Wet Weekend for the Northeast Caribbean

28 04 2022

Dale C. S. Destin |

A trough system is poised to cause wet weather across the northeast Caribbean, including Antigua and Barbuda. Several of the more reliable weather models are forecasting the potential (10 percent chance) for rainfall totals exceeding 25 mm (over 1 in) to fall over the period Friday to Sunday of this weekend.

The potential total for over 25 mm in 72 hours is not in and of itself a high figure. However, relative to April and the fact that we are in a severe drought makes this worth “writing home about”.

Whereas all models consulted are forecasting rainfall for the weekend, the forecast totals differ, as can be expected. At the lower end of the potential rainfall scale some are projecting a 10 percent chance of over 25 mm (over an inch), while others are suggesting potentially higher totals, a 10 percent chance of over 75 mm (3 in) for the weekend.

GFS 24hr precipitation total exceedance forecast probabilities showing all areas with at least a 10 percent chance of getting over 50 mm (2 in) of rainfall from 2 am Saturday, 30 April to 2 am Sunday, 1 May 2022

The wet weather is expected from Dominica to Hispaniola. The highest totals are likely across Puerto Rico and the Virgin Islands Saturday/Sunday. Most of the rainfall for Antigua and the rest of the Leeward Islands is likely Friday/Saturday and for Hispaniola Sunday/Monday.

If the models prove right, and the upper end of the rainfall potential materialises, some places across the northeast Caribbean could see the average total for April falling in one weekend, if not one day. The possible rainfall total for the area is 25 to 100 mm (1 to 4 in). With this kind of rainfall possible, depending on the intensity and duration, flash flooding and associated impacts are of concern.

Deterministic rainfall accumulation forecast by the GFS model from Thursday, 28 April to Sunday, 1 May 2022

The rainfall of this weekend could, at least, put a dent or further dent in the droughts across the area, particularly the Virgin Islands and Puerto Rico. It will certainly have a big impact on domestic catchments, temporarily easing the stress and demand on water resources authorities.

There is no doubt that these showers will be welcome by all; however, they could prove disruptive to weekend plans leading up to Labour Day Monday celebrations. Good news though: The weather should just about be back to normal by Monday.

The system has already caused wet weather across the southern Caribbean with some areas receiving over 75 mm (3 in). The trough also prompted flash flood warnings for some islands.

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Relatively Very Wet Weekend Possible for Parts of the Northeast Caribbean

4 02 2022

Dale C. S. Destin |

A cold front looks poised to cause a relatively very wet weekend across much of the northeast Caribbean, including Antigua and Barbuda. Several reliable models are forecasting possible rainfall totals of 25 to 76 mm (1 to 2 in) to fall over the period Friday to Sunday.

Proxy visible satellite image

The potential total of 76 mm in 48 to 72 hours is not in and of itself a high figure. However, relative to February, this is a lot of water. The average rainfall for the second month of the year is 50.0 mm (1.97 in). This means we could welcome more than the average for the month, in a few days.

After this weekend, this February could be the wettest since 2004, ranking among the top 10, on record. Only seven Februarys, on record dating back to 1928, had more than 76 mm (3 in) of rainfall.

GFS model indicating 30-40% chance of more than 25 mm in 24 hours ending 8 am (12 UTC) Saturday, 5 Feb, 2022

If the models prove right, this weekend would easily be the wettest in, at least, 16 weeks and the wettest month in four months. Some parts of the country could see a record wet first week of February. The record for February 1-7, at the Airport, is 54.8 mm (2.16 in), which occurred in 2002. We could also see the 24-hour rainfall accumulation, across some parts of the island, exceed 25.4 mm or one inch, for the first time since 2004 and the fourth time on record.

Notwithstanding the potential for a relatively very wet weekend, this will have minimal impact on the droughts. It will likely have a big impact on domestic catchments but virtually no impact on the island’s catchments.

There is no doubt that these showers would be welcome by all; however, they could prove very disruptive to the ongoing ICC Under-19 Cricket World Cup, which climaxes this weekend, with the final and third-place position. It will likely also be disruptive to other outdoor events.

