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: anumetservice.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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