Belize Tropical Weather Outlook: September 23, 2018

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Area wind information


Belize NMS Forecast

September 23, 2018

AT 3 AM: Tropical Storm Kirk was centered near latitude 9.1 North, longitude 28.0 West. Kirk was moving W at 18 mph with maximum sustained windsof 40 mph. The center of Tropical Depression Eleven was located near latitude 14.5 North, longitude 55.0 West. The depression was moving toward the NW at 6 mph and maximum sustained winds are near 30 mph. NO THREAT TO BELIZE AT THIS TIME. Elsewhere, tropical cyclone formation is not expected during the next 48 hours.

USA National Weather Service Forecast

September 23, 2018

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

The National Hurricane Center is issuing advisories on Tropical Depression Eleven, located several hundred miles east of the Windward Islands, and on Tropical Storm Kirk, located several hundred miles south-southwest of the Cabo Verde Islands.

A broad area of low pressure located about 300 miles south-southwest of Bermuda continues to produce limited shower and thunderstorm activity. Although strong upper-level winds currently affecting the system are expected to diminish later today and could allow for some development during the next couple of days, the low will continue to be embedded in a very dry environment while it moves westward and west-northwestward at about 10 mph over the southwestern Atlantic Ocean. By Tuesday or Wednesday, upper-level winds are forecast to strengthen again, likely limiting additional development as the system turns northward and moves by the southeastern coast of the United States.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...30 percent.

The evolution of a complex weather system over the central Atlantic Ocean could lead to two separate episodes of subtropical or tropical development during the upcoming week. First, a non-tropical low pressure system currently located about 1000 miles west-southwest of the Azores is producing gale-force winds with some associated showers and thunderstorms. Conditions appear conducive for this system to acquire some subtropical or tropical characteristics during the next day or so while meandering over the central Atlantic Ocean, and the low could become a subtropical or tropical cyclone before it is overtaken and absorbed by a cold front late Tuesday or Wednesday. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...medium...60 percent.

A second non-tropical low pressure system is expected to form along the central Atlantic cold front by Wednesday several hundred miles west of the Azores. Conditions appear conducive for this system to also acquire subtropical or tropical characteristics by the latter part of this week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

Tropical Weather Discussion

...Special features...

Tropical Storm Kirk centered near 9.0N 26.4W at 23/0300 UTC, or 370 nm SSW of the Southernmost Cabo Verde Islands, moving WNW at 14 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Some strengthening is forecast through Sunday, with little change in intensity expected on Monday and Tuesday. Scattered moderate to strong convection is observed from 08N-11N between 24W-31W. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT2/WTNT32 KNHC for more details.

Tropical Depression Eleven centered near 13.8N 54.5W at 23/0300 UTC, or 380 nm E of the Windward Islands, moving NW at 3 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 25 kt with gusts to 35 kt. The depression is expected to weaken to a remnant low on Sunday and dissipate by Sunday night east of the Lesser Antilles. Scattered moderate convection is noted from 12N-15N between 51W-55W. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC for more details.

Satellite imagery indicates that a frontal non-tropical low pressure system is located about 1000 nm west-southwest of the Azores. Conditions are expected to become conducive for this low to acquire subtropical or tropical characteristics during the next day or so, and a subtropical or tropical cyclone is likely to form by early next week while the low meanders over the central Atlantic Ocean. The system has a medium chance of tropical cyclone formation within the next 48 hours. Please refer to the latest Tropical Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more information.

A cold front extends from a 1004 mb low pressure located N of the area near 34N44W to 31N41W to 25N50W to 28N59W. The most recent scatterometer data provide observations of minimal gale-force winds N of 29N and within 60 nm south of the front. Seas of 11 to 13 ft are within the area of these winds. These conditions are expected through Sunday morning.

...Tropical Waves...

A tropical wave has its axis along 44W from 03N-16N and is moving west at 10-15 kt. The wave corresponds nicely with a maximum in TPW imagery. Model analyses depict an associated 700 mb trough along 44W. Scattered showers are located near and east of the wave axis from 10N-13N between 38W-44W.

A western Caribbean tropical wave has its axis along 87W from 09N-21N, moving west around 10 kt. The 700 mb trough associated with this wave is well depicted in model guidance, and TPW imagery shows abundant moisture in its environment. Scattered moderate convection is noted south of 20N between 85W-90W. Moisture associated with this wave will continue to spread inland across Central America through the weekend, enhancing similar convection across this area.

...The Caribbean Sea...

