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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Because a stream of SW wind does not mean that same stream of wind clocks all the way around.
Air is being sucked north through the Mona no doubt.
it is rising to the north of the passage in all the convection no doubt and out flowing to the N and NE no doubt..you can see the whole thing on radar and sat..
but that is still a linear flow...
it would be circular due to the Coriolis effect except for the fact the mountain of the islands are funneling the winds...
definitely organizing. let the games begin
I agree Homer...
Seems from the steering it could go just to the South of Mainland Fla and cross the keys.
Hope y'all dry out soon.
TAZ.. Why is he still here?????
yup this read back 27 page and you find all the info you need
A moderate possibility. It would not surprise me, but I am looking to see how favorable the upper environment gets.
Regardless of intensity I suspect the system will affect South Florida.
Mean Temperature: 82 °F
Dew Point: 74 °F
Average Humidity: 78
Sea Level Pressure: 29.89 in
Wind Direction: WSW
Wind Speed 14 mph ()
Tropical waves are some of the most erratic storm systems on the face of the earth. Sometimes they can spin up out of nowhere overnight, and sometimes even under the most favorable conditions they still can't get a circulation going.
So can we at least wait until this thing has a LLC before we start predicting how strong it will be? Once it does, then it will become more predictable, and we can start truly speculating rather than just doomcasting or downcasting.
Puerto Rico NWS Radar:
Hi there, did you get to see forecast made by Vaughn on his 6:30 broadcast. He out and out said this was most likely a TX storm. Leaves me scratching my head.
reported
i see a 1004mb low in 48hrs way out there and am not talking about 97L
Even though the surface circulation is forming, I do not think it will get define enough by tomorrow morning. I will give 97L another 24 hrs, atleast, so if all goes well (from the system's point of view) then 2mr evening seems the best bets. Likely after reccon gets there.
my thoughts also 456. Just wondering what 97L will do when it hits the Gulf stream.
21/1800Z
yup
darn that stinks... lol
models going to shift further south next run?
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