Belize Tropical Weather Outlook: September 24, 2016

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Area wind information

Belize NMS Forecast

6:00 AM in Belize, September 24, 2016

At 3am Tropical Storm Karl was located near 31.7N latitude, 64.3W longitude or about 50 miles southeast of Bermuda. Karl was moving to the northeast at 17mph with maximum sustained winds of 65mph.

At 3am Tropical Depression Lisa was located near latitude 23.8N and longitude 37.9W or about 1050 miles west-northwest of the Cape Verde Islands. Lisa was moving to the northwest at 9 mph with maximum sustained winds of 35mph.

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 24, 2016

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

The National Hurricane Center is issuing advisories on Tropical Storm Karl, located east of Bermuda, and on Tropical Depression Lisa, located over the eastern tropical Atlantic.

A tropical wave, accompanied by a broad area of low pressure, is located south of the Cabo Verde islands. This disturbance is expected to move rapidly westward across the tropical Atlantic Ocean at 20 to 25 mph for the next several days. Environmental conditions are expected to become conducive for gradual development, and a tropical depression could form while the system approaches the Lesser Antilles and moves into the Caribbean Sea by the middle of next week.
* Formation chance through 48 hours...low...10 percent
* formation chance through 5 days...medium...50 percent

Tropical Weather Discussion

...Special features...
Tropical Storm Karl is centered near 31.7n 64.3w at 24/0900 UTC or about 43 nm southeast of Bermuda moving north-northeast at 15 kt. Estimated minimum central pressure is 994 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate convection extends north of 29n between 60w-67w. Please see the latest NHC public intermediate advisory under AWIPS/WMO headers miatcpat2/wtnt32 knhc and NHC forecast/advisory under AWIPS/WMO headers miatcmat2/wtnt22 knhc for more details.

Tropical Depression Lisa is centered near 23.8n 37.9w at 24/0900 UTC or about 912 nm west-northwest of the Cabo Verde islands northwest at 8 kt. Estimated minimum central pressure is 1010 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. An area of moderate convection has developed to the north of the system's center extending from 24n-27n between 33w-37w. Please see the latest NHC forecast/advisory under AWIPS/WMO headers miatcmat3/wtnt23 knhc for more details.

...Tropical waves...
A tropical wave is moving across the eastern Atlantic with axis extending from 15n23w to 04n23w, moving west near 10 kt over the past 24 hours. The wave coincides with a 700 mb trough depicted by global guidance and is embedded within a surge of moisture as seen on the total perceptible water imagery. Cloudiness and isolated showers are observed in the wave's environment between 00n-13n.

A tropical wave is in the central tropical Atlantic with axis that extends from 20n53w to 11n53w, moving west near 15 kt over the past 24 hours. This wave position coincides with a 700 mb trough noted in global models and is embedded within a surge of moisture as seen on the total perceptible water imagery. Scattered moderate convection prevails along the northern portion of the wave, mainly north of 17n between 50w-55w.

A tropical wave extends across the southern portion of the Bay of Campeche into the epac with axis from 19n95w to 10n96w, moving west near 15 kt over the past 24 hours. This wave is embedded within an area of moisture as seen on the total perceptible water imagery. Scattered moderate convection prevails in the wave's environment south of 20n between 90w-102w.

Caribbean Sea...

A low-level trough continues to enhancing convection across the western Caribbean west of 82w affecting portions of Honduras, Belize and the Yucatan Peninsula. Scattered moderate convection is observed south of 12n due to the monsoon trough that extends along 09n between 76w-84w. No significant convection is observed over the remainder of the basin at this time as a surface ridge extends over the area anchored over the eastern Atlantic. Scatterometer data depicts moderate to fresh trades across the area except south of 14n between 69w-73w where fresh to strong winds prevail. Expect a similar weather pattern to continue through the next 24 hours. A tropical wave will approach from the east enhancing convection over the Lesser Antilles, Virgin Islands and Puerto Rico by the end of the weekend.

