Belize Tropical Weather Outlook: August 24, 2016

(Hit "reload" or "refresh" page" from your browser's VIEW menu to be sure you are seeing the latest maps...)





Area wind information


Belize NMS Forecast

6:00 AM in Belize, August 24, 2016

At 3:00am Tropical Storm Gaston was located over the central Tropical Atlantic near lat 14.9N lon 38.6W, or about 975 miles west of the Cabo Verde Islands. Gaston was moving west-northwest at 17 mph with maximum sustained winds of 70 mph.
-A broad area of low pressure near Guadeloupe, associated with a tropical wave, is slowly becoming better organized and has a medium chance of becoming tropical depression during the next day or two.

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

August 24, 2016

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

The National Hurricane Center is issuing advisories on Tropical Storm Gaston, located several hundred miles west of the Cabo Verde islands.

Satellite images, surface observations, and radar data from the Lesser Antilles indicate that a broad area of low pressure associated with a tropical wave is located near Guadeloupe. Although environmental conditions are only marginally conducive for development, this system could become a tropical depression during the next day or two while it moves west-northwest at 15 to 20 mph across the Leeward Islands and the Greater Antilles. Conditions could become more conducive later this week while the system moves near the southeastern and central Bahamas. An Air Force Reserve hurricane hunter aircraft is scheduled to investigate this disturbance later today, if necessary. Interests from the islands of the northeastern Caribbean Sea to the Bahamas should continue to monitor the progress of this system. Gusty winds, heavy rains, and possible flash floods and mudslides could occur over portions of these areas regardless of tropical cyclone formation. Please consult products issued by your local meteorological offices for further details.
* Formation chance through 48 hours...medium...50 percent
* formation chance through 5 days...high...70 percent

Tropical Weather Discussion

...Special features...
Tropical Storm Gaston is centered near 14.7n 37.1w at 24/0300 UTC or about 760 nm west of the Cabo Verde islands moving west- northwest at 15 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate to isolated strong convection is from 13n-16n between 35w-39w. Isolated moderate convection is from 11n-13n between 35w-39w. Please see the latest NHC intermediate public advisory under AWIPS/WMO headers miatcpat2/wtnt32 knhc and the full forecast/advisory under the AWIPS/WMO headers miatcpat2/wtnt22 knhc for more details.

A tropical wave west of the Lesser Antilles is analyzed from 22n64w through a 1009 mb low near 16n60w to 11n57w. This system could become a tropical depression during the next day or two as it moves west-northwest 13 to 17 kt. Conditions could become more conducive later this week while the system moves near the southeastern and central Bahamas. Scattered moderate to isolated strong convection is within 90 nm either side of the wave axis between 15n-19n. Isolated moderate convection is within 90 nm either side of the wave axis between 14n-16n and 19n-21n. There is a medium chance of tropical formation in the next 48 hours. Interests from the islands of the northeastern Caribbean Sea to the Bahamas should continue to monitor the progress of this system. Gusty winds, heavy rains, and possible flash floods and mud slides could occur over portions of these areas regardless of tropical cyclone formation.

...Tropical waves...
The tropical wave in the West Bay of Campeche has moved inland over Mexico and is no longer in the Gulf of Mexico basin. Lingering moisture over south Mexico continues to generate scattered showers and isolated thunderstorms inland and within 45 nm along the coast between 94w-96w.

Caribbean Sea...

The primary concern tonight is the approaching tropical wave east of the Lesser Antilles. Please see the special features section above. An elongated upper low is centered in the west Caribbean near 17n83w and extends an upper trough northwest across the Yucatan Peninsula into the Gulf of Mexico and southeast to Colombia. Clusters of scattered showers and isolated thunderstorms are within 120 nm along the South Coast of Cuba west of 75w and along the East Coast of the Yucatan north of 18n. An upper ridge anchored east of the Lesser Antilles dominates the remainder of the Caribbean tonight. Scattered showers and possible isolated thunderstorms are now moving over the islands of the Lesser Antilles, Virgin Islands, and Puerto Rico ahead of the tropical wave in the special features above. Showers and thunderstorms that developed earlier this evening over portions of Hispaniola are now over south Haiti and into the Caribbean waters from 17n-19n between 72w- 75w. Isolated showers and thunderstorms are in the southwest Caribbean within 90/120 nm along the coast of Colombia west of 75w and within 120 nm along the coast of west Panama west of 80w. This is leaving the remainder of the basin with fair weather tonight. Fresh to strong northeast trade winds will affect the northwest coast of Colombia tonight. The special features low and tropical wave will track northwest and pass near the Virgin Islands tonight, then north of Puerto Rico on Wednesday, and north of Hispaniola Thursday.

