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.

Follow us for all you need to know about this cold spell and all things weather and climate. We can be followed on twitterfacebookinstagramtumblrflickrgoogle+, and youtube.





A Hat-trick of Sub-Twenty Temperatures for most of Antigua and Barbuda

22 01 2017

Dale C. S. Destin |

Last night’s cold weather makes it a hat-trick of sub-twenty temperatures for most of Antigua and Barbuda. This is a fairly rare feat for the country. It has only happened seven other times during January, based on historical data for the Airport. The last time it happened in January was back in 1996 – 20 years ago. The last time it happened for any month was in March 2000.jan2017temperatureWhereas the last hat-trick of sub-twenty temperatures occurred last in January 1996, the coolest such period last took place in 1992. It is also the coolest such period, for all months, last occurred in March 2000. This and the rest of what is said here is an update on the previous blog.

The mean minimum temperature for the past three nights, at the Airport, was 18.5 °C (65.3 °F). This is the eighth coldest for three or more days in a row with sub-twenty temperatures at the Airport. Further, it is the 12 coldest for any three-day sub-twenty spell (overlapping and otherwise).

When we consider such a three-peat of sub-twenty temperatures for all months dating back to 1971, it has only happened 27 previous times.

So far for January, the mean minimum temperature at the Airport of 22.0 °C (72 °F) is below normal. However, up to three days ago, it was bordering on above normal – meaning we were having relatively warm nights for this time of the year. The mean daily temperature is well below normal with a value of 24.7 °C (76.5 °F).

As cold as it has been, it certainly has NOT nearly been cold enough to freeze water. Thus, that picture being circulated suggesting that the cold weather caused a small body of water to freeze in Free Town is a HOAX. For this to happen, we would need to have sub-zero temperatures persisting for days, which will NEVER happen.

There have only being five occasions when sub-twenty degree nights have occurred for more than three consecutive nights. Tonight is likely to be the sixth time this has happened. So far, today has been coldest of the past three days.

After tonight, the weather will warmup to usual temperatures for this time of the year. Then the cold weather will more likely than not return on Wednesday and continue on Thursday. Thereafter, the usual temperatures for this time of the year is expected to prevail for the rest of the month.

Although we are unable to say definitively how cold the country or specific areas have been due scarcity of historical temperature data, it is likely the coldest since 1996. This is based on fact that temperatures across a small homogeneous area like Antigua and Barbuda are highly correlated. And since it is the coldest for the Airport since 1992, it should be likewise for the rest of the islands.

From a quantitative standpoint, 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.

Follow us for all you need to know about this mini-cold spell we are experiencing. We can be followed on twitterfacebookinstagramtumblrflickrgoogle+, and youtube for education and information on all things weather and climate.





How Cold was Antigua and Barbuda Last Night?

20 01 2017

Dale C. S. Destin |

By Caribbean standards, the last two nights were very cold for Antigua and Barbuda. One of the coldest spots on the islands was Free Town, which had a minimum temperature of 13.9 °C (57.0 °F) night before last and 11.6 °C (52.9 °F) last night.

picture2jan212017picturejan202017The 11.6 °C  is now the lowest temperature ever measured by the Met Office. It eclipsed the previous short-lived record of 13.9 °C. However, it is unlikely to be the lowest temperature ever experienced in Free Town or by the country. The lowest ever measured is not the same as the lowest on record or in history.

Unfortunately, apart from the Airport, there were NO reliable temperature sensors elsewhere across the country until a few years ago. There exists very little historical data for Free Town, as the station was only installed last January. The same is true for most of the other stations listed above. Thus, regrettably, I am unable to say definitively just how cold it was in Free Town and most of the other locations.

The only site for which historical data exist is the Airport. The minimum temperature measured at the Airport last night was 18.4 °C (65.1 °F); this is well above the record of 16.1 °C (61.0 °F), measured back in December 1974 and January 1976.

Making some reasonable assumptions and using the Airport’s temperature from last night as a “barometer” for the rest of the country, last night was the coldest January night since 1996 and the 12th coldest dating back to, at least, 1971.

Last night, the minimum temperature range for Antigua and Barbuda was 11.0 to 21.0 °C (52 to 69.8 °F) . The previous night it was 13.0 to 22.0 °C (55.4 to 72 °F). It is possible that a few areas had temperatures slightly below or above this range.

The cold weather last night was due to the time of the year, light winds, mostly clear skies and low moisture levels. Last night was colder than Thursday night mainly because moisture levels were lower. These conditions will continue for the next 24 hours; hence, tonight is expected to be similarly cold. Thereafter, the winds will increase and so will the temperature.

With the few cold nights, some have advanced the notion that we are having a colder than usual January. However, this is not borne out by the data at the Airport, thus far. The mean minimum temperature up to two days ago, at the Airport, for the month was 22.6 °C (72.7 °F), 0.2 °C above the average of 22.4 °C  (72.3 °F).

The cold weather was also experienced across most of the rest of the northeast Caribbean for the second night also. Le Raizet, Guadeloupe had a minimum of 17.6 °C (63.7 °F) night before last and 16.8 °C (62.2 °F) last night, meanwhile Clayton J. Lloyd International Airport in Anguilla had 19.4 °C (66.9 °F) and 20.2 °C (68.4 °F) respectively.

Will it be colder tonight, with some places having sub 10 °C (sub 50 °F)? Follow us via our social media platform:  twitter,  facebook,  instagramtumblrflickrgoogle+, and youtube and stay informed. We would also be happy to hear from you regarding how cold you felt and your experience with the weather generally.





