97L continues to grow more organized; headed for Bahamas and Florida

By: Dr. Jeff Masters , 7:07 PM GMT on July 20, 2010

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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

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hey aquak i got battery installed today and Earthlydragonfly or superfly caster weather station is back in business
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Quoting Skyepony:
OFCL Wind forecast green is weak Tropical Storm. Tan Strong TS


Post like that have no relevance. Sorry but just not buying that.
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Is 97L have the possibility to become a hurricane before approaching florida??
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1825. xcool
OFCL track anyway
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1824. gator23
Quoting CaneWarning:


Where did you find this map? If I look at it correctly, Tampa could get TS winds?

seems like the swath is too big.
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Just did a blog on 97L.
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Quoting MiamiHurricanes09:
Look at the outflow in the eastern and southern quadrant.


Yep, the anticyclone that's forming right now is pushing the wind shear north, like a shield. I expect TD3 by tomorrow afternoon if not the morning.
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1821. geepy86
1799 I was around for david and I did not evac. It was quite a storm. Just some minor damage. How many others can say they were around for David?
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Quoting Skyepony:
OFCL Wind forecast green is weak Tropical Storm. Tan Strong TS
and light blue, tropical breezes ?
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Quoting Skyepony:
OFCL Wind forecast green is weak Tropical Storm. Tan Strong TS


Uh-oh. Here in Macon GA we are under Blue for Subtropical Storm! Better get the shutters out XD
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1817. scott39
Quoting jasoniscoolman2010x:
some dry air will effect it.
Dry air Dry air dry air dry air --whew ---dry air dry air......
Member Since: June 13, 2009 Posts: 0 Comments: 6914
Quoting Skyepony:
OFCL Wind forecast green is weak Tropical Storm. Tan Strong TS


Where did you find this map? If I look at it correctly, Tampa could get TS winds?
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will people stop asking the same questions over and over and over the answers are in the posts all you got to do is read them because this is getting on my nerves
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Quoting reedzone:
CIMMS shear map shows an anticyclone forming over 97L, shear will NOT effect it anymore.
Look at the outflow in the eastern and southern quadrant.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
Speaking of ants (lol), there has been a huge increase of ants and ant piles here in Miami, like I swear I have not seen so many ants since 2005. Now that I see all these models pointing to south Florida I'm just thinking to myself..."Damn, ants can forecast tropical activity 2 weeks in advance." LOL.


Yeah, too bad Amdro doesn't work on tropical activity......
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via WUmail:

FROM: Acere25


TO: CaicosRetiredSailor
DATE: 2010-07-20 21:26:10 (9:26 PM EDT)
SUBJECT: :(
Stay safe, plz! I'll be praying for you guys down here. Hey, are the storm's squall lines, producing any winds?


==================
Acere25
Brand new account

Urban Dictionary: acere

It's the Cuban, not Miami, way to say "bro"
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1809. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting TampaSpin:
Evening everyone! Looks like a TD coming within the next 12 hours if not before!



Hey Tampa!
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1807. Skyepony (Mod)
OFCL Wind forecast green is weak Tropical Storm. Tan Strong TS
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1806. scott39
Quoting weathers4me:
Not sure what graphic some of you are looking at but looking at the last sat loop this disturbance looks quite impressive. Take a look at the outflow and banding developing. D max will really be interesting tonight.
The ULL needs to move for 97L to really get going.
Member Since: June 13, 2009 Posts: 0 Comments: 6914
I don't remember anyone leaving. Was on 189th st. Maybe blew 40.
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Haiti is getting slammed.
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Quoting weatherman12345:

POST (1685)
Oh the upper low. Looking at the GFS 18z upper air graphics I think that the upper low will be inland in 48 hours and weak. Also, 97L is beginning to develop anticyclonic flow. At the moment I would suspect that shear shouldn't be a problem for 97L in its intensification process.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Evening everyone! Looks like a TD coming within the next 12 hours if not before!
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1799. Grothar
Quoting ChillinInTheKeys:
As far as I recall, no one ever evacuated in Miami until after Andrew.


Weren't around for David in 1979?
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is it just me or have the steering patterns shifted more westerly
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1797. centex
Still looks like land needs to be in discussion.

Still looks like land needs to be in discussion.
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I AM NOT A PERSON THAT DOES THAT TROPICS21 I NEVER DO AND HOW DARE YOU

anyway guys I and going to bed this hotel in nice in Trinidad see you all 2mrrow
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Quoting gator23:
FTW

<<<<<<<<----- Opens door. Peeks inside... "OMG" turns slowly closes door..

Jk
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whatever happened to FranAteMyRoof96?
ohhh here i am!

hello all. thanks for the info!
annnnd back to lurking.
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OUCH, Skyepony.
97L needs to lift on outta there.
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1790. scott39
Quoting MiamiHurricanes09:
What the upper low?
yes
Member Since: June 13, 2009 Posts: 0 Comments: 6914
CIMMS shear map shows an anticyclone forming over 97L, shear will NOT effect it anymore.
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Quoting MiamiHurricanes09:


Impressive. Can clearly see the center pretty much right where the 925 vort max is.
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Quoting ChillinInTheKeys:
As far as I recall, no one ever evacuated in Miami until after Andrew.
My family evacuated for Andrew. Good thing too.
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If 97L/td or ts gets in the GOM what portion of gulf coast would most likely be affected??
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1782. Skyepony (Mod)
In the last 3 hrs, parts of the earthquake affected part of Haiti has had ~30mm of rain (1.18in).


East side of PR has had atleast 5 1/2 inch in the last 12 hrs..
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Quoting scott39:
He said it would be over the Bahamas in 48 hours N of 97L
What the upper low?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Not sure what graphic some of you are looking at but looking at the last sat loop this disturbance looks quite impressive. Take a look at the outflow and banding developing. D max will really be interesting tonight.
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1779. scott39
Quoting MiamiHurricanes09:
Please clarify.
He said it would be over the Bahamas in 48 hours N of 97L
Member Since: June 13, 2009 Posts: 0 Comments: 6914
1778. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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