Weather Underground Caribbean Forecast

Tropical cyclone development is anticipated across the eastern Pacific and the Atlantic Basin on Sunday. In the Atlantic Basin, Tropical Storm Karl is located about 252 nautical miles south of Bermuda. Karl was re upgraded to a tropical storm over the past 24 hours, with maximum wind speeds at 60 mph (50 kts). The forecast track for Tropical Storm Karl takes this system north northeastward over the western Atlantic. Karl is expected to brush across the southeast coast of Bermuda throughout early Saturday morning. Heavy rain and dangerous storm surge will impact the island. By Sunday, this system will accelerate northeastward, and will likely be upgraded to a category 1 hurricane. Wind speeds are forecast to range between 74 to 95 mph (64 to 82 kts). Tropical Storm Lisa is located roughly 747 nautical miles west northwest of the Cabo Verde Islands, with maximum wind speeds at 40 mph (35 kts). The forecast track for Lisa takes this system northwestward over the eastern Atlantic. By Sunday, Lisa is expected to be downgraded to a tropical depression, with wind speeds dropping below 39 mph (33 kts). A tropical wave is located about 300 nautical miles southeast of the Cabo Verde Islands. This system has a low, nearly 0% chance to develop into a tropical cyclone. In the eastern Pacific, an area of low pressure is located approximately 686 nautical miles south southwest of the southern tip of Baja California. This system has a high, 70% chance to develop into a tropical cyclone as it moves northwestward.

48 Hour Forecast – Favorable Environmental Conditions For Tropical Development

Infrared Satellite in Belize City

Tropical Storm conditions continue across Bermuda Saturday morning; Lisa not a threat to land

9/24/2016 4:20:19 AM

Tropical Depression Lisa is located at 23.8° N, -37.9° W with maximum sustained winds of 35 mph and gusts to 45 mph, moving NW 9 mph, pressure 29.83 in / 1010 mb.

Tropical Storm Karl is located at 31.7° N, -64.3° W with maximum sustained winds of 65 mph and gusts to 75 mph, moving NE 17 mph, pressure 29.36 in / 994 mb.

Tropical Storm Karl continues to approach Bermuda from the south early this morning. As of 4 a.m. EDT, observed wind gusts are past 40 mph over parts of the islands. Rainfall amounts as of 4 a.m. EDT are averaging about 0.75 of an inch across Bermuda. Expect Karl to strengthen early this morning, perhaps into a Category 1 hurricane just to the east of Bermuda. Latest track takes Karl just to the southeast of the island, which will minimize any significant impacts. However, due to the close track of the storm, conditions will continue to deteriorate through midmorning.

Expect Karl to make a very close pass to the south and east of Bermuda by 40 to 80 miles. This will place Bermuda on the northern and western quadrant of the system. Tropical storm-force winds of 40-60 mph with higher gusts to 80 mph, especially across elevated/exposed locations are expected during the morning hours. Latest radar imagery continues to show heavy rain bands impacting the island which is forecast to continue through this morning. This will lead to localized flooding with rain totals exceeding 4 to 6 inches, with isolated 8 inches possible. Large, battering waves can lead to some beach erosion and there can be some minor coastal flooding.

Karl will accelerate northeastward away from Bermuda later today. All heavy rain and high winds in association with the storm will diminish. However, rough surf will continue through the evening and nighttime hours with gusty northwesterly winds.

Eventually, Karl will become a powerful non-tropical storm system over the North Atlantic. It will threaten the U.K. and Ireland with damaging winds on Tuesday and Tuesday night of the coming week.

Elsewhere in the Atlantic Basin, Lisa has weakened into a tropical depression in the open waters of the Atlantic. Lisa will continue to fight intense wind shear and endure cooler sea-surface temperatures with no further strengthening expected in the short term.

There are no other areas of concern for tropical development across the basin in the short range, but we are watching a tropical wave that is located just off the African Coast. This has concern for long-range development near the Caribbean towards the end of next week.

