Belize Tropical Weather Outlook: September 20, 2018

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Area wind information

Belize NMS Forecast

September 20, 2018

Tropical cyclone formation is not expected in the North Atlantic, the Caribbean Sea or the Gulf of Mexico during the next 48 hours.

USA National Weather Service Forecast

September 20, 2018

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A concentrated area of thunderstorms associated with a westward- moving tropical wave is located about 850 miles east of the Windward Islands. Although this disturbance shows some signs of organization on satellite imagery, there is no evidence of a surface circulation at this time. Some additional development is possible today before upper-level winds become highly unfavorable for tropical cyclone formation starting tonight and continuing through the weekend.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...20 percent.

A non-tropical low pressure system is forecast to develop by Friday night over the central subtropical Atlantic Ocean between Bermuda and the Azores. Conditions are expected to be conducive for the low to acquire some subtropical or tropical characteristics, and a subtropical or tropical cyclone could form over the weekend or early next week while the low meanders over the central Atlantic Ocean.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...40 percent.

Tropical Weather Discussion

...Tropical Waves...

An Atlantic Ocean tropical wave is along 21W/23W from 20N southward. This wave is associated with a distinct 700 mb trough. Isolated moderate rainshowers are from 10N to 20N between Africa and 23W.

An Atlantic Ocean surface trough is along 19N29W 10N31W. Rainshowers are possible within 360 nm to the east of the trough, and within 300 nm of the western side of the trough. The trough is associated with a distinct 700 mb trough.

An Atlantic Ocean surface trough is along 46W/48W, from 05N to 13N. Scattered to numerous strong rainshowers are from 09N to 11N between 46W and 48W.

A Caribbean Sea tropical wave is along 66W/67W from 20N southward, moving across the western part of Puerto Rico. Widely scattered moderate to isolated strong rainshowers are from 20N southward between 62W and 70W. A large area of SAL follows this wave, from the Leeward Islands to 50W. This area eventually will spread westward, across the eastern Caribbean Sea islands, bringing hazy skies and stable conditions.

...The Caribbean Sea...

An upper level trough passes through the Atlantic Ocean, through the Windward Passage, into the SW corner of the Caribbean Sea near the coasts of Costa Rica and Panama. Isolated moderate to locally strong rainshowers are from 16N southward from 79W westward. Rainshowers are possible from 16N northward from 79W westward.

An eastern Caribbean Sea tropical wave, along 67W, will move westward, across the central Caribbean Sea from Thursday into Friday. The wave will pass to the west of the area through late Saturday into Sunday. Strong gusts are possible near rainshowers, that are associated with this tropical wave near the Lesser Antilles and eastern Caribbean Sea through this evening. High pressure building from the central Atlantic Ocean into the central Bahamas will support moderate to fresh trade winds and building seas across the entire basin from late on Wednesday through Friday.

Climate Prediction Center's Central America Hazards Outlook

48 Hour Forecast - Favorable Environmental Conditions For Tropical Development

Infrared Satellite in Belize City

Watching a couple areas across the Atlantic

September 20, 2018

There are no organized tropical systems across the Atlantic at this time, but we are watching a couple areas for potential development over the next several days.

The first area we are monitoring is a tropical wave located around 800 miles to the east of the Windward Islands. Current satellite imagery shows a concentrated area of showers and thunderstorms associated with this tropical wave as it continues to track off to the west. There is a small chance this wave could develop further over the next day or so until it moves into a zone of higher wind shear, which would inhibit further development and organization.

Elsewhere in the basin, we are watching a non-tropical area of low pressure over the central Atlantic that is expected to develop this weekend. Conditions may become favorable enough for a subtropical or tropical cyclone to form as the low moves through the central Atlantic.

120 Hour Forecast - Favorable Environmental Conditions For Tropical Development

Two Tropical Disturbances Between The Coast Of Africa & The Lesser Antilles Have A Chance Of Developing; Tropical Development Near Bermuda Is Possible This Weekend
Rob Lightbown of Crown Weather Services

September 19, 2018

Two Tropical Disturbances Between The Lesser Antilles & The Coast Of Africa: There are a couple of tropical disturbances between the coast of Africa and the Lesser Antilles that need to be watched for potential tropical development in the coming days.

The first tropical disturbance is currently located about 1000 miles or so to the east of the Windward Islands. Satellite imagery indicates that there is some sort of circulation associated with this disturbed weather and for now it’s within a region of favorable environmental conditions. This means that some development is possible today through Thursday, however, it appears that this disturbance will be yanked to the northwest as we get into Friday and this weekend. Once this happens, this tropical disturbance will encounter unfavorable environmental conditions and any additional development would be highly unlikely.

At this point, the first tropical disturbance poses no threat to the Lesser Antilles.

