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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The TPW and the 850 vort both say that it's right on the coast of the DR, and on close view of the area there IS a slight circulation that existed in the lower clouds right before sundown, if you track that in time to now it does keep spewing local convection right along the coast, including one recent burst where I think is right over the center. CMISS maps has also up'ed the convergence in that area over the last few hours.
However... the convection is all by itself and heading into a pretty hefty area of shear over the next 12 hrs. Overall I'd give it a 20% of devloping into a TD over the next 24 hrs.
Sources:
Sat Imagery
Total Precipital Water
Shear,convergence and divergence, vorticity.
i seriously doubt that in 24 hrs we will all be debating why we have a yellow invest as opposed to the code red we have now
same here the ULL, shear, dry air and terrain should keep this from being much more than a raim event unless something drastic happens. but it does look like for the first time there is a definite swirl
I have it there as well. Right underneath the recent convective burst.
So far I would agree with you.....satellite looks less impressive this morning....
Of corse, some models have shifted north…so we'll have some Northcasting too.
And the intensity models seem to have waned a bit, so we'll have a bit of
Weakcasting.
.LONG TERM...
OBVIOUSLY THE BIG TICKET ITEM FOR FRIDAY AND THE WEEKEND WILL BE
THE EVENTUAL EVOLUTION OF THE TROPICAL WAVE LOCATED NEAR THE
EASTERN TIP OF THE DOMINICAN REPUBLIC. THE NATIONAL HURRICANE
CENTER HAS RAISED THE CHANCE TO 70 PERCENT THAT A TROPICAL
DEPRESSION OR A TROPICAL STORM WILL FORM IN THE NEXT 48 HOURS.
WHILE THE MODELS ARE NOT USUALLY AS GOOD UNTIL A DEFINITE CENTER
IS FORMED THEY ARE IN FAIRLY GOOD AGREEMENT IN THE SHORT TERM. THE
00Z GFS RUNS THE SYSTEM OVER CENTRAL FLORIDA AND INTO THE EASTERN
GULF BEFORE LOSING IT WHILE THE ECMWF TAKES A RATHER WEAK SYSTEM
A LITTLE FURTHER SOUTH OVER EXTREME SOUTHERN FLORIDA OR THE
FLORIDA STRAITS BEFORE MOVING IT INTO THE EAST-CENTRAL GULF.
OVERALL...THE MODELS CONTINUE TO SHIFT BACK AND FORTH LATER IN THE
FORECAST BUT GENERALLY AGREE ON A TRACK ACROSS SOUTHERN FLORIDA
AND INTO THE EASTERN GULF. ON A POSITIVE NOTE...A FEW MODELS ARE
FORECASTING A SIGNIFICANT AMOUNT OF SHEAR OVER THE EASTERN GULF
IN 48-72 HOURS. IN THAT CASE...THERE MAY NOT BE MUCH OF A SYSTEM
TO SPEAK OF. FOR NOW HAVE RAISED POPS OVER THE WEEKEND TO 40 TO 50
PERCENT TO ACCOUNT FOR AT LEAST AN INCREASE IN TROPICAL MOISTURE.
Around 6:40 to 7:00 AM central.
Not sure I'd be laughing...
Also Tuesday, authorities found the body of a 14-year-old boy who drowned Sunday in a swollen river.
http://www.etaiwannews.com/etn/news_content.php?id=1324649&lang=eng_news
Here comes the sun.
A wide variety on the menu today. This should be fun to follow.
6Z GFS completely losses it at 72 hours...
ya'll have a goo one- zoomzoom zoom
NATIONAL WEATHER SERVICE MELBOURNE FL
429 AM EDT WED JUL 21 2010
THURS NIGHT-SAT...STILL SOME UNCERTAINTY LATE IN THE WEEK AS STRONG
TROPICAL WAVE CURRENTLY NEAR THE EASTERN DOMINICAN REPUBLIC IS
FORECAST TO SHIFT W/NW TOWARD SRN FLORIDA. MOST MODEL GUIDANCE
DEVELOPS THIS WAVE INTO A CLOSED LOW SYSTEM AND HAS IT APPROACHING
SRN FLORIDA BY EARLY MORNING FRIDAY. THE GFS IS FARTHER NORTH AND
SLIGHTLY SLOWER THAN THE NAM/UKMET/ECMWF WITH ITS TRACK OF THIS
SYSTEM SO USED A BLEND OF THE GFS/NAM FOR NOW WHICH ACTUALLY FITS
WELL WITH LATEST HPC POSITION. THIS BLEND TRACKS THE LOW CENTER OVER
SOUTH FLORIDA FRI AND NW INTO THE GULF FRI NIGHT/SAT. STRENGTH OF
THIS SYSTEM IS STILL DIFFICULT TO DETERMINE BUT FOR NOW WILL
MAINTAIN A WEAK TROPICAL LOW SCENARIO.
AS SYSTEM NEARS THE AREA LATE THURS NIGHT AND MOVES ACROSS FL
FRIDAY...A PERIOD OF HEAVY RAINFALL AND GUSTY WINDS WILL BE
POSSIBLE. HAVE INCREASED RAIN CHANCES TO 50% FOR FRIDAY AND THEN
AS SYSTEM MOVES PAST THE AREA INTO THE GULF...LINGERING MOISTURE
OVER THE AREA WILL KEEP RAIN CHANCES ELEVATED INTO THE WEEKEND
AROUND 40%. DUE TO THE INCREASED CLOUD COVER OVER THE REGION
FRI...HIGHS ONLY EXPECTED TO REACH THE UPPER 80S/LOW 90S BUT THEN
INCREASE BACK TO LOW/MID 90S INTO THE WEEKEND.
elsewhere as this system seems to be toast.
I swear, some of you need to learn to exercise a little bit of patience when watching these systems. 97L is not dead by a longshot.
Toast-caster.
The numbers don't lie. As of today......
July 21st, 2005.........July 21st, 2010
6-3-2..............1-1-0
The "F" storm was born today in 2005....
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