120 Hour Forecast – Favorable Environmental Conditions For Tropical Development

Tropical Disturbance In The Eastern Atlantic Has The Potential To Be A Tropical Storm As It Approaches Barbados & The Lesser Antilles On Wednesday & Then Could Be A Caribbean Hurricane Threat Next Weekend
Rob Lightbown of Crown Weather Services

September 24, 2016

Tropical Disturbance In The Eastern Atlantic Has The Potential To Be A Tropical Storm As It Approaches Barbados & The Lesser Antilles On Wednesday & Then Could Be A Caribbean Hurricane Threat Next Weekend: Karl passed within about 60 miles of Bermuda late last night and early this morning bringing tropical storm conditions to the island. Karl is now moving away from Bermuda and will push northeastward into the open Atlantic over the next few days. The winds, rain and rough seas are forecast to subside throughout the rest of today and Sunday is likely to be a nice day across Bermuda.

So, we say goodbye to Karl and now focus on a tropical disturbance that is currently located in the eastern Atlantic. This particular tropical disturbance has the potential to become a really big problem when it moves into the Caribbean late next week and next weekend.

Current satellite imagery indicates that this tropical disturbance is producing some thunderstorm activity with some subtle signs of organization in the satellite presentation. Right now, the only impediment to development over the next couple of days is some 20 knots of southeasterly wind shear. This wind shear is forecast to decrease to 10 knots or less once this disturbance reaches 40 West Longitude by Sunday night and Monday. Other than this wind shear, the other environmental conditions, including moisture and sea surface temperatures, are favorable for development. This means that I think we will see this disturbance develop into a tropical depression perhaps as soon as Monday or Tuesday and possibly be a tropical storm when it reaches Barbados and the Lesser Antilles on Wednesday.

For Those Of You In Barbados & The Lesser Antilles: I do have concerns regarding the impact this system could have on Barbados and the Lesser Antilles, especially the southern Lesser Antilles. Everyone across Barbados, the Lesser Antilles and the entire eastern Caribbean should pay extremely close attention to the progress of this disturbance as I think there is a very good chance that it will impact you with tropical storm conditions starting on late Tuesday night and Wednesday morning and continuing through all of Wednesday, all of Wednesday night and part of Thursday. Heavy flooding rainfall, strong winds with gusts of up to 60 mph and very rough seas will all be a threat.

Beyond this, all 3 major global models (GFS, European & Canadian) are forecasting that this system may become a hurricane in the northwestern Caribbean by late next weekend. At the same time, these models are also forecasting that a significant trough of low pressure over the central United States could steer this system into the Gulf of Mexico. Many things are likely to change with these models, but the fact is that these models are forecasting the potential for a hurricane threat in the western and northwestern Caribbean and possibly the Gulf of Mexico in 7 to 9 days from now. These model trends are quite concerning & something to watch closely.

The ensemble guidance agrees with their operational counterparts in forecasting a tropical system to be located in the eastern Caribbean by late next week and early next weekend. From there, the ensemble guidance members diverge with some members forecasting a turn to the north across the Bahamas and up the US East Coast during the October 3rd to October 7th time frame. Other ensemble members forecast a track across Jamaica and into the northwestern Caribbean next Sunday and next Monday followed by a track into the eastern Gulf of Mexico towards the US northern Gulf Coast between October 5th and October 8th. This says to me that the model guidance are in good agreement on a track into the eastern Caribbean late next week. From there, however, the uncertainty on where this system tracks increases significantly and it is a disturbance to keep an eye on if you live anywhere from the Caribbean through the Gulf of Mexico, including the entire US Gulf Coast, through the Florida Peninsula up the US East Coast. I know it is a very large uncertainty area, but we are talking about a 10 day to 2 week forecast and these types of forecasts do have a large amount of uncertainty.

Here Are My Thoughts: As I have already mentioned, I urge everyone in Barbados and the Lesser Antilles to keep a very close eye on the progress of this tropical disturbance. Be ready for tropical storm conditions, including heavy flooding rainfall, wind gusts of up to 60 mph and very rough seas, from late Tuesday night through Wednesday, Wednesday night and part of Thursday.

When looking at the current weather data and the model data, there are some things that do jump out at me. The first is that there is 25 to 40 knots of west-northwesterly wind shear occurring from the southern Gulf of Mexico through the entire Caribbean. If these strong wind shear values continue and do not decrease like the models are forecasting, then any tropical system moving across the Caribbean late next week, next weekend and beyond will likely weaken and dissipate due to these unfavorable environmental conditions.

