Dr. Jeff Masters' WunderBlog

97L continues to grow more organized; headed for Bahamas and Florida
Posted by: Dr. Jeff Masters, 7:07 PM GMT on July 20, 2010 +1
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
Categories: Hurricane
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1751. MiamiHurricanes09 1:56 AM GMT on July 21, 2010    
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1754. scott39 1:57 AM GMT on July 21, 2010    
Quoting StormW:


Better if you look at water vapor loop imagery

Thanks, The ULL-- I think--- is the only thing that is keeping 97L from developing rapidly, unless it interacts with the land mass of the ILands of course.
Member Since: June 13, 2009 Posts: 0 Comments: 6207
1755. Grothar 1:57 AM GMT on July 21, 2010    
Quoting Patrap:
Haiti getting Pounded near Port Au Prince

WunderMap®

Save or send this map to someone as you see it now. Link to current view.


Thanks, Pat. A lot of rain there and not moving much
Member Since: July 17, 2009 Posts: 56 Comments: 19487
1756. gator23 1:57 AM GMT on July 21, 2010    
Quoting Grothar:


Hope those ducks moved when people began evacuating!

It was Miami, no one evacuated. The one time we dont use our cars...
Member Since: August 26, 2008 Posts: 0 Comments: 1994
1757. aquak9 1:57 AM GMT on July 21, 2010    
Quoting FLdewey:
Jason do the snoz berries taste like snoz berries?


that's MY line, dewey...

and be nice to Jason, ya'll.
Member Since: August 13, 2005 Posts: 163 Comments: 24996
1759. CosmicEvents 1:58 AM GMT on July 21, 2010    
Quoting truecajun:
hi everyone. so looks like somewhere in FL for sure then into the GOM or is it still too early. what are the steering players? you the if it speeds up then this will happen if it slows down then this will happen yadayada
According to the experts and the models the track is high probability verifying the model lines...just follow the multiple consensus lines on the WU page. It's gonna' scoot right along with the southwest extent of the Bermuda high no matter how fast or slow it goes. And that high isn't moving(too much). The question on this one is intensity. It could be anything from a wave to a hurricane.
Member Since: August 3, 2005 Posts: 10 Comments: 5091
1760. Baybuddy 1:58 AM GMT on July 21, 2010    
Quoting stormpetrol:
Link
Look at this radar loop from PR The possible LLC center is closing off at 17.6N/68.5W where I stated earlier, It is removed from the heaviest convection and located further SW.


I thought i saw that too.(?)
Member Since: June 26, 2006 Posts: 0 Comments: 1115
1761. EtexJC 1:58 AM GMT on July 21, 2010    
Quoting FLdewey:


*record needle scratch


rotflmao
Member Since: August 17, 2007 Posts: 0 Comments: 218
1762. ChillinInTheKeys 1:59 AM GMT on July 21, 2010    
As far as I recall, no one ever evacuated in Miami until after Andrew.
Member Since: August 18, 2008 Posts: 0 Comments: 448
1764. tropics21 1:59 AM GMT on July 21, 2010    
Quoting wunderkidcayman:
so when will we see TS COLIN and TS DANEYLLE I have a feeling that these two will be huricanes or strong TS
Yep You are a Kid Wishing for storms one step at a time son one step at a time
Member Since: August 23, 2008 Posts: 0 Comments: 263
1765. AlexEmmett 1:59 AM GMT on July 21, 2010    
Quoting FLdewey:


*record needle scratch

wow wow wow people are really dumd somtimes
1767. HurricaneSwirl 2:01 AM GMT on July 21, 2010    
Quoting Hurricanes101:


exactly my point lol, incorrect information was given


Hopefully many people will follow this statement off of that tropical atlantic plot website with the spaghetti models for Google Earth:

DO NOT RELY ON ANY UNOFFICIAL SOURCES IN LIFE OR DEATH DECISIONS.

There's good stuff here, but I hope nobody makes decisions off of just a blog without knowing who to listen to lol. Hopefully unlikely.