Weather Underground Caribbean Forecast

The tropics will stay active in the eastern Pacific and the Atlantic Basin on Thursday. Tropical Storm Gaston is located 475 nautical miles west of the southernmost Cabo Verde Islands, with maximum wind speeds at 50 mph (45 kts). The forecast track for Gaston takes this system northwestward over the central Atlantic. By Thursday, Gaston is expected to be upgraded to a category 1 hurricane, with wind speeds ranging between 74 to 95 mph (64 to 82 kts). This system does not pose threats to any major land masses. A tropical wave is located a couple hundred nautical miles east of the Leeward Islands. This wave of low pressure has a medium, 50% chance to develop into a tropical cyclone as it pushes west northwestward over the northern Leeward Islands and the Greater Antilles. Regardless of development, heavy rain and gusty winds will impact the region. In the eastern Pacific, Tropical Depression Kay is situated 565 nautical miles west of the southern tip of Baja California, with maximum wind speeds at 35 mph (30 kts). The forecast track for Kay takes this system westward. Kay will likely deteriorate over the next 24 to 48 hours. A broad area of low pressure is located 347 nautical miles south southwest of Acapulco, Mexico. This system has a medium, 50% chance to develop into a tropical cyclone as it shifts westward. A cluster of showers and thunderstorms is located 870 nautical miles south southwest of the southern tip of Baja California. This cluster of storms has a low, 30% chance to form into a tropical cyclone as it moves west northwestward.


48 Hour Forecast – Favorable Environmental Conditions For Tropical Development



Infrared Satellite in Belize City

Tropical Storm Gaston; Disturbance east of Lesser Antilles possible threat to Bahamas and Florida late this weekend, early next week
Accuweather

8/24/2016 6:36:32 AM

Tropical Storm Gaston is located at Tropical Storm Gaston with maximum sustained winds of 70 mph and gusts to 85 mph, moving WNW at 17 mph, pressure 29.50 in / 998 mb

Tropical Storm Gaston is currently moving west-northwestward at a brisk pace away from the Cabo Verde Islands. Conditions will be favorable for steady strengthening over the next 24-36 hours and it will likely strengthen into a hurricane Wednesday. Later this week, strong upper-level winds causing shear may limit further strengthening of Gaston while it tracks to the northwest into the open waters of the central Atlantic. Long range computer models show the wind shear lessening over the weekend and it is possible that Gaston strengthens even further over the open waters of the central Atlantic.

Elsewhere, a strong tropical wave located near Guadeloupe has a broad circulation that is oriented from northwest to southeast. On Tuesday, hurricane hunter aircraft detected the lowest pressure farther south along the wave so it will be important to locate a center of circulation before models can latch onto more dependable track forecasts. Favorable environmental conditions in the path of this system will allow for slow strengthening across the northern Leeward Islands over the next 24 hours and from there it depends on where a low level center may track. A path north of the Greater Antilles into the Bahamas favors a better chance of a stronger system affecting the Bahamas over the weekend and perhaps southern Florida late this weekend or early next week. A farther south path favors a lower chance of a stronger system due to interaction with Puerto Rico and Hispaniola. Residents of these islands as well as those in Florida will want to keep a close watch on the progress of this system.

This tropical system will bring gusty winds, heavy rain, possible flooding to the northern Lesser Antilles into Wednesday morning before impacting the Virgin Islands and possibly Puerto Rico later Wednesday and Wednesday night.



