Here We Go Again – It’s Hurricane Season 2017; What’s the Forecast?

2 06 2017

Dale C. S. Destin |

When you live in “Hurricane Alley” like we do, you often don’t want to think about the hurricane season before it starts – it’s too stressful. But you really should, as preparation is key to survival. If you are now preparing for the 2017 Atlantic hurricane season, you are late, but there is still some time left.

What to prepare for – What’s the forecast?

Key to your preparations is to know what to prepare for. From this vantage point, we will most likely have a near normal hurricane season. Normally, the season has 12 named storms (tropical storms and hurricanes), 6 hurricanes and 3 major hurricanes. This year, our ensemble (mean) forecast is for 14 named storms, 7 hurricanes and 3 major hurricanes.

2017JuneHurricaneSeasonForecast1

A better indicator of the activity for the season is the accumulated cyclone energy (ACE) index. This is a measurement of the potential of wind and storm surge destruction of a named storm. Summing together the ACE index of each named storm, provides a more complete picture of activity for a season, outside of just the number of storms. The mean ACE index forecast for this year is 110; the average is 106 (1981-2010).

The latest forecast represents an uptick in the activity for the season. The previous forecast called for a below normal hurricane season – 11 named storms, 6 becoming hurricanes and 3 major hurricanes, with an ACE of 71. This was predicated on the forecast of an El Nino during the heart of the season.

El Nino normally inhibits tropical cyclone (tropical depression, tropical storm and hurricane) activity. However, over the past few months, an El Nino seems less likely, delayed or insignificant, if developed; hence, the uptick in the activity for the season.

Also, contributing to the uptick in the forecast activity for the season is the forecast of warmer than normal sea surface temperatures across the tropical north Atlantic and lighter than normal trade winds. All things relish by tropical cyclones.

2017HurricaneNames

Our forecast is the ensemble (mean) of the forecasts from Klotzbach of Colorado State University, the U.S. National Oceanic and Atmospheric Administration (NOAA), Saunders and Lea of Tropical Storm Risk.com (TSR), the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF), UK Met Office and The Weather Company (TWC).

It must be noted that NOAA is the only group, of the five surveyed, that is forecasting an above normal season.

So, that’s the forecast – what is the probability of Antigua being hit?

The probability of Antigua being hit or brushed by one or more named storm this year is around 63% – up 14% from the average of 49%. The probability of one or more hurricanes is 22% – down 15% from the average of 37%.

These numbers were calculated based ONLY on the likely best similar years (1957, 1969, 1979 and 2006) to the upcoming hurricane season according to Klotzbach. Of these years, we were hit by Tropical Storms Claudette, Frederic and Chris and brushed by Hurricane David.

Notwithstanding, at the end of the day, these numbers don’t mean a whole lot. We could be hit by one or more named storms or none at all. Bottomline – we truly do not know what is going to happen, with any certainty. However, what we do know, with absolute certainty, is that storms and hurricanes form every year, and we could get hit, as we have many times in the past. So, regardless of the probabilities and forecasts, we need to prepare. It only takes one tropical cyclone to set you back for years.

A season can produce many storms, but have little impact, or produce few storms and have one or more hitting Antigua with major impact.

Antigua averages one hurricane every three years and one named storm every two years or every other year.

What happened last season – 2016?

The 2016 season was more active than normal – the first active season since 2012 and the most active since 2010. It spawned 15 named storms, 7 became hurricanes and 3 reached major hurricane status. The strongest hurricane for the season was Matthew, which had peak sustained winds of 258 km/h (160 mph).

Satellite Image of Hurricane Matthew - Sep 30, 2016

Satellite Image of Hurricane Matthew – Sep 30, 2016

Hurricane Matthew also caused the most devastation. In total, up to 600 deaths have been attributed to the system, including over 500 in Haiti, making it one of the deadliest Atlantic hurricanes.

Hurricane Matthew 2016

Rainfall Trail From Hurricane Matthew 2016

The 2016 season is the first year since 2008 that no tropical cyclone hit or brushed Antigua. It was likely the least stressful hurricane season for the island in, at least, eight years.

The 2017 season is forecast to be similar to 2016.

The hurricane season runs from June 1 to November 30.

Follow us and stay updated on the latest via our social media platform, which includes twitter, facebook, wordpress, instagram, tumblr, and google+. Follow us also for all things weather and climate.

Advertisements




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.





The 2017 Atlantic Hurricane Season Early Forecast

7 04 2017

Dale C. S. Destin |

Good news! The early forecasts just issued for the upcoming 2017 Atlantic hurricane season (AHS) indicate a below normal season is most likely. This is forecast to be most evident in the number of hurricanes that forms (see graphic below). It could be as quiet as the 2014 and 2015 seasons. Nevertheless, the usual complete preparations are still very much required.