The second item that jumps out at me is the overwhelming model guidance consistency in forecasting a very strong hurricane in the western Caribbean. This operational model consistency has the full support of both the GFS ensemble and European ensemble guidance. One thing I did notice is that the model guidance are forecasting that this disturbance may create its own environment building a shield of sorts against unfavorable wind shear by the time it reaches the eastern Atlantic next weekend. I’m not sure if I quite buy this at this point, but it is something to keep in mind and is a reason why all of the models are forecasting this system to become such a strong storm by the time it reaches the western and northwestern Caribbean late next weekend and early the following week (October 2nd-3rd).

The third item to mention is that right now the Madden Julian Oscillation is in an unfavorable phase for development across the Atlantic Basin. This is why Julia, Karl and Lisa have all struggled to develop and strengthen. This is forecast to change as soon as from next weekend through the week of October 3rd to October 7th as the Madden Julian Oscillation is forecast to switch into a favorable mode across the Caribbean, Gulf of Mexico and the western Atlantic. This favorable phase lends support to the idea of a Caribbean tropical cyclone next weekend and beyond.

So, this means I am cautiously concerned with the potential for a tropical storm or a hurricane in the Caribbean by late next weekend and early the following week. I use the word cautiously concerned because I do indications that do support the idea of a hurricane in the central, western and northwestern Caribbean. On the other hand, I do see reasons why we could see little or no development of any system that moves into the Caribbean next weekend. So, at this point I think for now everyone in the Caribbean should just keep a close eye on this tropical disturbance and look through your hurricane preparedness kits over the next few days to make sure you have everything stocked up. Don’t buy into any one model forecast as all of them will change over the next several days, but be aware that there is the possibility of a strengthening tropical storm or even a hurricane in the Caribbean by the end of next week through next weekend and beyond.

Bottom line is that we are going to be monitoring this tropical disturbance very closely in the coming days to see how develops as it pushes westward. Those of you in the Lesser Antilles and Barbados should especially keep a close eye on this system as it looks increasingly more likely that it may bring tropical storm conditions to you from late Tuesday night through Wednesday, Wednesday night and part of Thursday.

Karl Approaches Bermuda; Trouble in the Caribbean Next Week?
Jeff Masters

September 23, 2016

After nearly a week as a lackluster system, Tropical Storm Karl is finally gaining strength as it heads toward a close encounter with Bermuda. As of the 11 am EDT advisory, Karl was located about 250 miles south of Bermuda, moving north at 12 mph. Karl’s top sustained winds were holding at 60 mph, its peak intensity thus far. Karl is continuing its multi-day struggle with vertical wind shear that’s tended to push its showers and thunderstorms (convection) east of its center. On Thursday night, the storm managed to consolidate a healthy core of convection around its center, but Karl remains somewhat asymmetric, with a comma-shaped structure and a large band of convection well to its east.

Figure 1. Latest satellite image for Tropical Storm Karl.

Outlook for Karl
A Hurricane Watch and Tropical Storm Warning are now in effect for Bermuda, and it is not out of the question that Karl will pass near the island as a minimal hurricane. Karl’s motion slowed dramatically on Thursday as the storm began rounding the west edge of a large subtropical upper-level high. The overall track forecast is straightforward: Karl will move north on Friday and begin arcing toward the north-northeast by early Saturday, bringing it near Bermuda by midday Saturday. Karl will then rapidly accelerate northeastward through the rest of the weekend and into early next week. The longitude of Karl’s center on Friday morning was only a few miles west of Hamilton, Bermuda, so it would be difficult for Karl’s center to pass directly over the island if it were to gain any eastward component to its motion as it approaches Bermuda. The 06Z Friday run of the HWRF model is a western outlier, bringing the center of Karl very close to the island on Saturday morning. The 06Z Friday GFS run is somewhat faster and keeps Karl about 50-100 miles southeast of Bermuda, as do the 00Z Friday runs of the UKMET and European models.

Figure 2. WU depiction of National Hurricane Center forecast for Tropical Storm Karl issued Friday morning, September 23, 2016. Bermuda is depicted as the tiny dot just north of the “8 PM Fri” label.