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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The Status of Cold Temperature Extremes for Antigua

10 02 2016

Dale C. S. Destin |

Last week we had an extremely cold night (relative to our climate) and a few cool nights which led some persons to ask with “tongue-in-cheek” if we going to have snow. Are cold extremes becoming more or less frequent? What can we expect as our climate changes?

When I was growing up, I remember it was very common place to see our breaths (as mist) in the mornings, due to extremely low temperatures, at this time of the year. It was fun for us as we would pretend to be blowing smoke from our mouths and also blow mist onto the mirrors and then draw or write on them.

The fact is, such low temperature extremes, are decreasing fairly rapidly. So, the cold nights we had last week, are becoming more a thing of the past or a once in a “blue moon” event. 2015 had a record low number of extremely cold nights – 6 or 2% of the number of nights for the year; the next fewest is 2002 with 14 or 4%.

ExtremelyColdNights

Data at the V. C. Bird International Airport (VCBIA), where the Met Office is located, show a significant decline in extremely cold nights, while extremely warn nights are on the increase but not yet considered to be rising significantly.

ExtremelyWarmNights

Extremely cold nights here mean nights with the minimum temperature in the bottom 10-percentile based on the climate period 1971-2000. Extremely warm nights are those with minimum temperature in the top 10-percentile.

This year in particular, nighttime lows are expected to be much higher than normal due mainly to the ongoing El Nino or warmer than usual sea surface temperatures (SSTs) across the equatorial Pacific.

El Nino causes higher than normal surface pressure across the equatorial Atlantic, which acts to weaken the trade winds. Weakened trade winds then translate into warmer than normal SSTs and the air in contact with it; hence the warmer than normal nights.

As our climate changes, cold extremes will continue to decrease and warm extremes are expected to increase. Thus, the drop in temperature to cold extremes will become fewer and the spikes to warm extremes will become more and more common place

Weather extremes are generally undesirable. Cold extremes cost us nothing as it is fairly easy to warm ourselves. On the other hand, warm extremes have negative implications for our health, economy and ecosystem.

So far for the year, there have been fewer than normal extremely cold nights at the VCBIA – one, and more than normal warm nights – nine or 23% of nights to date for 2016.

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January 2016 Newsletter

27 01 2016

Dale C. S. Destin |

Our January 2016 newsletter is now available. In it you will find the latest on our weather and climate and forecasts for the next six months.

The notable events of the past three months include the fact that the drought has re-intensified, October to December has been the 9th driest on record and December was among the warmest.

Impacts from the drought include empty surface catchments, households without pipe-borne water for weeks and insufficient water to properly support agriculture and livestock. Over 90% of potable water comes from the sea via the very expensive means of desalination.

For the period January-March, below to near  normal rainfall is anticipated; thus, the continuation of drought and related challenges. However, above to near normal rainfall is forecast for April-June; hence, the drought is forecast to ease or come to an end.

For more, please see our newsletter here: ABMS Climate Section (CliSec) Newsletter





Record Heat for October 2015

30 11 2015

Dale C. S. Destin |

A number of temperature records were broken or equalled during October across much of Antigua and Barbuda. The first day of October, we measured at the at the Met Office, located V. C. Bird International Airport (VCBIA), the highest temperature on record for the month – 34.0 °C (93.2 °F), and the fifth highest for all months dating back to 1971.

heatwave

We also recorded the second highest temperature for October – 33.9 °C (93.0 °F), and the sixth highest ever recorded at VCBIA.

These extreme temperatures were a part of a heatwave which began on September 30 and continued through October 7. During this time, the daily maximum temperatures were at record high or among the 10 percent highest temperatures for the given period.

The eventual mean daily maximum temperature (the mean of highest temperature for each day) was 31.2 °C (88.2 °F) or 0.6 °C (1.1 °F) warmer than normal. It tied with five other Octobers for the highest for the month.

Meanwhile, relative to October, minimum temperatures were quite oppressive. Many nights saw record or near record high minimum temperatures. There was a record number of “warm nights” (minimum temperature among the top 10 percent highest) – 12, shattering the previous record of 8 the month.

The mean minimum temperature (the mean of lowest temperature for each day) tied with that of October 2001 for the highest on record for the month.

The mean minimum temperature – 25.5 °C (77.9 °F) was 1.1 °C (2.0 °F) higher than normal. The excess (anomaly) above the usual mean minimum temperature for October was around twice that of the excess above the usual mean maximum temperature. Thus, the cooling that normally occurs at night did not take place, allowing for very little needed respite from the heat.

The overall, the mean daily temperature was also near record high – 28.1 °C (82.6 °F) or 0.6 °C (1.1 °F) higher than normal. It tied with 2001 for the third highest for October.

Sea surface temperatures (SSTs) around Antigua and Barbuda were also at record high levels for the month – 29.6 °C (85.3 °F) or 0.9 °C (1.6 °F) warmer than usual and tied with 2013 for the warmest SSTs for our area for October, dating back to 1854.

Oct2015_SSTs

October also saw record high SSTs across the tropical North Atlantic and Caribbean Sea – 28.6 °C (83.5 °F) or 0.7 °C (1.3 °F) higher than normal.

On a global scale, it was the warmest October on record with the global mean surface temperature was near 15.0 °C (59.0 °F) or 1.0 °C (1.8 °F) higher than usual.

Much of the warmth across Antigua and Barbuda and the rest of the region were due to the persistent weak nature of the Atlantic high pressure system, mainly during September, which translated into light winds that allowed for SSTs to soar.

We will let you know if this warm trend continued through November, shortly.








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