No Tropical Development is Expected

Last Update: 21-NOV-2009 06:15am EST

The tropical Atlantic remains quiet. No tropical development is expected through the weekend.





http://hurricane.accuweather.com/

I plan to be in Caye Caulker this Friday thru tuesday. weather forecasts say thunderstorms everyday. Does that mean nice beach weather then an afternoon thunderstorm, then clear again? or overcast storms all week?

Would really appreciate any input as I have the option to postpone the vacation if the weather is not conducive to enjoy the beach, ocean, etc. some thunderstorms would be enjoyed as well...

Thank you

ignore those forecasts. the rain generally falls briefly on the cayes

:-)
yep, da Sooth speak!

Good news. Guess I'll get on the plane tomorrow. Thanks for the beta

Rob Lightbown of Crown Weather has the following comments on what we might expect in the next few weeks.

Possibility For An Active End of September Into Early October:

Looking at the overall pattern across the entire Atlantic Basin, it appears that a pattern change is coming. Currently, much of the Atlantic Basin is unfavorable for tropical development due to the combination of strong wind shear and sinking air. It appears that another upward pulse in the Madden Julian Oscillation (MJO) may arrive in the Atlantic by the end of this month and continue into early October. This will have to be watched very closely as there are signs in the long range model data that the Caribbean Sea and Gulf of Mexico may become more active over the next 3 to 4 weeks. I am not and I repeat NOT forecasting a hurricane for these areas, but I am saying that these areas will need to be monitored very closely for tropical development as we head into late September and early October. Whether something forms remains to be seen, but it will be watched closely.

Rob Lightbown of Crown Weather gives us this brief update on what we might expect in the next week or two.

Considering it’s late September, things are very quiet in the tropical Atlantic. Tropical Depression #8 formed yesterday in the far eastern Atlantic and it is forecast to be pulled northwest and northward into the open Atlantic over the next couple of days and is expected to dissipate in about 3 to 4 days.

Satellite imagery also showed a more impressive tropical disturbance located to the southeast of TD 8 and is located just off of the coast of Africa. This disturbance is at a further south latitude and it may slowly organize over the next few days. None of the forecast guidance forecasts that this disturbance will develop, however, environmental conditions may be favorable enough to warrant keeping an eye on this disturbance, however, any development will be slow to occur.

Elsewhere, there is no other areas of concern this morning and the forecast guidance forecasts no tropical cyclone development for at least the next 5 to 7 days. It should be noted, however, that the European model keeps forecasting some type of tropical development in the southwest Caribbean in about 7 to 9 days (October 3rd to October 5th). As for the other model guidance, the NOGAPS model forecasts some sort of tropical system to form in the southwest Caribbean on Friday and forecasts it to be located just offshore of the coast of Honduras and Nicaragua next Saturday. The GFS model only hints at something forming, but never really closes anything off. This is a climatologically favored area for development in October, so this is something that will need to be watched for closely.

From Dr. Jeff Masters / Weather Underground

Invest 91
A large tropical wave near 12N 46W, about 1000 miles east of the Lesser Antilles Islands, is generating a considerable amount of heavy thunderstorm activity as it moves west-northwest at 15 mph. The wave is under low wind shear, 5 - 10 knots, and is over warm waters, 29°C, which is 3°C above the threshold typically needed to allow tropical storm formation. Last night's QuikSCAT pass <http://manati.orbit.nesdis.noaa.gov/dataimages21/cur/zooms/WMBds26.png> showed a large and disorganized region of converging winds in the region, with top winds of 25 mph. There is very little dry air in the vicinity, and conditions appear favorable for some slow development of this wave. The wave is poorly organized at present, with no signs of a surface circulation visible on satellite imagery. None of the computer models develop the wave, but they do show relatively low wind shear along the wave's path for the next five days. The wave should continue to track west-northwest over the next 2 - 3 days, and spread heavy rain showers over the northern Lesser Antilles Islands by Wednesday. By Thursday, the trough of low pressure that is pulling 91L to the north should bypass the storm, allowing a high pressure ridge to build in and force 91L due west. NHC is giving 91L a low (less than 30% chance) of developing into a tropical depression by Wednesday.

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Since the posting above, NHC has increased the chance of development to "medium" - 30-50%.



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Rob Lightbown / Crown Weather posts:

I am keeping a close eye on a tropical disturbance, labeled Invest 91L <http://www.wunderground.com/tropical/tracking/at200991_model.html> . This disturbance is producing widespread, but disorganized, showers and thunderstorms and is located about 1150 miles east of the Lesser Antilles. This disturbance is under somewhat favorable environmental conditions and slow development seems likely, especially since it is so large in size as larger disturbances take longer to organize and develop. None of the global model guidance develops this system and this should be taken in account as the global models may be catching onto an environment that is not that favorable. The hurricane track models and hurricane intensity models forecast that Invest 91L will slowly intensify and may become a tropical storm over the next 2 to 3 days or so as shear values are forecast to be favorable over the next 24 hours and then become unfavorable during Tuesday and Wednesday and then become favorable again late this week. So, my thinking is that slow development seems possible over the next few days.

Again, what is interesting to me is that the global computer guidance forecasts development in the short term and then forecasts it to “poof” later this week. I’m not sure what the global models are seeing as conditions appear that they will become favorable as we head into late this week with a large area of high pressure building over and to the north of this disturbance. The fact that the global models are not developing this disturbance may be a good sign that nothing will come of Invest 91L.

If Invest 91L does develop, the steering flow suggests that it may track through the Caribbean and then turn to the north as it reaches the western Caribbean as a frontal system tracks into the Gulf of Mexico and across Florida by this weekend. This would be considered a classic October setup and I am hoping Invest 91L goes “poof” and that we don’t have to worry about it. At this time, Invest 91L does have my attention and I will be watching it closely

http://www.wunderground.com/tropical/tracking/at200991_model.html
my favorite weather site

Posted by: JeffMasters, 2:06 PM GMT on October 06, 2009
A tropical wave (91L) near 17N, 52W, about 550 miles east of the Lesser Antilles Islands, continues to generate considerable heavy thunderstorm activity as it moves northwest at 15 mph. The wave is under high wind shear, 20 - 25 knots, and is over warm waters, 29°C. This morning's QuikSCAT pass showed no closed circulation, and top winds of 30 mph. However, satellite loops show that 91L now has a closed surface circulation, though strong upper-level winds out of the west are keeping the heavy thunderstorm activity confined to the east side of the center. Since there is not much dry air to the storm's west, the shear will not have as great a negative impact as we've seen in similar high-shear situations this year.

None of the computer models develop the wave, and they show moderate to high wind shear affecting 91L over the next 2 - 3 days. The storm will be steered northwest for the next 2 - 3 days by a trough of low pressure passing to the north. The northern Lesser Antilles may see some heavy rain showers and gusty winds from the southern portion of 91L on Thursday and Friday. By Friday, the trough will have passed far to the east, and high pressure will build in, which may force 91L to the southwest into the Caribbean, according to some model projections. Wind shear is expected to fall to the low to moderate range 3 - 5 days from now. If 91L holds together for the next 2 - 3 days and avoids interaction with the high mountains of Hispaniola late this week, the storm could be trouble. NHC is currently giving 91L a low (less than 30% chance) of developing into a tropical depression by Thursday, and the Hurricane Hunters are not on call to fly the storm. I think the storm has more potential to develop than NHC does, and put the odds of development over the next two days at medium (30 - 50%).