Belize Tropical Weather Outlook: September 28, 2016

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Area wind information


Belize NMS Forecast

6:00 AM in Belize, September 28, 2016

A strong tropical wave is located about 170 miles east of Barbados and is producing winds near tropical storm force, while thunderstorm activity continues to show signs of organization. This system has a high chance of becoming a tropical depression or tropical storm later today as it moves westward to west-northwestward at 15 to 20 mph.

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


Tropical Atlantic Wide Infrared Satellite Image:

USA National Weather Service Forecast

September 28, 2016

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

A strong tropical wave is located about 170 miles east of Barbados. This disturbance is producing winds to near tropical storm force, and the associated thunderstorm activity continues to show signs of organization. Conditions are expected to be favorable for development, and a tropical depression or tropical storm is likely to form later today. The system is moving westward to west-northwestward at 15 to 20 mph, and is expected to pass over the Windward Islands later today, and move over the southeastern Caribbean Sea tonight and Thursday. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system again later this morning.

Interests in the windward and southern Leeward Islands, Bonaire, Curacao, Aruba, and along the northern coast of South America should monitor the progress of this disturbance, and consult products issued by your National meteorological service, which could include tropical storm warnings or watches. Regardless of whether the system is a tropical wave or a tropical cyclone, heavy rains and tropical-storm-force winds in squalls are expected to spread over the Windward Islands and portions of the southern Leeward Islands, beginning this morning and continuing through tonight and early Thursday.
* Formation chance through 48 hours...high...90 percent
* formation chance through 5 days...high...90 percent

A large area of disorganized showers and thunderstorms over the southwestern Gulf of Mexico just to the southeast of Tampico, Mexico, is associated with a weak low pressure system that is drifting westward. Proximity to land and unfavorable upper-level winds are expected to inhibit any significant development before this disturbance moves inland over Mexico during the next day or so.
* Formation chance through 48 hours...low...10 percent
* formation chance through 5 days...low...10 percent

Tropical Weather Discussion

...Special features...
An Atlantic Ocean tropical wave is along 54w/55w from 18n southward. A 1008 mb low pressure center is along the wave near 13n, about 250 nm to the east of Barbados. Convective precipitation: widely scattered to scattered moderate and isolated strong from 12n to 14n between 53w and 57w. The precipitation pattern continues to shows signs of organization. It is likely that a tropical depression or a tropical storm may form later today if this weather system continues to become more organized. The system is moving westward to west-northwestward 15 to 20 mph, and it is expected to pass over the Windward Islands on Wednesday morning, and then move across the southeastern Caribbean Sea late Wednesday and Thursday. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system again on Wednesday morning. Please monitor the progress of this weather system if you have any interests that are in the windward and southern Leeward Islands, Bonaire, Curacao, Aruba, and along the northern coast of South America. Please consult any bulletins and/or warnings that are issued by your National meteorological service, which may include tropical storm warnings or watches. The chance of formation during the next 48 hours is high. Gale wind conditions are imminent, within 240 nm of the center in the N and NE quadrants. Expect the sea heights to range from 10 feet to 16 feet. Please refer to the High Seas Forecast... miahsfat2/fznt02 knhc for more details.

...Tropical waves...
An Atlantic Ocean tropical wave is along 25w/26w from 17n southward, moving westward 10 to 15 knots. A 1008 mb low pressure center is along the wave near 07n. Convective precipitation: widely scattered to scattered strong from 07n to 10n between 24w and 29w.

A Caribbean Sea tropical wave along 76w/77w from 16n southward, moving westward 15 knots. The wave is to the south of Jamaica. The wave is moving into the area of an upper level trough that is along 81w. Convective precipitation: isolated moderate in the area of the trough and the cyclonic wind flow from the upper level trough.

Caribbean Sea...

An upper level trough is along 81w, from Cuba into the SW corner of the Caribbean Sea. An upper level cyclonic circulation center is near 16n81w. Convective precipitation: isolated moderate from 77w westward.

Broad upper level cyclonic wind flow also accompanies a trough, that passes through an Atlantic Ocean cyclonic circulation center that is about 250 nm to the NE of the center of Hispaniola, across Hispaniola, toward the coast of Colombia near 11n75w. Convective precipitation: rainshowers are possible between 64w and 73w.

24-hour rainfall totals in inches for the period ending at 28/0000 UTC...according to The Pan American temperature and precipitation tables...miatptpan/sxca01 knhc...0.02 in Guadeloupe.

The monsoon trough is along 09n83w at the border of Costa Rica and Panama, and westward beyond 10n90w in the eastern Pacific Ocean. Any precipitation is mixed with the 81w trough precipitation.

