Very Hazardous Marine Conditions for Antigua and Barbuda

14 01 2017

Dale C. S. Destin |

 

High Surf

High Surf

The shoreline Antigua and Barbuda and the rest of the northeast Caribbean are getting hammered by high surfs. Additionally, starting today, seas in open waters will become very unfriendly to small craft operators. As a result, the weather authority in Antigua and Barbuda has issued special marine statements on the high surfs and rough seas.

Surfs are building – they are expected to range 8-12 feet (2.4-3.6 m) between today and Monday, affecting mainly northern and eastern coastlines. These high surfs are being generated by a low pressure system located just northeast of the area, which is pushing very large swells to our shores.

There is a high risk of rip currents, especially over the next 24 hours when the surfs are expected to peak. Rip currents are powerful channels of water flowing quickly away from shore, which occur most often at low spots or breaks in the sandbar and in the vicinity of structures such as groins such as jetties and piers.

The winds will become fresh to strongthey will frequently be in excess of 18 mph (16 knots) from today to Wednesday. The winds will peak at around 30 mph (22 knots) with occasional gale-force gusts to the around 39 mph (34 knots) today and Sunday likely.  These winds will primarily take place over open waters, coastal areas on the northern and eastern side of the islands and elevated areas.

windjan142017

windgustsjan142017

The seas will respond to the winds – they will become very rough, rising to as high as 3.6 metres (12 feet) on Saturday night Sunday. Waves will decrease to less than 2.0 metres (6 feet) by Wednesday.

seasjan142017

The cause of the strong winds – this is due to a significantly tight of the pressure gradient (horizontal differential of pressure) across, which will tighten a bit more over the next 24 hours. The relatively tight pressure gradient is in response to a strong high pressure system moving from west to east across the Atlantic from the United States. There are NO tropical cyclone (tropical depression, tropical storm or hurricane) in the area.

Surface Chart

Surface Chart for Saturday 8 am, Showing a Tight Pressure a Tight Gradient as Evident by the Closeness of the Isobar (Pressure Lines)

Precautions – Sea-bathers should avoid the waters, mainly on the northern and eastern sides of the islands until Tuesday. Small craft operators should not venture far from port through Monday.

A high surf warning means that high surf will affect beaches in the advisory area, producing beach erosion and dangerous swimming conditions.

A small craft advisory means that wind speeds of 24-38 mph (21 to 33 kt) and or seas of 7 feet (2.1 m) or greater are expected to produce hazardous wave conditions to small craft. Inexperienced mariners, especially those operating smaller vessels should avoid navigating in these conditions.

The strong winds, especially if frequently gusting to gale force, could also make some outdoor activities very uncomfortable if not hazardous, please be guided accordingly.

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4 responses

14 01 2017
Joe Bahri

Come on, Dale.
How could you focus so exclusively on wind and wave without even mentioning the effects on temperature? You did the same thing on TV mid week.
A northerly wind flow……created by the relatively western position of the high……is unusual by itself and worthy of comment and explanation.
But also, night time lows in the mid sixties DEMAND discussion and linkage to the wind speed and direction even if the focus is on the waves. 66 degrees F is lower than most people set their AC UNITS!

You might think that saying NORTH winds bring cold Temps while SOUTH winds bring warm Temps is stating the obvious, but it is amazing how many people do not understand this.

Joe

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15 01 2017
Dale C. S. Destin - Antigua Met Service

Thanks for your feedback and a happy new year, but come on, Joe:

How could I have discussed temperatures in a blog that was designed to talk about hazardous marine conditions? Clearly that would be misplaced.

Regarding your critique of my television presentation with respect to temperature. There is nothing unusual happening with temperatures to the best of my knowledge. The only difference this year is that we have five other stations apart from the one at the Airport that are providing us with temperature data. And so we are now able to report a min and max temp for Antigua as opposed to just the Airport.

These stations are verifying what we knew but had not empirical data to prove – the Airport neither gets the warmest day-time highs nor the coolest night-time lows due to its proximity to the ocean and location on the windward side of the island. If you want an explanation for the min temp, you should also be asking for one for the max also, as it has not fallen below 30C/86F based on the new stations. However, at the Airport, the mean max and min for Jan are 28C and 22C respectively.

Please keep in mind that the reported min temp for any given night is not what is measured for every place on the island. Various parts of the island will have it’s own min but we report the lowest min measured. The converse is true of the max temp.

Lastly, FYI: We are being ask to reduce TV presentations to no more that 3 mins, so there is no room for discussions, we have to prioritize what needs to be presented and try to make it fit into the limited time.

Thanks for your feedback Joe and all the best!

Dale

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15 01 2017
Joseph Bahri

Come on, Dale.
That has been my main problem with weather forecasting here for years, as you well know.
You CANNOT or SHOULD NOT ever seek to isolate components of weather as they are ALL interrelated. The temperature and unusual wind direction should have been mentioned and would not have been out of place.
The same systems/conditions (high pressure to the west, low pressure with trailing cold front further east and tight pressure gradient in between) which brought about the hazardous marine conditions ….high winds and dangerously high seas……………..these same systems/conditions were responsible for bringing in the most unusual NNE wind flow and the exceptionally cool night time lows.
If you are so insistent on sticking to the Blog’s topic (which YOU chose to give)…Very Hazardous marine conditions…………..then your last paragraph about the gale force winds affecting outdoor activities presumably on land (very uncomfortable if not hazardous) is also MISPLACED (your word, not mine).

And come on, Dale.
The Nights have been much cooler BECAUSE of the wind.
Usually, in Antigua, it is the LACK of wind (light to variable) with clear skies that brings radiational cooling and cooler nights. But in this case, the strong NNE wind flow brought about the cooler than average night time lows.
In Jamaica, they use to call these conditions “northers”, the cold crisp wind behind a cold front. But it is unusual this far east and south of the American continent.
How can you possibly say that there was nothing unusual about the low temperatures? When was the last time your Met Office reported 66 and 68 as night time lows? I take your point about the additional stations reporting greater extremes, but I have lived on Market Street for all my 56 years from birth, and I don’t ever remember feeling the chilly wind as cool as this before, with or without “empirical data”.

And come on, Dale………………you are going to stand by and allow someone to “reduce” the sacred weather report to three minutes…………..three minutes!!! There are commercials on ABS that are longer!! No way…you have to fight this. Weather MUST be reported and DISCUSSED and EXPLAINED. It is a teaching tool for our students. It is part of the information for our Tourism product. It is vital news source for fishermen and those who plan outdoor activities. I would rather take it off the air completely than suffer the humiliation of having it reduced to 3 minutes. Shameful!!!
Reducing the time of presentation in not the way to improve it. And I will be happy to suggest ways of improving it, as I have done before.

Thanks for your attention.
Joe

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16 01 2017
Dale C. S. Destin - Antigua Met Service

Joe, thanks for your feedback.

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