The system has already caused wet weather across Hispaniola and Puerto Rico with isolated totals of up to 203 mm (8 in). If this amount were to reach us, it would cause absolutely wet conditions and place a dent in the drought, but it is very unlikely that we will get this lucky.

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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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Potentially Drought-Busting Rainfall This Week

17 04 2016

Dale C. S. Destin |

A trough system could potentially cause drought-busting rainfall across Antigua and the rest of northeast Caribbean during this week. The system could dump up to 150 mm (6.0 in) of rain on the Leeward Islands and the Virgin Islands over the next six days, starting  tonight – Sunday night.

GFS forecast rainfall total for the period 2 pm, April 16 to 2 pm, April 23, 2016

GFS forecast rainfall total for the period 2 pm, April 15 to 2 pm, April 22, 2016

We could get drought-busting rainfall i.e. sufficient rainfall to bring a welcome end to the meteorological and agricultural droughts taking place across Antigua and nearby islands. However, it is unclear as to whether it will be enough to replenish surface catchments and aquifers to end the more serious socioeconomic droughts, which are costing the islands dearly. Nevertheless, the rainfall is likely to put a big dent in this drought also.

Given the potential amount of rainfall that could occur, at least moderate flooding is possible of low-lying and flood-prone areas across the northeast Caribbean, including Antigua and Barbuda. Thus, the requisite watches and warnings may be required for portions of this week.

GFS probability forecast of total rainfall for April 17-23 exceeding 75 mm (3 in)

GFS probability forecast of total rainfall for April 15-22 exceeding 75 mm (3 in)

GFS probability forecast of total rainfall for April 17-23 exceeding 150 mm (6 in)

GFS probability forecast of total rainfall for April 15-22 exceeding 150 mm (6 in)

A number of weather models, including two of the best – the Integrated Forecast System (IFS) and the Global Forecasting System (GFS), are showing very high probabilities of this week being very wet, especially relative to April. However, it is not a 100% certain. Further, the eventual rainfall total is quite uncertain.

Most for the precipitation is likely to be in the form of rain from layer-type clouds as opposed to the showers from convective-type clouds. Notwithstanding, thunderstorms are possible every day from Monday to Friday. The sun could also be hidden by thick clouds for most of the week.

The normal rainfall for April is 85.6 mm (3.37 in). On record dating back to 1928, April 1981 is the wettest with 245.4 mm (9.66 in), and the driest is April 1944 with 5.8 mm (0.23 in). At the V. C. Bird International Airport, the normal rainfall for April 17-22 is 12.7 mm (0.50 in). The wettest was 1992 with 112.0 mm (4.41 in) and the driest of 0.0 mm occurred on at least six occasions since 1961.

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A Break in the Warm Surge for the Western Caribbean

30 04 2015

Dale C. S. Destin |

A cold front is set to dowse the western Caribbean and the Bahamas with heavy showers over the next several days.

2 AM SURFACE PRESSURE ANALYSIS FOR THU APR 30 2015

                               2 AM SURFACE PRESSURE ANALYSIS FOR THU APR 30 2015                               CREDIT NOAA

10:45 AM SATELLITE PICTURE

10:45 AM SATELLITE PICTURE

These showers will be very heavy at times and are expected to will break the warm, dry spell for that part of the region; however, the rest of the area will continue to see scorching weather.

The high pressure ridge, which is the main cause of the parched weather across the region, will block the progress of the front causing it to linger for much longer than normal across the Western Caribbean.  Precipitation from this system could continue well into next weekend, with few breaks.

RAINFALL FORECAST FOR APR 30 TO MAY 7, 2015

ONE WEEK RAINFALL FORECAST: APR 30 TO MAY 6, 2015

Possible rainfall totals over the next seven days across the Bahamas and Cuba are 100-200 mm (4-8 in). This could cause like threatening flash floods and mudslides in some areas. Much lower totals are possible across the Cayman Islands, Jamaica and Hispaniola.

Notwithstanding the potential for flooding, this will be much welcome rainfall as many places across the Bahamas and Cuba are experiencing rainfall deficits. And like the rest of the Caribbean, El Nino is likely to cause significant rainfall deficits for upcoming months.

We will be following this weather as it unfolds.








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