Weather Underground Caribbean Forecast

Tropical cyclone development is anticipated across the eastern Pacific and the Atlantic Basin on Thursday. Tropical Storm Roslyn is located about 500 nautical miles west southwest of the southern tip of Baja California, with maximum wind speeds at 45 mph (40 kts). The forecast track for Roslyn takes this system north northwestward over the eastern Pacific. By Thursday, Roslyn is expected to be downgraded to a tropical depression, with wind speeds dropping below 39 mph (33 kts). This system does not pose threats to any major land masses. In the Atlantic Basin, an area of low pressure is located roughly 410 nautical miles east southeast of Barbados. This system has a high, 90% chance to develop into a tropical cyclone as it moves west northwestward. Regardless of development, rain and thunderstorms will batter portions of the Windward Islands and the Lesser Antilles over the next 24 to 48 hours. Additionally, a cluster of showers and thunderstorms is situated over the southwestern corner of the Gulf of Mexico. This cluster of storms has a low, 10% chance to develop into a tropical cyclone as it moves inland over Mexico.


48 Hour Forecast – Favorable Environmental Conditions For Tropical Development



Infrared Satellite in Belize City

Watching low pressure near the Windward Islands
Accuweather

9/28/2016 5:50:21 AM

A strong tropical wave continues to approach the Windward Islands from the east early this morning. It is expected to bring heavy rain and gusty winds to the Windward Islands later today into Thursday. This system is expected to develop into a tropical depression later today and could be a tropical storm on Thursday or Friday. This storm will move westward across the southern Caribbean into the weekend, then make a turn toward the north or northwest. It's possible this storm will intensify into a hurricane by the end of this weekend if wind shear relaxes enough. AccuWeather meteorologists will closely monitor this feature over the coming days, and all interests in the Caribbean should monitor the progress of this system this week. The next named tropical storm will be Matthew.

Elsewhere across the Atlantic, there are no imminent threats for tropical development.



120 Hour Forecast – Favorable Environmental Conditions For Tropical Development

Invest 97-L Will Continue To Impact The Southern Lesser Antilles Today Into Tonight & Then Will Move Into The Southeastern Caribbean Tonight & Thursday
Rob Lightbown of Crown Weather Services

September 28, 2016

Invest 97-L Will Move Across The Southern Lesser Antilles Today & Into The Southeastern Caribbean Tonight & Thursday: Invest 97-L continues to gradually organize this morning and reconnaissance aircraft are now investigating this system to determine if we now have a tropical storm. So far they have found close to 45 mph surface winds and if they can find a closed surface circulation, then it will be immediately upgraded to Tropical Storm Matthew.

The wind shear over Invest 97-L has increased a little as compared to yesterday, however, it doesn’t appear strong enough to significantly impact this system. It should be noted that the environmental conditions are forecast to become quite favorable once Invest 97-L reaches the central Caribbean around Friday night and Saturday. This means that I expect slow development from today through Thursday and even Friday with the potential for fairly quick intensification starting this weekend and continuing into next week.

For Those Of You In Guadeloupe, Dominica, Martinique, St. Lucia, Barbados, St. Vincent, Grenada & Trinidad & Tobago: Tropical storm conditions, especially in squalls, will continue to impact Guadeloupe, Dominica, Martinique, St. Lucia, Barbados, Grenada and Trinidad and Tobago today and tonight. Weather conditions are expected to gradually improve during the day on Thursday.

Heavy flooding rainfall with amounts of 4 to 8 inches, strong winds with gusts of up to 50 to 60 mph and very rough seas with wave heights of up to 12 to 15 feet will all be a threat across Guadeloupe, Martinique, St. Lucia, Barbados, Grenada and Trinidad and Tobago throughout today and tonight.

For Those Of You In Aruba, Bonaire, Curacao & The Northern Coast Of Venezuela: Tropical storm and even hurricane conditions are possible starting sometime on Thursday and continuing through Thursday night and Friday. This will include heavy flooding rainfall with amounts of at least 5 to 10 inches, strong winds with gusts of up to 60 to 80 mph and very rough seas with wave heights of up to 10 to 20 feet.

The latest model guidance, including the GFS, European and Canadian models, are forecasting that a high pressure ridge could build over the eastern United States next week. This high pressure system could steer Invest 97-L westward or northwestward towards the US East Coast, Florida or the US Northern or Eastern Gulf Coast.