Models agree that Karl’s strength will peak later in the weekend, when it begins to merge with a midlatitude storm system over the North Atlantic while racing northeastward. Karl will most likely be strengthening on Friday night into early Saturday as it nears Bermuda, and NHC takes Karl to minimal hurricane strength by 12Z (8:00 am EDT) Saturday. The worst-case scenario would be for Karl to approach or reach minimal hurricane strength and pass very near Bermuda. The island has experienced many hurricanes over the years and is well equipped to handle a storm of that strength. A more likely scenario, and the one favored by NHC, is that Karl will pass about 50 to 100 miles southeast of Bermuda, keeping the island on the weaker left-hand side of the storm. That would still be close enough to bring tropical storm-force conditions, so Bermuda could experience a brief period late tonight or early Saturday with sustained winds of 40 - 60 mph, including higher gusts, along with very heavy rain that could total 3” - 5”. The island will also be buffeted by high surf and large swells. Karl’s accelerating motion will limit the main period of impact to just a few hours. Karl was already bringing heavy rain showers to Bermuda on Friday morning, as seen on Bermuda radar.

An African tropical wave that could be trouble
A  tropical wave located a few hundred miles west of the coast of Africa and about 350 miles southeast of the Cabo Verde Islands on Friday morning was poorly organized, with only a limited amount of heavy thunderstorm activity and spin. This wave is currently too close to the equator (near 8°N) to be able to leverage the Earth’s spin and acquire enough spin of its own to develop into a tropical depression, and is not likely to develop through this weekend as it heads rapidly west at 20 - 25 mph. However, the tropical wave may move far enough from the equator to be able to develop by early next week, when it reaches a point about halfway between the Lesser Antilles Islands and the coast of Africa. There was increased model support for development of this tropical wave in the Friday morning runs of the models compared to their Thursday morning runs. Our top three models for predicting hurricane genesis—the GFS, UKMET and European models—all predicted in their 00Z Friday runs that this tropical wave would develop into a tropical depression or tropical storm between Monday and Thursday next week. About 60% of the 20 forecasts from the members of the 00Z Friday GFS ensemble showed development, and about 30% of the 50 members of the European model ensemble did so. Troublingly, a considerable number of the ensemble model runs showed this storm becoming a hurricane in the Caribbean. Working against development, at least in the next five days, will be the fast forward speed of the system—tropical waves moving at 20 mph or faster usually have trouble getting organized. However, the storm does not have as much dry air to contend with compared to other storms we have seen this year, and it would not be a surprise to see this system be close to tropical depression or tropical storm status when it begins moving into the Lesser Antilles Islands on Tuesday night.  In their 8 am EDT Friday Tropical Weather Outlook, NHC gave this system 2-day and 5-day development odds of 0% and 20%, respectively.

Figure 3. Forecasts out to ten days from the 00Z Friday European model ensemble (top) and GFS model ensemble (bottom) had a number of their 70 members predicting a hurricane for late next week in the Caribbean (light blue dots.) The operational versions of the models, run at higher resolution (red lines), also showed the storm becoming a hurricane by ten days into the future.

Tail-end development in the Gulf of Mexico looks unlikely
A cold front will move into Texas on Monday, and potentially stall just offshore of Texas on Tuesday. We’ll need to watch the tail end of this cold front for tropical development if it lingers over the Gulf of Mexico for a few days. However, there is less model support today than yesterday for this occurring, with fewer than 5% of the members of the 00Z Friday GFS and European model ensemble forecasts showing potential tropical development over the Gulf of Mexico next week.

Sept. 23: Karl Strengthening – Impacts to Bermuda Friday Night and Saturday Morning

Tropical Storm Karl has begun to strengthen this morning, as the storm’s circulation has now become more aligned with its convection. It may not take long for Karl to approach hurricane strength now that intensification has begun. A tropical storm warning is in effect for Bermuda, and hurricane conditions could be possible if Karl continues strengthening and passes close enough to the island early Saturday morning. At the moment, Karl is expected to pass about 100 km southeast of Bermuda, but even small changes in its track could bring it closer. Tropical Storm conditions are expected to reach the island sometime tonight.

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Tropical Atlantic Wide Visible Satellite Image

Edited by Marty (Yesterday at 09:17 AM)