There is a second tropical disturbance embedded within the Inter-Tropical Convergence Zone. This disturbance is currently located to the southwest of the Cape Verde Islands between 25 and 30 West Longitude and this system is likely to push westward over the next several days. The environmental conditions along the forecast path of this disturbance are favorable for development and we are going to have to keep an eye on it. There is the possibility that this second disturbance could develop into a tropical depression or a tropical storm before it reaches Barbados and the Windward Islands in about a week or so from now. This means that everyone in the Windward Islands and on the island of Barbados should closely monitor the progress of this second disturbance – It is not an immediate threat, however, it is something to keep an eye on. At this point, only the FV-3 GFS experimental model forecasts development before it reaches the Windward Islands while the other model guidance members keep this system a strong tropical disturbance.

This second tropical disturbance is one that requires close watching for the Caribbean. The reason why is this disturbance now located over the eastern Atlantic could be the trigger for tropical development in the western Caribbean around the first week of October.

As this tropical disturbance pushes into the Caribbean late next week and next weekend (September 28-30), it will encounter a upward motion pulse of the Madden Julian Oscillation that will be pushing into the Atlantic Basin around that time. This upward motion pulse will help to increase moisture and increase convection across the Caribbean and the tropical disturbance could provide the trigger to set off tropical development in the western Caribbean around the first week of October.

The long range GFS, FV3-GFS experimental and GFS ensemble model guidance continue to forecast some sort of tropical development to occur in the Caribbean at the very end of this month and the very beginning of October. The model members do vary on where tropical development may occur. The GFS model forecasts that the tropical development might occur in the central Caribbean on October 1. The GFS ensemble guidance shows a trend towards western Caribbean tropical development during the first week of October. The FV3-GFS experimental model forecasts a tropical storm in the northeast Caribbean next weekend that heads for the Bahamas during the first few days of October.

The European operational model forecasts no tropical development in the Caribbean for the next 10 days. The European ensemble guidance does have about a quarter of its members forecasting western Caribbean tropical development during the first week of October.

Bottom Line Is That the second tropical disturbance that is now located to the southwest of the Cape Verde Islands has the potential to become a tropical depression or a tropical storm at some point in the Caribbean either at the very end of this month in the eastern Caribbean or in the western Caribbean during the first week of October.

Where this system tracks will depend heavily on where exactly it forms. If it develops in the eastern Caribbean, then a track towards the Bahamas and near the US East Coast could be in the cards. On the other, if this system waits to develop until the western Caribbean, then a track into the central and eastern Gulf of Mexico would become more likely.

The potential for Caribbean tropical development at the end of this month and during the first week of October is something that I will be monitoring very closely and I will keep you all updated.

Tropical Development Possible Near Bermuda Next Week: I am keeping an eye on a frontal boundary that is pushing off of the US East Coast. In particular, there is the potential for some sort of sub-tropical or tropical system to spin up along the tail end of this front as it nears Bermuda on Thursday into Friday. In addition, there is the possibility that this system could loop back around to the west and head back towards the US Southeast Coast next week.

The GFS and European model has a scenario that consists of this system heading way out to near 50 West Longitude before it loops back and tries to head for Atlantic Canada late next week. Meanwhile, the UKMET model forecasts a quick loop back towards the US Southeast Coast early next week. Remember, the UKMET model was one of the first models to forecast that Florence would track quite far west in longitude – even though it was too far south with the overall track, it did show the possibility first.

Looking at the ensemble guidance, more of the ensemble members forecast a track to the east way past Bermuda. There are a couple of ensemble members that try to bring this system back towards the US Southeast Coast.

At this point, I think the part that we are most sure about is that a low pressure system will impact Bermuda on Thursday into Friday with heavy showers and gusty winds. There is the possibility that it may try to acquire tropical or sub-tropical characteristics this weekend. Beyond this, we will have to watch carefully to see if this system tries to turn back towards the west and head for the US Southeast Coast late this weekend into next week. Even if this system does loop back towards the US Southeast Coast, it will likely be quite weak in strength.

After Florence: What's Next in the Atlantic?
Jeff Masters, Category 6

September 20, 2018

The remnants of Florence moved off the Northeast U.S. coast on Tuesday as an elongated zone of low pressure. We may not have seen the last of Florence, though. As a high-latitude upper low stretches out the zone of ex-Florence’s low pressure zone even more, there is the potential for two powerful low pressure systems to develop from Florence’s remnants, with one of them transitioning to a tropical or subtropical storm.

The other area of interest NHC is watching--a tropical wave about 1000 miles east of the Lesser Antilles Islands--appears weak and disorganized on satellite imagery, and has little model support for development. In their 2 pm EDT Wednesday Tropical Weather Outlook, NHC gave this system 2-day and 5-day odds of development of 10%.

Recent runs of the GFS model and its ensembles, plus some ensemble members of the European model, have been suggesting that a tropical wave predicted to emerge from the coast of Africa on Friday might be a threat to develop late next week near the Lesser Antilles Islands. That’s a far-future low-probability forecast, but a reminder that we are still in the peak part of the Atlantic hurricane season, and we still need to watch tropical waves coming off the coast of Africa.

CLICK HERE for the website for Belize National Emergency Management Organization (NEMO)

Last edited by Marty; Yesterday at 05:48 AM.