A tropical wave is moving across the far western Caribbean, and a portion of this wave is entering Central America. Please see the Tropical Waves section for more details.

The eastern Pacific monsoon trough combined with diffluence aloft continues to enhance convection over portions of Panama and the waters of the southwest Caribbean from the coasts of Panama and Costa Rica northward to 13N and eastward to 78W. Plenty of moisture will persist over the extreme southwest Caribbean, Panama and Costa Rica through the weekend. Elsewhere, fresh to strong winds prevail over the central Caribbean. These winds will diminish across most of the basin by tonight.

Climate Prediction Center's Central America Hazards Outlook


48 Hour Forecast - Favorable Environmental Conditions For Tropical Development



Infrared Satellite in Belize City

Tropical Storm Kirk is south of the Cabo Verde Islands, while a depression is east of the Windward Islands
Accuweather

September 23, 2018

Tropical Storm Kirk is located at 9.1° N, -28° W with maximum sustained winds of 40 mph and gusts to 50 mph, moving W 18 mph, pressure 29.71 in / 1006 mb.

Tropical Depression 11 is located at 14.5° N, -55° W with maximum sustained winds of 30 mph and gusts to 40 mph, moving NW 6 mph, pressure 29.80 in / 1009 mb.

Tropical Storm Kirk is located 465 miles south-southwest of the southernmost Cabo Verde Islands with maximum-sustained winds of 40 mph. Kirk is moving to the west at 15 mph and will not be a threat to land during the next few days, but could threaten parts of the Windward Islands Thursday night and Friday of this coming week with strong perhaps damaging winds and heavy rainfall. Kirk is moving through an environment of warm water and within an area of relatively low shear. These two important factors should allow Kirk to intensify. However, the air mass this storm is tracking through is drier than normal and this could limit intensification.

Tropical Depression 11 is located 415 miles east-northeast of the Windward Islands. This weak tropical cyclone is forecast to weaken to a non-tropical area of low pressure within the next day or two as it moves slowly to the west and northwest. What is left of this system will move through the Lesser Antilles with more clouds, heavier showers and gusty winds. Residents and interests in the Lesser Antilles should closely monitor this system.

An area of low pressure centered about 225 miles south-southwest of Bermuda is moving south-southwest and will eventually move more westward Sunday. This system has the potential to acquire some tropical characteristics next week as it tracks over warm water and turns more northwesterly. This could lead to the development of a tropical depression or tropical storm as the system approaches the Carolina coast Tuesday night and Wednesday of this coming week. All residents and interests along the southeastern coast of the United States should monitor this system.

Finally, an area of low pressure has formed about halfway between Bermuda and the Azores as planned. This system might acquire some tropical characteristics during the next couple of days and become a subtropical or tropical storm during next week. The system will remain trapped between to areas of high pressure through next week. So, the system is not expected to be a threat to land for the next several days.



120 Hour Forecast - Favorable Environmental Conditions For Tropical Development

Tropical Depression #11 Likely To Dissipate Sometime Today; Tropical Storm Kirk, Now Located Over The Eastern Tropical Atlantic May Impact The Lesser Antilles Late This Week; Invest 98-L May Bring Gusty Winds & Some Rainfall To The Outer Banks Of North Carolina Tuesday Through Wednesday
Rob Lightbown of Crown Weather Services

September 23, 2018

Satellite imagery this morning indicates that Tropical Depression #11 is very poorly organized and is likely now a weakening tropical wave. It is expected that this system will encounter even stronger wind shear over the next couple of days leading to dissipation as soon as later today or on Monday.

This means that Tropical Depression #11 is of no threat to the Lesser Antilles.


Tropical Storm Kirk:
5 am EDT/4 am CDT Statistics:
Location: 9.1 North Latitude, 28.0 West Longitude or about 465 miles to the south-southwest of the Cabo Verde Islands.
Maximum Winds: 40 mph.
Minimum Central Pressure: 1006 Millibars or 29.71 Inches.
Forward Movement: West at a forward speed of 18 mph.

It appears that the overall structure of Kirk is gradually becoming more organized this morning. Recent satellite imagery indicates that there has been an increase in the overall thunderstorm activity which began last night. In addition, there seems to be some curved bands of convection trying to form.