The GFS model continues to gradually shift westward with each new forecast run. The latest forecast from the GFS model forecasts that this system may turn to the north along 75-76 West Longitude impacting Jamaica on Sunday, eastern Cuba on Monday and much of the Bahamas on Tuesday. From there, the GFS model now forecasts that this system will be a significant hurricane hit from the Carolinas northward through Virginia, Maryland, New Jersey, Long Island and southern New England from Wednesday night to Friday.

The Canadian model guidance also forecasts a significant impact to eastern Jamaica on Sunday, then to eastern Cuba on Sunday night and the northern Bahamas on Monday. From there, the Canadian model guidance forecasts a path that takes it over the outer banks of North Carolina next Wednesday and then south of New England late next week.

The European operational model forecasts the northward turn to occur around 77.5 West Longitude with a direct impact to Jamaica on Monday night and eastern Cuba on Wednesday. From there, the European model forecasts that this system could slow down in forward speed and turn northwestward in the Bahamas as a high pressure system builds to the north of it. If this happened, it would mean a substantial threat to Florida and the eastern Gulf of Mexico next weekend.

The European ensemble model spread implies a potential serious threat to Jamaica and Cuba on Monday and Tuesday and then to Florida and the Bahamas late next week.

One key factor in determining the ultimate final track of Invest 97-L could occur during Friday and Saturday as all of the model guidance are forecasting a turn to the west-southwest. How far west this system gets by Sunday will determine who is impacted next week. The European model is further south and west than the GFS model. So, a further west track in the Caribbean would mean a Florida and Gulf of Mexico impact. If Invest 97-L doesn’t get as far west as the European model suggests, then the big threat would turn to the US East Coast.

Here Are My Thoughts: I still think that Invest 97-L will probably wait to really start ramping up in intensity until it gets into the central Caribbean this weekend. Once this happens, then I think that we should probably see it become a hurricane late this weekend or early next week and then continue to strengthen even further during next week. It needs to be pointed out that the environmental conditions could be very favorable for strengthening this weekend into next week and thus rapid intensification is definitely a possibility with the potential for a serious hurricane to possibly impact Jamaica, parts of Hispaniola and parts of Cuba around early next week.

The track forecast of Invest 97-L for next week and beyond continues to be extremely uncertain. An upper level low pressure system is forecast to dive into the Ohio Valley over the next couple of days and then gradually weaken and lift northeast into southeastern Canada and New England by late this weekend and early next week. In addition, another trough of low pressure is forecast to push east and northeast from the Plains States into the eastern United States next week. The evolution of these two weather systems will be crucial in determining the ultimate forecast track of Invest 97-L. I continue to see a few possible scenarios:

The first potential scenario is that the upper level low pressure system is able to split as it pushes northeast this weekend leading to Invest 97-L to be yanked out of the Caribbean and sent northward along the US East Coast impacting areas from eastern Florida through the Carolinas from Tuesday to Thursday and then the Mid-Atlantic states and southern New England late next week. I give this first scenario a 45 percent chance of happening.

The second potential scenario is that the upper level low pressure system initially is able to pick up Invest 97-L to near the north coast of Cuba or the western Bahamas by the middle part of next week before that upper level low weakens and dissipates as it pushes east. Once this happens, a ridge of high pressure could build to the north of Invest 97-L late next week turning this system west or northwestward and directly impacting Florida and the eastern Gulf of Mexico next weekend. I give this second scenario a 40 percent chance of happening.

A third possible scenario is that the upper level low pressure system weakens and dissipates as it moves into Atlantic Canada by early next week and a new upper level ridge of high pressure builds over the eastern United States towards the middle part of next week. This could cause Invest 97-L to be guided into the northwestern Caribbean or southeastern Gulf of Mexico around Thursday of next week. I give this third scenario a 15 percent chance of happening.

These three scenarios mean that once Invest 97-L reaches the central Caribbean this weekend, the uncertainty with where it could ultimately track next week becomes extremely high.

Everyone in the Caribbean, including Hispaniola, Cuba, Jamaica, the Cayman Islands, Belize and the Yucatan Peninsula should keep a very close eye on the progress of Invest 97-L. It may be a very good idea to look through your hurricane preparedness kits as soon as possible to make sure you have everything stocked up. Be aware that there is the potential for a strong and dangerous hurricane to be tracking across the Caribbean this weekend into next week.

Turning to those of you on the US East Coast, the Eastern US Gulf Coast and the Bahamas – For now, just keep a very close eye on the progress of this system as any potential impact on the United States probably will not happen for another 7 to 10 days from now. It should be noted, however, that the chances for a United States impact from this system are now increasing and is something to really watch.