Ensemble forecast

The ensemble (mean) forecast, based on predictions from Klotzbach of Colorado State University, Saunders and Lea of Tropical Storm Risk.com (TSR) and AccuWeather.com, is for 11 named storms, 4 becoming hurricanes and 2 becoming major hurricanes.

2017HurricaneSeason

A better indicator of the activity for the season is the accumulated cyclone energy (ACE) index which is a measurement of the strength and duration of each tropical cyclone. Summing together the ACE of each cyclone, provides a more complete picture of how active the season is likely to be outside of just the number of storms.

This year, the ensemble forecast calls for an ACE index of 71. If this forecast pans out, the 2016 season would be around 30% less active than normal.

It must be noted though that there is very low skill in forecasting the AHS (June to November) in April. However, this is the best available forecast for the season, from this vantage point, and can be used as a guide for what is possible. A more skilful forecast will be available around June 1.

El Nino

 The development of an El Nino is the main climate factor that is forecasts to cause the hurricane season to be quieter than normal. El Nino is virtually synonymous with inactive AHSs, as it causes unfavourable conditions for tropical cyclones (tropical depressions, tropical storms and hurricanes). The main one being the creation of strong winds aloft that inhibits or rips tropical cyclones apart.

However, regardless of the above probabilities and forecasts, this is not a licence to do anything differently for this hurricane season. The same comprehensive preparations are required to deal successfully with any eventuality. It only takes one tropical cyclone to set you back for years. Recall – Gonzalo struck us in a quiet year – 2014.

New and improved products

As is the case annually, there are new and improved products that will be on show. The most significant of which will be the issuing of watches, warnings and advisories for potential tropical cyclones.  A potential tropical cyclone is being defined as a disturbance that has the potential to produce tropical storm or hurricane conditions to land areas within 48 hours.

This new product is expected to be a game-changer as it will eliminate surprise storms and hurricanes and increase the lead time for preparations for rapidly developing disturbances approaching land. If such a product were in place for Gonzalo of 2014, Antigua would have likely fared much better.

Click here for other new and improved products.

2016 hurricane season summary

The 2016 AHS was active – the first active (above normal) season since 2012 and the most active since 2010, based on the ACE index. It produced 15 named storms. Of the 15, 7 became hurricanes and 4 reached major hurricane status – at least Category 3 on the Saffir-Simpson Hurricane Wind Scale. The strongest tropical cyclone for the season was Major Hurricane (MH) Matthew with peak winds of 160 mph and minimum pressure of 934 millibars.

Hurricane Matthew caused the most devastation. In total, up to 600 deaths have been attributed to the storm, including over 500 in Haiti, making it the deadliest Atlantic hurricane since Stan in 2005.

The 2016 season is the first year since 2008 no tropical cyclone passed within 121 miles of Antigua. It was likely the least stressful AHS for the island in, at least, eight years.

Follow us and stay updated on the 2017 AHS via our social media platform, which includes twitter, facebook, wordpress, instagram, tumblr, and google+. Follow us also for all things weather and climate.





A Severely Dry February for Antigua

22 03 2017

Dale C. S. Destin |

February 2017 was a severely dry month for Antigua. It is the fourth driest February on record, dating back to, at least, 1928. Only one other February has been drier since 1983 – that of 2013.

Top4DriestFebForAntigua

On average, such an extremely low rainfall only occurs once in around every 33 years for February. In other words, there is only a 3% chance of such little rainfall taking place for the month.

The island-average for the February was just 14.0 mm (0.55 in). This makes it the driest and first below normal rainfall month since October 2016.

One month of dryness does not say anything about the rainfall for the upcoming months. However, with the probability of an El Nino rising, this dryness may be a sign of unwelcome things to come.

Recall the El Nino reduces rainfall activity across our area, mainly during the wet season, while the opposite – La Nina has reverse effect. It is still early days as to whether El Nino will develop but not too early for us to start to put contingency plans in place.

On average, February is our second driest month on, with an island-average of 55.9 mm (2.20 in).

Based on rain gauge measurement and satellite estimates, Barbuda fared slightly better with a total in the range of 12.7 to 38.0 mm (0.5-1.5 in).

Thus far, March is on track for, at least, near normal rainfall.

Follow us for all you need to know about our rainfall and all things weather and climate. We can also be followed on twitterfacebookinstagramtumblrflickrgoogle+, and youtube.





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.

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





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.








%d bloggers like this: