Our May Newsletter is now Available

19 05 2015

Dale C. S. Destin |

We’d like to present you with our May newsletter. In this newsletter, you’ll find highlights of recent weather and climate news. Additionally, there are outlooks for the upcoming six months. Links are also provided for further information. Please read and feel free to share you feedback.

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Follow us also on @anumetservice, facebook and tumblr for the latest on the current drought and other weather & climate news.

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Near Record Dryness for the First Half of May

17 05 2015

Dale C. S. Destin |

The first half of May 2015 is over and the Met Office, located at the V. C. Bird International Airport, Coolidge, Antigua, has measured only 1.7 mm (0.07 in) of rainfall. This represents the second driest such period on record. The only time May 1-15 was drier was back in 2001.

May 1-15 Rainfall at the V. C. Bird Int'l Airport

We are clearly not having a normal May or year but normally we would have received around 37.8 mm (1.49 in) by now. Instead, we have had near record dryness.

The rest of the country has not fared better. In fact, there are a few areas that are yet to see measurable rainfall for the month. Neighbouring islands are also experiencing similar rainfall deficits.

This severe dryness for the first half of May is very rare. On average, this happens once every 250 years, which translates to a 0.4% probability of May 1-15 being this dry.

The near record low rainfall seems largely connected with the anomalous cooling of the tropical North Atlantic which is associated with a positive North Atlantic Oscillation (NAO). Another significant driver of the dryness is the above normal flow of very dry, dusty air from the Sahara Desert to the region.

A dry start to the month does not always imply a dry month; however, of the six other times we have had 10 mm (0.40 in) or less for the first half of May, the eventual month’s total has never exceeded 56 mm (2.20 in). Only once such a dry start did not signal a dry month.

Overall, the second half of May has produced as little as 3.9 mm (0.15 in) and as much as 434.7 mm (17.1 in). Hoping to be wrong, but it would not be “tempting fate” to say that we absolutely will not get anywhere remotely close to 434.7 mm over the next two weeks.

Climatologically, the past 30 years show that rainfall on a whole for May is not changing. However, May 1-15 is trending positively (wet) while May 16-31 is trending negatively (dry). These trends are not considered significant, at the moment, but May 1-15 is not far away from being so.

The driest May on record at the Airport, dating back to 1928, is May 2001 with 7.6 mm (0.30 in). This record appears to be in jeopardy.

Follow us also on @anumetservice, facebook and tumblr for the latest on the current drought and other weather & climate news.





Early Start to the Atlantic Hurricane Season?

4 05 2015

Dale C. S. Destin |

Notwithstanding the forecast for a quiet Atlantic hurricane season this year, it looks like we will see an early start to the season.

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ECMWF Tropical Cyclone Strike Probability Forecast

ECMWF Tropical Cyclone Strike Probability Forecast

The U.S. National Hurricane Centre is presently indicating a low chance of tropical cyclone (depression, tropical storm or hurricane) formation in the next five days. However, one of the most reliable weather models, ECMWF, is indicating a high chance, up to 70% probability, of a tropical cyclone forming later this week, just north of the Bahamas.

If it forms, it looks likely that it will have an impact of the Carolinas and nearby southeast coastal areas of the United States. At most, they may have to deal with the effects of a strong tropical storm.

Antigua and Barbuda, has not been affected by a preseason storm in over 60 years and that streak is not expected to end this year. Our last preseason system was Hurricane Alice2 in January 1954, which actually formed in December 1953. Most of the rest of the Eastern Caribbean has never had a preseason storm and that is not about to change this year.

The initial disturbance is likely to develop from a cold front currently causing extremely wet weather across portions of the Cayman Islands, Cuba, the Bahamas and south Florida. Already, there has been massive flooding in Cuba causing three deaths and forcing tens of thousands from their homes.

TRMM_Rainfall

TRMM satellite has estimated up to a staggering 300 mm (12 inches) of rain has fallen across parts of Cuba and the rest of the affected area within the past seven days. Another 100 mm (4 inches) is possible over the next three days; hence, more flooding is expected.

It’s relatively rare but not unheard of for tropical storms to form in May. According to AOML, there have been 20 tropical storms in May over the period 1851-2014. This translates to one in every nine-ten years, on average. The last May storms were Alberto and Beryl in 2012.

Preseason tropical cyclones have no known omens for the Atlantic hurricane season. So, whether or not there is an early start, a quiet season is most likely this year, given the existing and expected prevailing atmospheric conditions.

Officially, the Atlantic hurricane season runs from June 1 to November 30.

We will continue to monitor this developing story.








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