheless, some measures need to be put in place to mitigate the potential impacts – especially those related to the marine environment.

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The Fourth Longest Sub-Twenty Cold Spell for Antigua and Barbuda

23 01 2017

Dale C. S. Destin |

Last night’s cold weather makes the current sub-twenty °C (sub 70 °F) cold spell the fourth longest on record at the Airport and most of the rest of Antigua and Barbuda. It tied with February and December of 1973.

With a mean minimum temperature of 18.6 °C (65.5 °F), it is also the second coldest sub-twenty cold spell for the country, on record, lasting more than three consecutive nights. The mean minimum temperature for the past four nights ranged between 11 and 22 °C (71.6 °F) with the vast majority of places experiencing sub-twenty temperatures.

jan2017coldspelltemps

The last time the Airport had a temperature below 18 C was in 2000 – 16 years ago.

We are also looking at the coldest four-night period for January since 1980 – over 35 years ago, and since 2000 for all other months, at least, at the Airport.

Of the eight times we have seen this spell lasting more than three days, it has gone for four days twice and five days thrice, based on data for the Airport.

The record five-day sub-twenty cold spell is shared by March 1997, January 1984 and March 1972. The coldest one is March 1972 with a mean minimum temperature of 18.5 °C (65.3 °F).

So far for January, the mean minimum temperature at the Airport is now 21.9 °C (71.4 °F) – below normal. The mean daily temperature is well below normal with a value of 24.6 °C (76.3 °F).

There is now about a 50/50 chance the record will be tied tonight, as conditions could favour sub-twenty temperatures once again. If it were to happen, this cold spell would likely become the longest as the chances of sub-twenty temperatures are high for Tuesday and Wednesday nights. Usual January temperatures are expected after Wednesday.

The statements above are truest for the Airport and surrounding areas; however, from a qualitative assessment, it is applicable to the rest of the country.

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Potential Flooding Rainfall to End the Hurricane Season

28 11 2016

Dale C. S. Destin |

Satellite Image - Past 6 hrs Ending 11:45 UTC or 7:45 Local Time

Satellite Image – Past 6 hrs Ending 11:45 UTC or 7:45 Local Time

A surface low pressure system is expected to form near the northeast Caribbean and cause potential flooding rainfall across much of the Eastern Caribbean through Tuesday. Antigua and Barbuda is expected to see peak totals today – Monday.

The system could cause 25 to 100 mm (1-4 in) of rainfall, with locally higher amounts, from the Dominican Republic to Trinidad and Tobago. The epicentre of the rainfall is likely to be just south of Antigua or across the northern Windward Islands where the total could max-out above 100 mm (above 4 in).

North American  Mesoscale Forecast System (Model) Rainfall Accumulations - Nov 27-29, 2016

North American Mesoscale (NAM Model) Forecast System Rainfall Accumulations – Nov 27-29, 2016.

 

Globale Forecast System (GFS) Rainfall Accumulations for the Period Nov 27-29, 2016

Global Forecast System (GFS Model) Rainfall Accumulations for the Period Nov 27-29, 2016

With this type of rainfall, minor flooding is expected and moderate or worse flooding is possible. Hence, flash flood watches and warning may be required for a number of other areas over the next 12 to 36 hours.

This may be a fitting end to a very wet start to November. The month had a near record wet start across the Eastern Caribbean. In Antigua, some areas received upward 200 mm (8 in) during the first 10 days of the month. At the V. C. Bird International Airport, the rainfall stood at 143.5 mm (5.7 in) by November 10 – the third most on record dating back to 1928.

Rainfall Anomalies

Rainfall Anomalies for the Period Nov 1-10, 2016

With this type of rainfall, minor flooding is expected and moderate or worse flooding is possible. Hence, flash flood watches and warning may be required for a number of other areas over the next 12 to 36 hours.

This may be a fitting end to a very wet start to November. The month had a near record wet start across the Eastern Caribbean. In Antigua, some areas received upward 200 mm (8 in) during the first 10 days of the month. At the V. C. Bird International Airport, the rainfall stood at 143.5 mm (5.7 in) by November 10 – the third most on record dating back to 1928.

Recall also, that there were deadly floods and landslides across portions of St. Vincent during the early parts of the month.

The forecast rainfall for Monday is not a foregone conclusion but it is quite possible. If it were to materialized, this November would be one of the wettest on record for much of the Eastern Caribbean. In Antigua, it would be the wettest since Hurricane Lenny’s deluge of 1999 and be among the top 10 wettest Novembers of all time.

After the low, very cool northerly winds are expected to blow across the region. These will likely cause our coolest weather for the season and since February. Night-time temperatures could fall to below 19 °C (66 °F) Monday, Tuesday and Wednesday nights.

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Hold on to Your Hats and Skirts!

31 12 2014

Dale C. S. Destin |

Forecast Wind Speeds - Sun Jan 4, 2015

Forecast Wind Speed – Sun Jan 4, 2015

Hold on to your hats and skirts and batten down the hatches. Strong winds and very rough seas to kick off the new year across Antigua and much of the Caribbean.

The winds will become stronger with peak sustained speed near 25 mph (22 knots) over the weekend across Antigua and Barbuda. The winds will also be very gusty with gusts as high as 37 mph (32 knots) possible, just 2 mph short of storm force.

Forecast Wind Gust - Sun Jan 4, 2015

Forecast Wind Gust – Sun Jan 4, 2015

The strong winds will stirrup very rough seas in our area. Seas could peak as high as 3.6 metres (12 ft) Sunday and continue above 2.4 metres (8 ft) until, at least, the middle of next week. By next Thursday there could be a transition from wind waves to swell waves from a frontal low pressure system.

Forecast Wave Height - Sun Jan 4, 2015

Forecast Wave Height – Sun Jan 4, 2015

The strong winds are in response to the steepening of the pressure gradient across the area. You may recall that winds are the horizontal movement of air. They only occur due to the spatial deferential in atmospheric pressure. The change in pressure across a particular area is called the pressure gradient. The steeper the gradient or greater the pressure difference between two points, the stronger the winds and vice versa.

Warnings are already in effect for hazardous seas that are bound to get much worse. Mariners should consider staying near shore until winds and seas subside, perhaps late next week.

The strong winds could make certain activities uncomfortable, if not dangerous. For example, working at elevation could be dangerous and should be curtailed until the winds return to normal speeds.

The worst conditions will be seen in the western Caribbean Seas, juts north of Columbia. The winds are expected to peak near 44 mph (38 knots) with gusts near 54 mph (47 knots); this is tropical storm strength and under tropical cyclone criteria would require a tropical storm warning. Wave heights will approach 6 metres (20 ft).

This area of storm force winds is pushing large waves outward which will cause most of the Caribbean Sea to be rough for the next several days. Mariners should avoid travelling not only the Atlantic waters of the Caribbean but also the Caribbean Sea, especially the western Caribbean Sea south of Jamaica.

Feel free to share with us your experiences of this strong wind and very rough seas event and follow us on wordpress: 268weather.wordpress.com twitter: @anumetservice facebook: /anumetservice tumblr: anumetservice.tumblr.com to keep current with weather and climate info.

Happy New Year!








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