The environmental conditions around Kirk are favorable for further strengthening as the storm is embedded within an area of relatively low wind shear (Less than 20 knots) and there doesn’t seem to be any dry air impinging on the circulation. Based on my analysis, it appears that Kirk may remain within a favorable environment for strengthening for at least the next couple of days before stronger wind shear begins to impact the storm. This means that if Kirk remains within this favorable environment, a run at hurricane strength is not out of the question by the middle part of this week. It should be noted, however, that most of the intensity guidance keep Kirk as a tropical storm throughout this coming week.

Kirk is moving on an almost due west heading as a ridge of high pressure to its north controls it. It is likely that Kirk will increase in forward speed over the next couple of days and this could lead to the low-level circulation outrunning the thunderstorm complex. Should this occur, then weakening instead of strengthening is highly likely as the storm would create its own shear based on its fast forward motion. This is likely why most of the global model guidance forecasts very little strengthening in the coming days.

Here Are My Thoughts: I do think that there is the very real possibility that Kirk will impact some part of the Lesser Antilles as a 40-60 mph tropical storm on Friday. Barbados and all of the Windward Islands are at highest risk right now, but Guadeloupe and Antigua should also closely monitor the progress of Kirk as a slightly more northward track would lead to tropical storm conditions here as well.

Fortunately, we still have plenty of time to keep an eye on Kirk and I urge everyone across Barbados, the Windward Islands and the southern Leeward Islands to closely monitor the progress of Kirk.

Beyond this, I think that we will need to keep a close eye on the track of Kirk when it pushes into the Caribbean next weekend. The European ensemble guidance seems to lose Kirk in the eastern and central Caribbean, but then a few members forecast the redevelopment of the storm in the western Caribbean during the first week of October. Eventually, 4 of the ensemble members forecast some sort of impact on either the Bahamas or Florida during the weekend of October 6-8.

In addition, the GFS ensemble guidance seems more active with Kirk in either the Caribbean or near the Bahamas. Even though 50 percent of the 21 members forecast eventual dissipation of the storm, the other 50 percent forecast that Kirk will get trapped underneath a large high pressure system over the northeastern United States and driven westward. This leads to Kirk getting close to or directly impacting the southeastern US during the first week of October. In fact, 3 ensemble members forecast a direct impact on Florida with 1 member forecasting a track into the Gulf of Mexico.

I do still think there are at least two possible scenarios with Kirk. The first is that it could become a “Caribbean Cruiser” that ends up reaching the western Caribbean during the first week of October. The second possibility is that Kirk may be lifted northward out of the eastern Caribbean next weekend and be a threat to Puerto Rico and Hispaniola as well as the Bahamas next weekend into the first week of October.

Bottom line is that I am keeping a very close eye on Kirk and will continue to have updates for you as conditions warrant.

Model Track Forecast For Kirk:


Invest 98-L Located Between Bermuda & The Bahamas: An area of low pressure is located about halfway between Bermuda and the Bahamas. Satellite imagery indicates that there continues to be a lack of robust thunderstorm activity occurring with this system, although the thunderstorm coverage is a little higher as compared to this time yesterday. The wind shear values around Invest 98-L have decreased to 10-20 knots and it appears that we may see favorable environmental conditions for development continue until about Tuesday before the wind shear values increase again.

The most certain part with the forecast of Invest 98-L is that it is expected to head westwards towards the US Southeast Coast and will likely be very close to the North Carolina coast around Wednesday. The much less certain part of the forecast is whether Invest 98-L will develop into a tropical depression or a tropical storm over the next couple of days or so. If we continue to see an increase in thunderstorm activity today through Monday, then I think we could definitely see this system become a tropical depression and maybe even a low end tropical storm by the time it reaches the area near the North Carolina coast late Tuesday into Wednesday. On the other hand, if we see thunderstorm activity fail to organize anymore than what it is now, then very little development would likely occur.

Either way, Invest 98-L will bring some gusty winds and a few bands of rainfall & embedded thunderstorms across the outer banks of North Carolina Tuesday through Wednesday. I am monitoring Invest 98-L very closely and will have additional updates for you as conditions warrant.

Invest 98-L Information:

Model Track Forecast:



Kirk Forms in Eastern Atlantic; TD 11 Little Threat
Jeff Masters, Category 6

September 22, 2018

A tropical wave dubbed 99L that emerged from the coast of Africa on Thursday night became Tropical Storm Kirk on Saturday morning, and may pose a danger to the Lesser Antilles Islands as early as Wednesday night. Kirk was located about 450 miles south of the Cabo Verde Islands at 11 am EDT Saturday, when it was upgraded by the National Hurricane Center to become the Atlantic season's 11th named storm. The Atlantic does not typically get its 11th named storm until November 23, based on 1966-2009 climatology.

