91L – Likely Tonight/Tomorrow Tropical Depression 5 possibly TS Emily

The National Hurricane Center as of 8pm EDT July 30 2011 is giving this wave a 90% chance of developing into a tropical cyclone within the next 48hrs.

I believe from what I see, a Tropical Depression will form sometime in the early morning hours EDT. The tropical wave at this time is elongated along a west northwest to east southeast axis and still has no well-defined center. It appears there may be two areas within fighting to see which will remain. Until there is a defined center, it is hard to determine where this tropical systems track will take it. Computer models are coming more inline, but still differ enough that no one knows where it will go at this time.

This system is becoming better organized as seen from this infrared image.

Computer model forecast track –

Earlier posts on this system: here & here

Tropical Storm DON, 91L and another tropical wave

First a little about Don, which as I write [ 8:14 PM EDT 7/29/2011 ] is nearing landfall north of Brownsville Texas with winds of 50 mph. I was wrong. I said Don would make landfall somewhere between Corpus Christi and Galveston, Texas. That was 2 days ago, before Don took a jog on a more southerly path. Hey what do you want form an amateur. Even the pros are wrong sometimes, and no one really knows where a tropical system will go until it gets there. I’m not making excuses.

With Tropical Storm Don making landfall, I will now turn my attention to a tropical wave mentioned earlier today. This wave now called 91L is located at this time about 1100 miles East-Southeast of the Lesser Antilles. As of the 8pm EDT update from the National Hurricane Center, this wave now has a ‘well defined low pressure system’ associated with it. This wave is moving 15 to 20mph and is heading westward or west- northwestward. This tropical wave is now being given a 50% chance of developing into a tropical cyclone in the next 48hrs.

There is also another tropical wave located in the western Caribbean showing disorganized showers and thunderstorm activity, moving westward at 10 to 15moh. This wave is not forecast to become a tropical cyclone in the next 48hrs and has a 0% chance of doing so.

Turning our attention back to invest 91L. Should 91L strengthen to a tropical storm, it will be known as Emily. If this happens and a name is given, Emily will be the 5th named storm of the 2011 hurricane season and also put us at having five named storms before August 1st. Near as I can find this only happened in the 2005 season. Please correct me if I’m wrong here!

Other than being upgraded as far as becoming a tropical cyclone in the next 48hrs not much has changed with this feature. Early computer models expect 91L to strengthen as it moves west northwestward in the coming week. It is early and we really have no idea what 91L will do. Intensity models vary as they will. Some, the GFD and the GHM2 strengthen 91L as much as a category 3 hurricane. Others at this time keep 91L at a category 1 and still others keep it a strong tropical storm.

Models predict this tropical system to continue on it’s westward path taking it near Puerto Rico and the northern Leeward Islands. Most of the models show this system impacting Hispaniola at this time. As mentioned computer models vary and some of them show this system re-curving back out into the Atlantic after its brief interlude with the Caribbean becoming what many call a ‘fish storm’ [ a fish storm only affects the fish, no land mass ]. It is early and things can and will change. This is a system to watch in the coming week.

Computer model graphic –

Tropical Storm DON heading for Texas – Another Tropical Wave to watch

Tropical Storm DON still moving through the Gulf showing little change. Winds 50mph, Pressure 1000mb, moving WNW at 14mph. Another Tropical Wave 1200 miles East-Southeast of the Lesser Antilles is showing signs of development. The national Hurricane Center is giving this wave a 30% chance of becoming a tropical cyclone in the next 48hrs. This wave is moving West-Northwestward at 15 to 20mph.

Via National Hurricane Center

A LARGE TROPICAL WAVE ACCOMPANIED BY A WELL-DEFINED LOW PRESSURE SYSTEM IS LOCATED ABOUT 1200 MILES EAST-SOUTHEAST OF THE LESSER ANTILLES. THIS DISTURBANCE IS SHOWING SIGNS OF ORGANIZATION…AND ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR GRADUAL DEVELOPMENT OVER THE NEXT FEW DAYS. THIS SYSTEM HAS A MEDIUM CHANCE…30 PERCENT…OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD OR WEST-NORTHWESTWARD AT 15 TO 20 MPH.