Drier Than Normal May for Antigua, Droughts Reintensify

28 06 2018

Dale C. S. Destin |

The rainfall for May 2018 was below normal for Antigua. The total of 43.9 mm (1.73 in) was only 42% of what normally falls – 103.6 mm (4.08 in). Thus, there was a 58% deficit of rainfall for the month.

DroughtDial-Slight_to_ModerateThe last three-month period – March to May, upon which the assessment of the current intensity of the drought is based, had 135.1 mm (5.32 in), only 56% of the normal total of 240.8 mm (9.48 in). This puts the meteorological droughts current intensity at moderate, declining from slight.

With Potworks Dam totally dry and the vegetation of the Island struggling, there is little doubt that most other droughts are at moderate levels or worse. Happily, the full impacts of the droughts continue to be masked by the presence of the desalination plants.

The eight-month period – October 2017 to May 2018, the duration of the drought thus far, is deemed severely dry. This means that the total is in the bottom 5% of the historical data; such dryness is unusual – it happens, at most, once every 20 years, on average. The total for the period of 451.9 mm (17.79 in) is the lowest since 2001 and the fourth lowest on record dating back to 1928. The period normally gets 775.7 mm (30.54 in).

TemporalRainfall

Based on the last set of rainfall outlooks, the news is not good for rainfall. Overall, below normal rainfall is most likely for, at least, the next three months – July to September. Further, recent outlooks from global models indicate that the next six months will see below normal rainfall. Thus, there is every reason to believe that the droughts will continue and likely worsen.

The rainfall total for the year thus far – January to May, is well below normal. The 365.3 mm (14.38 in) is only 66% of what normally falls. Of the 91 years on record, only 17 have been drier to this point.

RainfallAccumulations_May2018

Even if the rainfall total turns out to be near average, it will not be enough, especially with respect to the hydrological drought, as the monthly evaporation rates will significantly exceed rainfall totals for most of the upcoming months. The chance of the droughts ending is around 20% or slight.

Recall that the current drought started in October 2017 with the intensity at serious levels. On average, serious meteorological droughts last for close to a year, but not continuously at serious intensity. We have just passed the eight-month mark. Will it go another four months? The answer still looks more like to be yes than no.

If you found this article informative, I would be very grateful if you would help it spread by emailing it to a friend, or sharing it on Twitter or Facebook.

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Windy Weather to Cause More Hazardous Seas and Economic Losses

8 01 2018

Dale C. S. Destin |

Hazardous seas being caused by frequently strong winds – gusting to near gale force at times, will continue to keep most mariners in or near port over the upcoming week – causing further significant economic losses for many.

Seas around Antigua and Barbuda have been rough for most of the year, so far, and are set to remain that way or even worsen over the next seven days, at least. As usual, this type of weather is very disruptive to marine activities and have a negative economic impact, particularly on fisherfolk, those alone the fisheries value-chain and those involve in offshore pleasure cruises and adventures.

Small craft warning remains in effect for hazardous seas around Antigua and Barbuda and will likely remain in place for the rest of the week. Hence, small craft operators, especially inexperienced ones, should avoid navigating in these conditions.

Warnings are also in effect for beach-goers as high surfs are affecting beaches, producing beach erosion and dangerous swimming conditions. Beach-goers should avoid the waters, especially those on the northern and eastern side of the islands. These high surfs are likely to subside to more manageable levels by Tuesday.

High surfs can also cause strong rip currents, which can carry even the strongest swimmers out to sea, and seawater splashing onto low-lying coastal roads, causing damage. Further, high surfs can also knock spectators off exposed rocks and jetties. Breaking waves may also occasionally impact harbours making navigating the harbour channel dangerous.

The wind speed will range between 14 and 22 knots (16 to 25 mph) and at times gusting to near 30 knots (35 mph). The winds will be strongest on Tuesday and Friday and will blow from near east for most of the week.

Wind speed – valid at 6 am, Tue, Jan 9, 2018

Seas will remain hazardous with steep waves ranging between 2 and 3 metres (7 and 10 ft), occasionally reaching near 4 metres (13 ft), mainly in open waters on the eastern or windward side of the islands.

Significant wave height (ft) – valid at 6 am, Tue, Jan 9, 2018

These strong winds not only cause hazardous seas but also cause certain onshore activities to be uncomfortable, if not dangerous. Hence, certain outdoor work will be hampered, if not halted, at times; thus, reducing productivity in other sectors.