Invest 97L Information:


Model Track Forecast:

Courtesy of Weather Underground

Satellite Imagery:



97L Approaches Tropical Storm Strength
Jeff Masters

September 27, 2016

Air Force Hurricane Hunters were unable to find a closed circulation in the midst of Invest 97L, but the system is still on the verge of becoming a tropical storm. Flight-level winds at 2034Z (4:34 pm EDT) were sustained at up to 36 knots (41 mph) on the northwest side of 97L. This translates to ground-level sustained winds of around 32 knots (37 mph), or just below the 39-mph threshold for tropical storm formation. However, a tropical wave cannot be classified by NHC as a tropical depression or tropical storm until it has a closed circulation. The lack of a fully closed circulation was manifested in much weaker winds on the south side of 97L. Southwest winds at flight level were only about 5-6 knots, and no significant westerly winds were found.


Figure 1. Enhanced infrared image of Invest 97L at 2115Z (5:15 pm EDT) Tuesday, September 27, 2016. Image credit: NASA/MSFC Earth Science Office.

It shouldn’t take too much longer for 97L to close off a circulation and intensify enough to become Tropical Storm Matthew. Satellite loops showed that showers and thunderstorms were increasing in coverage and strength in the core of 97L. The system’s upper reaches are well ventilated, with excellent outflow supporting the continued growth of thunderstorms. The usual nighttime maximum in shower and thunderstorm activity could be enough to give 97L a name. In a special outlook issued at 4:20 pm EDT Tuesday, the National Hurricane Center gave 97L a 90% chance of becoming at least a tropical depression by Thursday afternoon.

The outlook for 97L
As we discussed this morning, 97L has a long road ahead of it, with many twists and turns possible over the next week or more. Models continue to support the idea that fast-moving 97L will sweep through the Lesser Antilles on Wednesday, possibly as a strong tropical storm. The strongest winds and heaviest rains of 4 - 8”, with locally higher amounts, can be expected over the islands just north of where the center of 97L is, including the islands of St. Lucia, Martinique, Dominica, and Guadaloupe. The storm will continue westwards on Thursday, and make its closest approach to the ABC islands of the Netherlands Antilles--Aruba, Bonaire, and Curacao--on Thursday night and Friday morning. These islands will be on the weak (left) side of the storm, and may escape receiving tropical storm winds. However, heavy rains of 2 - 4” can be expected, as predicted by the 12Z (2 am EDT) Tuesday run of the HWRF model (see Figure 2).


Figure 2. Cumulative rainfall projected by the 12Z Tuesday run of the HWRF model through Sunday afternoon, October 2. Image credit: NOAA/NWS/NCEP.

As it moves into the southeast Caribbean--a challenging place for tropical cyclones, due to persistent sinking air--97L may struggle. Models are in fairly close agreement that 97L’s track will bend slightly toward the west or even southwest in the Caribbean, which could bring the center fairly close to the northern coast of Venezuela, leading to interaction with land that would hinder its growth. Toward the weekend, it appears that an upper-level low over the eastern U.S. will provide an opening for 97L to make a very sharp northward turn. As it enters the central Caribbean, 97L may have a better opportunity to intensify, and residents of the Greater Antilles--including Cuba, Haiti, Jamaica, and the Dominican Republic--will need to keep a close eye on it. While a sharp right-hand turn might seem implausible, there are a number of cases of storms taking such a northward bend, especially in October, with the classic example being 1954’s Hurricane Hazel (see Figure 3 below).

The 12Z runs of the GFS, UKMET, and European models--our best three long-range track models--all support the idea of 97L moving north from the Caribbean into the Bahamas, as soon as Monday of next week (GFS) or as late as Wednesday (UKMET and Euro). Whether or not the U.S. East Coast is threatened by 97L will depend on how soon the expected northward turn occurs and on the evolution of this weekend’s upper-level trough. These factors are too far out to be predicted with any confidence. The same is true for 97L’s eventual peak intensity, although the waters of the Caribbean and northwest Atlantic are at record or near-record warmth, more than capable of supporting a powerful hurricane if the atmospheric preconditions fall into place.


Figure 3. A comparision of the track of 1954’s Hurricane Hazel (left) with the GEFS ensemble model tracks for 97L produced at 18Z Tuesday (left). These ensemble members are produced by running the same model for the same period, each time varying the starting-point conditions in order to simulate the uncertainty in our observations of the atmosphere. The idea is not that 97L will mimic Hazel but that the sharp right-turn depicted by the GEFS does have a precedent.


Sept. 27: 97L Slow to Develop – Could Bring Tropical Storm Conditions to Windward Islands and Southern Caribbean



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Tropical Atlantic Wide Visible Satellite Image





Edited by Marty (56 minutes 50 seconds ago)