Monthly Archives: October 2010

Invest 99L

The area of disorganized showers and thunderstorms within the southwestern Caribbean Sea has now been designated as Invest 99L. Only a few of the models are seeing any type of organization so we will have to see if any other models fall in line but there are is only a few days before landfall will occur.

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Hurricane season ending?

At the moment there is nothing tropical and things seem to getting where conditions for tropical development will be difficult to do. Hopefully the hurricane season will be ending early.

There are some disorganized showers and thunderstorms within the southwestern Caribbean Sea. The GFS and the Canadian models are the only models that support any development. Even if that area does develop into something tropical, the synoptics are for whatever is there – will eventually head west and landfall near Nicaragua.

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Tropical Storm Paula

Hurricane Paula has been downgraded to Tropical Storm Paula as of the 11am advisory from the NHC. Tropical Storm Paula has been hugging the coastline of western Cuba and is beginning to shear apart. The decoupling of the different layers of the storm have been showing up on satellite for the last 8 hours or so. With southwesterly shear, dry air entrainment within the core of system, along with land interaction, Tropical Storm Paula will continue to fall apart and should be a Tropical Depression then just a remnant low pressure system even faster than forecasted – possibly within less than 48 hours.

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Hurricane Paula – A category two hurricane

Hurricane Paula, a very small but category two hurricane is now nearing the Yucatan Channel heading just east of north but Paula is expected to make a turn to the northeast then east. The forecasters at the NHC are very certain that this turn will happen but it is how much of the turn that is still unclear. Paula will become embedded in a westerly to easterly flow that is associated with the base of a deep mid-latitude trough. Some models want to take Paula on a sharp easterly track over Cuba where as other models want to take Paula on a more ENE motion.

Because of the uncertainty on both the track and the intensity, a Tropical Storm WATCH has been issued for a portion of the Florida Keys.

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Hurricane Paula

Tropical Storm Paula has been upgraded to Hurricane Paula as of the 5am advisory from the NHC. Hurricane Paula is forcast to strengthen to a possible category two hurricane, but this will for a very short time. Heat Oceanic content is very high right now and for the next few days but the atmosheric conditions will become less conducive for development as southwesterly upper level winds are forecast will begin to impact Hurricane Paula and a day or two later, dry air will be pushing southward and toward the center of circulation. Paula will is forecast to track to the NW then northward around the western periphery of a Mid-to Upper level ridge that is located over the northern Caribbean Sea. Model guidance is poor at best as there is no model consensus. The GFDL wants to make Paula a stronger system and head NE into Cuba and then into the Bahamas whereas the GFS, ECMWF, and HWRF want to keep Paula as a shallower and weaker system and keep Paula into the Western Caribbean and in some cases have landfall into Nicaragua. Since the forecast is for the upper level winds along with the drier air, the forecast is to follow the latter models BUT since the model guidance confidence is low, the GFDL guidance cannot be ruled out.

ADDENDUM: At 1:45pm EST the recon plane found winds of over 85knots or about 100MPH. Hurricane Paula is now a category 2 storm. Further strengthening for the next day or two is still forecast.

Below is the GFDL Model:

Below are the GFS, ECMWF, & HWRF Models:

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Tropical Storm Paula

Invest 98L has been upgraded to Tropical Storm Paula as of the 5PM advisory from the NHC. Recon earlier today found winds of 60 MPH, but that might be a little conservative. The forecast is for Tropical Storm Paula for additional strengthening and Paula is forecast to possibly become a hurricane within 24 hours according to the models SHIPS, and LGEM. Strengthening will only be possible for a few days, then slow weakening on days 4 or 5. For the next few days the track for Paula will be NW then N. The western edge of a ridge that extends across northern Caribbean is expected to weaken because of a deep-layered trough that will be moving eastward across the Southeastern US. After that forecast period most of the guidance is suggesting that the trough will move east and then leave Paula in an area of weak steering currents and Paula is expected to drift eastward for for a day or two then possibly drift southward. Model guidance after day 3 or 4 and confidence is quite low. Whether Paula will stay in the Western Caribbean and impact Nicaragua or head north and northeast unfortunately it is too difficult to forecast.

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Invest 98L & Tropical Storm Otto

Invest 98L which has been lingering for many days has been getting better organized and may become a Tropical Depression or Tropical Storm in the next day or two but time will be running out as land interaction will halt any further chances of development. All the Global models are now keeping Invest 98L within the Western Caribbean basin. Invest 98L will continue to head WNW or NW and most likely will have landfall in Nicaragua and Honduras. A large area of dry air to the NW and N of 98L along with a few more troughs are in a zonal flow (west to east) within the US will keep Invest 98L from heading north to the to the US.


Tropical Storm Otto, way out in the mid Atlantic which at one time was a hurricane, was downgraded to a Tropical Storm yesterday and has been slowly been losing strength and tropical characteristics. Otto will be fully extra-tropical within 24 hours. The NHC is no longer tracking Tropical Storm Otto as of the 11am advisory.

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Invest 98L & Otto

The system in the Western Caribbean has now been designated as Invest 98L. A few of the models want to take the system North and then turn NE over Cuba. The GFDL and HWRF want to let this system spin up into a tropical storm and hurricane. Although, at the time this cannot be discounted, most of the other models want to keep the system in the Caribbean. There is some cyclonic turning but convection has not been sustained over several hours. There is a very large area of dry air to the North, Northwest, and West of Invest 98L (as shown in the Water Vapor image below).


Hurricane Otto, still classified as a tropical cyclone with top winds of 85MPH will soon start the transition from tropical to extra tropical but gradually. Otto is between a large deep-layer trough of the coast of the US and a subtropical ridge over the Eastern Atlantic.

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Hurricane Otto

Tropical Storm Otto has been upgraded to Hurricane Otto as of the 11am advisory from the NHC. During the past 6 -12 hours satellite images showed that Otto had developed a well defined and large CDO – Central Dense Overcast. (This is the cirrus cloud shield that results from the thunderstorms in the eyewall of a tropical cyclone and its rain bands). Otto in an environment with light shear marginally warm waters which will allow some further intensification but gradual. This will be short lived as within 24-36 hours, southwesterly shear and cooler waters will take it’s effect on Otto and weakening if forecast. Otto will begin the transition from tropical to extra tropical within 48 hours. Otto has been heading ENE and gradually has been accelerating. Otto will stay on this track for 2 or 3 days and eventually turn to the eastward then southeastward due to a deep layered trough. Otto is expected to affect those in the Azores Islands.

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Tropical Storm Otto

Sub Tropical Storm Otto finally made the transition to a tropical cyclone and as of the 11am advisory from the NHC Otto has been upgraded to Tropical Storm status. The warm core of Otto has moved up from the mid levels all the way to the upper levels. This will allow Otto to have a better chance to develop into a hurricane for the next day or two and help make a smaller inner core. Warm SST’s and vertical shear is forecast to be at 10 knots or less and Otto is forecast to attain hurricane status. After that forecast period, upper level winds will increase and Otto is forecast to merge with a frontal system. Otto is forecast to become post tropical/extra tropical in 96 hours. At the moment, Otto has been quasi-stationary for 6-8 hours but a slow drift to the NE is forecast. Once Otto has merged with the frontal system, Otto will be accelerated and track ENE and possibly affect those in the Azores Islands.

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