The windy conditions and hazardous seas will also be experienced by all the islands of the Eastern Caribbean along with Hispaniola and the Bahamas, particularly the Atlantic coastal waters or the eastern and northern coastal waters.

The strong winds are not due to any storm system but rather because of steep pressure gradients across the area. Recall that winds blow due to pressure differences or pressure gradients, and the greater the gradients the stronger the winds and vice versa.

Also, the strength and position of the ever-present subtropical/Atlantic high-pressure system modulate the steepness of the pressure gradient. The closer and or stronger the subtropical high, the steeper the gradient, the stronger the winds and vice versa.

The subtropical high-pressure system will be stronger than normal for much of the next week; hence, the forecast continuation of strong winds, hazardous seas, disrupted marine activities and economic losses.

Although windy, the weather will be mostly dry with only occasional brief showers likely.

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Dangerous Surfs to Threaten Beachgoers in Antigua and Barbuda Easter Monday

17 04 2017

Dale C. S. Destin |

Those heading to the beaches in Antigua and Barbuda should be wary of the threat of strong rip currents Easter Monday through Wednesday.

Seas Forecast Apr 17, 2017

Beaches on the northern and eastern sides of the islands will be at greatest risk for stronger and more frequent rip currents through midweek, due to large swells. Seas are on the rise and will peak on Tuesday with a combination of wind waves and swells nearing 3.0 metres (10 ft) occasionally reaching 3.8 metres (13 ft).

A huge low pressure system near the centre of the North Atlantic is pushing large swells to the region. Meanwhile, the winds in the area are on the increase, which will cause a rise in the wind waves.

Low pressure systems

Rip currents are not new to our shores. They are always present in situations like this and are characterised by water flowing away from the shore. The strength of the current is usually proportional the height of the swells.

Vacationers and residents should take precautions while at the beach. It would be prudent to seek out only beaches under the watch of lifeguards, if possible, and heed all warnings issued. The west facing beasches should be least affected.

Should you ever get caught in a rip current, never attempt to swim directly back to shore as you will be swimming against the current. Instead, swim parallel to the beach to escape the current’s grip before swimming ashore.

Small craft should use caution and heed all advisories, as seas will also be rough.

Similar sea conditions are forecast for most of the rest of the Leeward Islands, the Virgin Islands, Puerto Rico, Hispaniola, the eastern parts of the Bahamas, the Winward Islands and Barbados. The swells will also eventually reach Trinidad and Tobago and the Guyanas late Tuesday.

It is also likely to be a somewhat wet Easter Monday as the same low pressure system mentioned above is pulling a lot of moisture across the islands. The range of the possible rainfall total is wide – 0 to 12 mm (0 to 0.48 in).

The increasing wind will peak late Easter Monday at around 16 knots (18 mph) over open waters and 13 knots (15 mph) over land. Frequent higher gusts will take place.

Seas will return to near normal levels on Thursday.





Storm-Force Wind Gusts and Hazardous Seas Are Returning to the Area

7 03 2017

Storm-force wind gusts and hazardous seas are returning to the area. The weather will be generally good but the increased winds will cause the lower atmosphere to become somewhat unsettled, giving rise to occasional showers.

The Met Office has already issued a small craft warning and this is expected to continue in place through, at least, Friday. Given the expected conditions, small craft operators should not venture far from port, especially on the windward side of the islands. Beachgoers should avoid the waters of the north and east facing beaches.

The expected strong gusts will also make some outdoor activities very uncomfortable if not dangerous. At least, light objects should be secured, as minimal storm conditions are possible. Please be guided accordingly.

The wind speed will steadily rise to 28 to 44 km/h (17 to 28 mph) by late Tuesday and continue in that range until Thursday; thereafter, subsiding. Wind gusts as high as 67 km/h (41 mph) are possible in showers. The prevailing winds will be east-northeast.

The major concern about the winds is the impact on the seas. They will cause the seas to become very hazardous, with heights reaching 4 metres (13 ft), occasionally reaching 5 metres (17 ft) late Tuesday and staying at those heights until Friday, when they will start to subside.

These conditions, especially the seas, will not be dissimilar to what would obtain during the passage of a tropical storm through the area. However, no such system will be around.

The brunt of this windy weather will be felt mainly over open waters on the windward side of the islands, windward coastlines and elevated places.

The gale-force or storm-force wind gusts and associated strong winds will be as a result of a very steep pressure gradient across the area. Recall that winds blow due to pressure differences or pressure gradients, and the greater the gradients the stronger the winds and vice versa.

The last episode of similarly strong winds and rough seas was a recent as last week.

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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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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.








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