Kirk was headed west at about 14 mph with top sustained winds of 40 mph. Satellite images on Saturday morning showed that Kirk was well-organized, with a well-defined surface circulation evident in ASCAT scatterometer data. The system had only a moderate amount of heavy thunderstorms, which were clumpy and did not appear well-organized. Upper-level outflow was apparent on the north side, and Kirk had one decent-looking low-level spiral band on its east side.

Saharan Air Layer (SAL) analysis
Figure 1. Saharan Air Layer (SAL) analysis for 8 am EDT September 22, 2018. The dry air of the SAL (orange colors) lay well to the northwest of Kirk, but was strongly affecting TD 11 and 98L. A developing non-tropical low pressure system in the Central Atlantic will likley be designated 90L by Sunday. Image credit: University of Wisconsin/CIMSS.

Kirk's future

The 12Z Saturday run of the SHIPS model predicted that SSTs along Kirk's path would remain nearly constant through Sunday, then steadily increase to a warm 29°C (84°F) by Tuesday. During this time, the atmosphere was predicted to stay moist, and wind shear light to moderate. These conditions should allow Kirk to continue strengthening gradually this weekend, and SHIPS indicates a slight chance that Kirk could undergo a period of more rapid intensification. However, Kirk's development may be limited by its rather low latitude (near 8 - 9°N), and over time Kirk will be hindered by its rapid forward speed, expected to increase to 20 - 25 mph by early next week. Only one of the operational 0Z Saturday runs of our top three models for predicting tropical cyclone development--the UKMET model--had predicted that 99L would develop into Tropical Storm Kirk. However, there was support for development from about 30% of the 50 members of the 0Z Saturday European model forecast, and over 50% of the 20 members of the 0Z Saturday GFS ensemble forecasts.

Kirk's speedy westward motion over the next several days could bring it into the Lesser Antilles Islands as early as Wednesday night, though an arrival on Thursday, as predicted by NHC, is more likely. Wind shear is predicted to increase to a high 20 – 30 knots by Wednesday and increase further on Thursday. Kirk will likely be weakening as it approaches the Lesser Antilles, and none of the ensemble members from 0Z Saturday predicted that Kirk would survive its trek through the eastern Caribbean.

TD 11 forms east of the Lesser Antilles

Despite high wind shear and dry air, Invest 98L shrugged off being given only a 10% chance of development on Friday morning, developing into a tropical depression on Friday night in the waters about 500 miles east of the Lesser Antilles. However, conditions have grown even more hostile for the depression, with wind shear a high 30 – 35 knots on Saturday morning. Satellite loops on Saturday morning showed that the depression was unraveling, with its center of circulation becoming difficult to find and its heavy thunderstorms becoming weak and disorganized. With wind shear predicted to increase to a very high 40 knots by Saturday night, TD 11’s hours are numbered, and expect the system to dissipate by Sunday without affecting any land areas.

A portion of Florence’s remains could develop next week

The Saturday morning runs of our top three models for predicting tropical cyclone genesis—the European, GFS, and UKMET models—all predicted development by Tuesday of a non-tropical surface low pressure system that closed off on Saturday in the Central Atlantic, about 900 miles west-southwest of the Azores Islands. This low is being invigorated by a portion of Florence’s remnants. SSTs are unusually warm in this region, about 25 - 26°C (77 -79°F), which is more than 1°C above average. The low will get cut off from the jet stream and meander in an area of weak steering currents for many days. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave this system 2-day and 5-day odds of development of 60% and 70%, respectively. The next name on the list of Atlantic storms is Leslie.

98L near Bermuda no immediate threat

A non-tropical low pressure system was located about 200 miles south of Bermuda on Saturday morning. This system (98L) has lost all of its heavy thunderstorms, and high wind shear and dry air should keep any development slow. The low is expected to move to the southwest of Bermuda by early next week, and then loop back to the northwest and bring rain to the Southeast U.S. as early as Tuesday. The 6Z Saturday GFS model predicted that 98L would bring less than an inch of rain to Eastern North Carolina Tuesday through Wednesday, though. None of our top three models for predicting tropical cyclone genesis—the European, GFS, and UKMET models—predicted that 98L would develop into a tropical depression. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave 98L 2-day and 5-day odds of development of 10% and 30%, respectively.

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Last edited by Marty; Yesterday at 08:45 AM.