120 Hour Forecast – Favorable Environmental Conditions For Tropical Development

Invest 99-L Is Expected To Become Tropical Storm Hermine Either Later Today Or On Thursday; This System Poses A Potential Very Serious Threat To The Bahamas, South Florida & The Florida Keys This Weekend & Especially To The US Gulf Coast Early Next Week
Rob Lightbown of Crown Weather Services

August 24, 2016

Invest 99-L Located Over The Northern Lesser Antilles: Invest 99-L has become more organized during the overnight hours and it appears that it is either close to, if not already a tropical depression or a tropical storm. Reconnaissance aircraft is scheduled to investigate Invest 99-L again to determine whether it is now either a tropical depression or a tropical storm. Invest 99-L is currently producing very heavy rainfall across the islands of Guadeloupe and Antigua and this heavy rainfall is expected to continue through this morning. This heavy rainfall is expected to spread into the Virgin Islands and Puerto Rico by this afternoon and then continue into tonight. If you are in the central and northern Lesser Antilles, Virgin Islands and Puerto Rico, please be aware that flash flooding and mudslides could be a problem due to this heavy rainfall.

Once Invest 99-L tracks to the north of Hispaniola and into the vicinity of the Turks and Caicos Islands on Thursday, it is expected to move into an environment that is increasingly more favorable for development and intensification. These increasing more favorable conditions will consist of decreasing wind shear, extremely warm ocean water temperatures and a very moist environment.

This system needs to be watched extremely closely when it tracks across the eastern and northern Bahamas on Friday and Saturday as it could really strengthen into a hurricane as it turns westward towards south Florida and the Florida Keys. Everyone across the Bahamas, in south Florida & the Florida Keys should closely monitor the progress of Invest 99-L.

Beyond this, I have considerable amount of concern about a serious hurricane threat to some part of the US Gulf Coast early next week. At this point, the highest area of concern is from Houston-Galveston, Texas eastward to Apalachicola, Florida. I strongly urge everyone along the US Gulf Coast to closely monitor the progress of this system.

Looking at the latest model guidance – it appears that the GFS continues to be “out to lunch” and is missing the mark by a long shot. It makes no sense to me as to why the GFS model is not forecasting the intensification of this system when it is, at the same, forecasting a favorable environment for strengthening when it’s in the Bahamas and in the eastern Gulf of Mexico. Based on this, the GFS model guidance will be disregarded again this morning.

The European model guidance continues to be locked in and very consistent in forecasting that Invest 99-L will strengthen quickly into a borderline tropical storm/hurricane as it tracks westward from the northern Bahamas to southeast Florida on Saturday and Saturday night. From there, the European model guidance has shifted westward with its track in the Gulf of Mexico and now shows a strengthening hurricane that tracks from east to west across the Gulf of Mexico on Sunday, Monday and Tuesday. The European model guidance now forecasts this system to make landfall near the Texas-Louisiana border as a powerful hurricane on Wednesday evening. It needs to be pointed out that this is the fourth forecast run in a row that shows a Gulf of Mexico hurricane by the European model guidance and this is concerning.

The European ensemble guidance track spread when Invest 99-L moves into the Gulf of Mexico ranges from a due west track towards south Texas and northeast Mexico all the way to a northward turn into the Florida Panhandle. It should be noted that a majority of ensemble members are clustered from southeast Texas to the Mississippi and Alabama coast. It should be noted that 33 out of the 51 European ensemble members forecast this to be a strong tropical cyclone in the Gulf of Mexico.

In addition to this, the UKMET and HWRF models, which are both reliable model guidance members, continues to be relatively consistent in forecasting that Invest 99-L will be either a tropical storm or a hurricane when it crosses south Florida this weekend & then intensifies it into a significant hurricane as it pushes west-northwest across the Gulf of Mexico towards the Texas-Louisiana border on Wednesday or Thursday.

Here Are My Thoughts: It looks fairly likely that Invest 99-L will move to the west-northwest reaching the southeastern Bahamas by late Thursday and reaching the area around Nassau and Andros Island sometime on Saturday. The reason why it is expected to move on a west-northwest course is that an area of high pressure is expected to push to the northeast and open up a space for Invest 99-L to head towards the Bahamas and south Florida.

It looks likely that Invest 99-L will slowly develop over the next couple days as environmental conditions are not conducive to development and intensification. With that said, it would not surprise me to find out that Invest 99-L is actually a tropical depression given the presentation on satellite imagery. The more rapid and significant development and strengthening is likely to wait until Friday and especially this weekend.

