The Sixth Driest Start to September

20 09 2014

Dale C. S. Destin |

After encouraging rainfall for August, September has been quite disappointing, thus far. The first half of September has been severely dry across much of Antigua according to preliminary statistics at the Antigua and Barbuda Met Service.

Figures up to September 15 show there has been 16.3 mm of rain at the Met Office located at the V. C. Bird International Airport. This is only 12.4% of the September average of 131.6 mm. We would expect about 57% or 74.6 mm of the month’s rainfall to have fallen by this point.

 

SixDriestFirstHalfOfSeptThis makes this first half of September the sixth driest at the Airport based on available records dating back to 1960. Apart from the first half of September of 2012 which yielded just 2.3 mm, no other such first half has been drier since 1990.

The low rainfall figures appear to be due mainly to the pressure across the North Atlantic being higher than normal or a positive North Atlantic Oscillation. This translated into a persistently stable and relatively dry atmosphere, and hence minimal rainfall.

While these figures are interesting, they don’t tell us where the month will end up overall. A few days of wet weather, which we are hoping for, could drastically alter the statistics. So we’ll have to wait for the full-month figures before making any judgements.

While there is no dramatic rainfall expected, several weather models are indicating healthy probabilities for showers over the next several days, particularly Sunday-Monday when the next tropical waves is expected in the area. However, models also are forecasting the NAO to remain positive. Thus, the total for the second half of the month could be similar to that of the first half.

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Record Breaking Rainfall

11 05 2012

by Dale C. S. Destin

This is the wettest start to May at the V. C. Bird International Airport, based on available record, which dates back to 1971. The rainfall for the first seven days of May, 2012 is now the most on record for all Mays with 121.9 mm or 4.80 inches; the previous highest was 63.4 mm or 2.50 inches recorded in 1990. The rainfall was caused by a persistent deep-layered trough system, which channelled a lot of moisture from South America into the area resulting in periods of rain, showers and thunderstorms. The heaviest rainfall occurred on Saturday, 5 May with 76.5 mm or 3.01 inches falling in a short period of time, about 3 hours. This resulted in minor to moderate flooding in some low-lying and flood prone areas. May 5 also had its highest total on record, and it tied with May 30, 1992 for the fourth wettest day for all Mays.

Our outlook for May calls for above normal rainfall and near normal temperature and wind. Given what has happened thus far, we could easily see this May becoming one of the top 10 wettest Mays on record. Does anyone want to guess/forecast what the final rainfall total for the month at the airport is going to be?  Here is a guide; the average and median totals for May 12 – 31 are 16.6 and 25.1 mm respectively; the max and min totals are 444.8 and 7.5 mm respectively (1981 – 2010). What is your guess/forecast total for the month? Tweet us at www.twitter.com/anumetservice or www.facebook.com/anumetservice.

Daily Rainfall Totals at the V. C. Bird International Airport – May 1 to May 7, 2012:

May 1    1.0 mm or 0.04 in

May 2    3.0 mm or 0.12 in

May 3    10.7 mm or 0.42 in

May 4    0.9 mm or 0.04 in

May 5    77.9 mm or 3.07 in

May 6    10.6 mm or 0.42 in

May 7    17.8 mm or 0.70 in








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