97L continues to grow more organized; headed for Bahamas and Florida
A tropical wave (Invest 97L) between Puerto Rico and the Dominican Republic has continued to become more organized today, and is a threat to develop into a tropical depression as early as Wednesday morning. The disturbance has brought heavy rains of 8+ inches to Culebra and Vieques islands over the past day, and all of Puerto Rico and the Virgin Islands are under flash flood watches today. The storm could bring an additional 3 - 6 inches of rain to the islands over the next two days. The upper level low centered a few hundred miles north of the Dominican Republic is no longer bringing high levels of wind shear to 97L; wind shear has fallen to the moderate range, 10 - 15 knots, which should allow 97L to continue to develop today. Satellite images of 97L show a moderate area of steadily organizing thunderstorms, with curved bands developing to the north and east of the center. There are no signs of a surface circulation on satellite imagery or on the 10:38am EDT ASCAT pass. Surface observations show only light winds over Puerto Rico and the Dominican Republic, but the surface winds at Punta Cana on the eastern tip of the Dominican Republic have shifted to the west this afternoon, indicating that a surface circulation may be forming just north of that location. Long-range radar loops from San Juan do not show any evidence of a surface circulation. The Hurricane Hunter mission scheduled for today was canceled, but is scheduled to fly Wednesday afternoon.
Figure 1. Total precipitation from 97L as predicted by the 12Z (8 am EDT) July 20, 2010 run of the HWRF model. Image credit: Morris Bender, NOAA/GFDL.
Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of isolated flooding to the Dominican Republic today and Wednesday, and to Haiti on Wednesday and Thursday. Heavy rains from 97L will begin moving into eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas on Wednesday, and South Florida can expect heavy rains to arrive as early as Thursday night. The latest suite of model runs from 8am EDT this morning (12Z) foresee a more northerly track for 97L into Central Florida. Several models develop 97L into a tropical storm, with both the GFDL and HWRF models predicting 97L will hit South or Central Florida as a tropical storm on Friday. Most of the models have 97L entering the Gulf of Mexico on Saturday, but the amount of time 97L has over the Gulf may be limited to a day or less if the storm ends up exiting into the Gulf near Tampa Bay. The NOGAPS model predicts a more southerly path across South Florida and into Louisiana.
Intensity Forecast for 97L
One factor potentially aiding development of 97L will be the Madden-Julian oscillation, which currently favors upward motion over the Gulf of Mexico and Caribbean. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. Also in favor of development are the warm ocean temperatures of 29°C. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next five days. The primary detriment to development of 97L over the next three days will probably be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. If the center forms close to the coast of the Dominican Republic, the high mountains of Hispaniola may also be a problem for the storm. NHC is giving 97L a 60% chance of developing into a tropical depression by Thursday, which is a reasonable forecast. I think there is a 70% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development today or on Wednesday is unlikely, due to the dry air over the Bahamas. I put the odds of 97L making it to hurricane strength before reaching Florida at 30%, and I give a 20% chance it will be a hurricane in the Gulf of Mexico. The probability of 97L being a hurricane in the Gulf of Mexico will depend heavily upon how long the storm spends over land or interacting with land over the next four days, which is very uncertain.
"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:
1) Invest 97
2) A look ahead at the coming two weeks
Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.
Jeff Masters
Reader Comments
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Morning. Same forecast here.
GFS 6Z shows no threats through August 6th.
Ditto the parallel GFS through August 6th.
Oh yeah...no doubt...big-time.
Remember people...it's just the weather. There's nothing anyone can do about it.
Your Resident Toastcaster..
And TS's this morning.
Right now I would say no.
it appears that a new centre is trying to form in the heaviest convection over the leeward islands. i suspect the area east of the DR where the NHC is pinning the LLC will wane as the day progresses, we must also focus on the area of disturbed weather which is now off the african coast
Well, if I remember correctly people were saying the possibility of a Hurricane or Tropical Storm forming were High. some were even giving it 80%. People were jumping to fast on the bandwagon. It happen with tropical Storm Chris and the result aren't always pretty.
could the system actually be developing further east toward antilles
Morning Ike, Thats why being wrong when guessing the weather is nothing to be ashame about. Its always changing
Shear and some Dry air affecting 97L at this current time.
97l is moving slightly east.
I hate to toot my own horn but thats exactly what i said from the getgo. I didnt feel the factors were there for an explosive season. Ive been saying that all along. I rely think a bust is possible unless action starts in august.
This. The impatience on this blog astounds me. Drak alluded to this same thing several weeks back.
Shear sure keeping 97L in check.
Agree. But, I don't think the TUTT will be this strong and south by August and September.
I also value humility; it is one of the hardest characteristics to possess, however.
its on life support dry air boundary is near where the center is. ULL continues to creep a little further south. get the defibralator ready
Well to be honest, I wasn't expecting development to occur today. I expected it tomorrow, and still do.
I'll admit that I wasn't expecting such a significant wane in convection, though. But it's as I said, a lot of people are laughably impatient to the point of absurdity. I'm not even a very patient person myself, yet even I know better than to write systems off based on a period of convective waning.
That it is, mate. That it is. But it's vastly important.
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