Beyond this, I am very concerned and worried that this system will be a hurricane for south Florida and the Florida Keys and then a significant hurricane for some part of the US Gulf Coast. The environmental conditions are forecast to be quite favorable for intensification in the northern Bahamas. These favorable environmental conditions are forecast to consist of ocean water temperatures in the mid and upper 80s, low wind shear and a potentially moist environment.

The upper level pattern for this weekend into next week is expected to consist of a large upper level ridge of high pressure over the US Mid-Atlantic States and this will cause this system to be steered westward from the Bahamas into south Florida this weekend and then into the Gulf of Mexico early next week. The actual strength and position of the upper level ridge of high pressure will be crucial in determining how far west this system tracks before it turns northwestward and northward. A stronger upper level ridge could cause this system to track the entire distance of the Gulf of Mexico towards a landfall along the lower or middle Texas coast. Meanwhile, a slightly weaker and more eastward positioned upper level ridge could lead to this system turning northward towards the US northern Gulf Coast between Louisiana and Alabama.

Now, I am trying my best not to scare or alarm you, but I do need you to be aware that this system has the potential to be a tropical storm or a hurricane for the northern Bahamas, a hurricane for south Florida and the Florida Keys and then a potentially serious hurricane for some part of the US Gulf Coast. At this point, it would be a very good idea to go through your hurricane evacuation plans, your hurricane preparedness information and your hurricane preparedness kit to make sure you have what you need and you know what to do, just in case.

So, bottom line is that I strongly urge everyone in the Bahamas, south Florida, the Florida Keys and the entire US Gulf Coast to pay very close attention to the progress and forecasts of Invest 99-L.

An Update On Invest 99-L will be posted sometime between 5 and 8 pm ET/4 and 7 pm CT today, especially if reconnaissance aircraft find a tropical depression or tropical storm this afternoon.


Invest 99L Information:


Model Track Forecast:

Courtesy of Weather Underground
Courtesy of Weather Underground
Courtesy of Weather Underground

Model Intensity Forecast:
Courtesy of Weather Underground

Satellite Imagery:






Theat to Southeast U.S. Growing From 99L; Gaston Forms in Eastern Atlantic
Jeff Masters

August 23, 2016

The Hurricane Hunters are in the air, investigating Invest 99L, a steadily organizing tropical wave that was located about 300 miles east of the northern Lesser Antilles late Tuesday morning. This storm will bring heavy rains and gusty winds to the northern Lesser Antilles Islands Tuesday evening through Wednesday, and is likely to develop into a tropical storm or hurricane that will affect the Bahamas and the Southeast U.S. coast late this week or early next week.

Satellite loops on Tuesday morning showed that heavy thunderstorm activity associated with 99L had slowly increased over the the previous 24 hours. The storm was still poorly organized, though, with no surface circulation center apparent and few low-level spiral bands. Upper-level cirrus clouds streaming away from the northeast side of the storm gave evidence that an upper-level outflow channel was trying to develop, however. Dry air from the Saharan Air Layer (SAL) that has been interfering with development over the past few days had decreased, as seen on water vapor satellite imagery. Wind shear was marginally favorable for development, at 10 - 15 knots, and sea surface temperatures (SSTs) were favorable for development: 28.5 - 29°C (83 - 84°F) (about 0.5°C above average.)


Figure 1. Latest satellite image of 99L.

Track forecast: 99L likely to affect the Bahamas and Southeast U.S.
A strong ridge of high pressure will keep 99L headed west-northwest over the next few days, and the storm will traverse the northern Lesser Antilles Tuesday night through Wednesday, track close to or just north of Puerto Rico on Wednesday night, then reach the Southeastern Bahamas by Thursday. At this time, the models keep 99L far enough north of the island of Hispaniola to prevent the high mountains there from significantly disrupting 99L. However, we cannot have confidence in this forecast until 99L develops a well-defined center that the models can track. Due to its large size, 99L will be capable of bringing torrential rains and flash flooding and mudslides to the Dominican Republic and Haiti. The uncertainty about the track increases greatly on Friday and into the weekend, due to a potential weakness in the ridge of high pressure steering the storm caused by a trough of low pressure passing to the north of 99L. The storm should slow its forward motion to 5 - 10 mph Friday through Saturday, in response to this trough, and may turn to the northwest or north near the central Bahamas. Over 80% of the ensemble members from the 00Z Tuesday runs of the European and GFS models show 99L hitting the Southeast U.S. between Florida and South Carolina sometime Sunday or later; very few show the storm missing the U.S. entirely. The track and intensity of 99L may be affected by the remnants of Tropical Storm Fiona, which NHC stopped issuing advisories on at 11 am EDT Tuesday. The remains of Fiona will be a few hundred miles to the north or northeast of 99L this weekend. Hurricane Gaston will be too far from 99L to exert a steering influence on it.


Figure 2. The 00Z Tuesday morning run of the operational European model (run at high resolution, shown in red) and its ensemble members (50 runs with slightly different initial conditions done at lower resolution, shown in black) came up with a variety of solutions for the future track and intensity of 99L. The operational model run—which is usually the best forecast, since the model runs at the highest resolution with the proper initial conditions—showed a track for 99L across Florida and into the Gulf of Mexico, with the storm peaking as a Category 1 hurricane. The track and intensity forecasts of the four members of the European ensemble that have done the best job tracking the progress of 99L over the previous 24 hours (called the “high probability cluster”) are also plotted here. They show that a more northeasterly track may be likely. Note that while the European model is our best model for predicting hurricane tracks, it does a poor job forecasting intensity and is generally disregarded by NHC for making intensity forecasts. Image taken from a custom software package used by Weather Underground.

Intensity forecast for 99L: a potentially dangerous storm for the Southeast U.S.
Heavy rains from 99L will likely cause flash flooding problems in the Lesser Antilles, Virgin Islands, and Puerto Rico. Wind damage should not be an issue, since 99L will likely be, at worst, a moderate-strength tropical storm with 55 mph winds once it leaves the islands. The 8 am EDT Tuesday run of the SHIPS model showed moderately favorable conditions for development through Friday. Wind shear will be in the light to moderate range, 5 - 15 knots, and SSTs will increase from 28.5°C (83°F) to 30°C (86°F), accompanied by an increase in the total heat content of the ocean. Working against development of 99L will be the large size of the storm, dry air of the SAL, and large-scale sinking air over the tropical Atlantic imparted by an unfavorable phase of the Madden-Julian Oscillation (MJO). Two of the Tuesday morning (00Z) operational runs of our three reliable models for predicting tropical cyclone genesis--the European, and UKMET models--showed development of 99L into a tropical storm over the next five days. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave 99L 2-day and 5-day development odds of 50% and 60%, respectively. I think the 5-day odds should be higher, at 70%.

This storm has the potential to be a dangerous one for the Bahamas and the Southeast United States. The models are predicting a favorable environment for development near the Bahamas, and the storm will be moving quite slowly during its closest approach to the islands, potentially allowing for some very high rainfall totals in the Bahamas. While the 00Z Tuesday run of the GFS model did not show development of 99L into a tropical depression, the European model ensemble forecast had 1/3 of its members predicting that 99L would eventually become a hurricane. The storm will likely spend 2 - 3 days over a region of ocean with SSTs that are near record-warm: 29 - 30°C (84 - 86°F). Warm waters extend to great depth, resulting in an unusually high total ocean heat content. With some models forecasting that wind shear will be in the light to moderate range at this time, we have the potential for 99L--which has a large circulation--to rapidly intensify into a large major hurricane that will hit the Southeast U.S. coast on Sunday or Monday. The uncertainties are high, and we will have to wait for the storm to develop into a tropical depression before we can have more confidence in what the models are saying.

Gaston forms in the Eastern Atlantic
Tropical Storm Gaston, the seventh named storm of the 2016 Atlantic hurricane season, formed early Wednesday morning in the eastern Atlantic, a few hundred miles west of the Cabo Verde Islands. Gaston’s formation date of August 23 comes more than three weeks earlier than the usual September 16 formation date of the season’s seventh storm. Gaston is headed northwestwards into a area of ocean where it is highly unlikely to be a threat to any land areas.


99L Becoming More Likely to Develop Near the Bahamas in a Few Days



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


Tropical Atlantic Wide Visible Satellite Image





Edited by Marty (Yesterday at 06:18 AM)