Member Since: July 7, 2008 Posts: 2 Comments: 3237
1768. Baybuddy 2:01 AM GMT on July 21, 2010    
Storm W, if you aren't paid for your services, we need to take up a collection!
Member Since: June 26, 2006 Posts: 0 Comments: 1115
1773. Chicklit 2:02 AM GMT on July 21, 2010    
Holy Cow! That's lookin good finally Miami Hurricane! (#1751)
Member Since: July 11, 2006 Posts: 14 Comments: 10237
1774. xcool 2:03 AM GMT on July 21, 2010    
<<< lmao so hard
Member Since: September 26, 2009 Posts: 2 Comments: 15501
1776. MiamiHurricanes09 2:03 AM GMT on July 21, 2010    
Quoting weatherman12345:

stormW said as it moves it will weaken? any say in that?
Please clarify.
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1777. JRRP 2:04 AM GMT on July 21, 2010    
Member Since: August 16, 2007 Posts: 0 Comments: 4301
1778. xcool 2:04 AM GMT on July 21, 2010    


Member Since: September 26, 2009 Posts: 2 Comments: 15501
1779. scott39 2:05 AM GMT on July 21, 2010    
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: 6207
1780. weathers4me 2:05 AM GMT on July 21, 2010    
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.
Member Since: May 24, 2007 Posts: 0 Comments: 112
1781. MiamiHurricanes09 2:05 AM GMT on July 21, 2010    
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: 129 Comments: 19976
1782. Skyepony (Mod) 2:05 AM GMT on July 21, 2010    
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..
Member Since: August 10, 2005 Posts: 144 Comments: 29238
1786. stormhank 2:06 AM GMT on July 21, 2010    
If 97L/td or ts gets in the GOM what portion of gulf coast would most likely be affected??
Member Since: September 8, 2005 Posts: 0 Comments: 1375
1787. SouthDadeFish 2:06 AM GMT on July 21, 2010    
Quoting ChillinInTheKeys:
As far as I recall, no one ever evacuated in Miami until after Andrew.
My family evacuated for Andrew. Good thing too.
Member Since: August 12, 2007 Posts: 11 Comments: 2413
1788. HurricaneSwirl 2:06 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:


Impressive. Can clearly see the center pretty much right where the 925 vort max is.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
1789. reedzone 2:07 AM GMT on July 21, 2010    
CIMMS shear map shows an anticyclone forming over 97L, shear will NOT effect it anymore.
Member Since: July 1, 2008 Posts: 13 Comments: 7247
1790. scott39 2:07 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
What the upper low?
yes
Member Since: June 13, 2009 Posts: 0 Comments: 6207
1791. Chicklit 2:07 AM GMT on July 21, 2010    
OUCH, Skyepony.
97L needs to lift on outta there.
Member Since: July 11, 2006 Posts: 14 Comments: 10237
1792. FranAteMyRoof96 2:08 AM GMT on July 21, 2010    
whatever happened to FranAteMyRoof96?
ohhh here i am!

hello all. thanks for the info!
annnnd back to lurking.
Member Since: July 3, 2008 Posts: 0 Comments: 189
1794. earthlydragonfly 2:09 AM GMT on July 21, 2010    
Quoting gator23:
FTW

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

Jk
Member Since: July 1, 2005 Posts: 10 Comments: 1649
1795. Chicklit 2:09 AM GMT on July 21, 2010    
Member Since: July 11, 2006 Posts: 14 Comments: 10237
1796. wunderkidcayman 2:10 AM GMT on July 21, 2010    
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
Member Since: June 13, 2009 Posts: 2 Comments: 5381
1797. centex 2:10 AM GMT on July 21, 2010    
Still looks like land needs to be in discussion.

Still looks like land needs to be in discussion.
Member Since: August 10, 2007 Posts: 0 Comments: 2856
1798. texwarhawk 2:10 AM GMT on July 21, 2010    
is it just me or have the steering patterns shifted more westerly
Member Since: July 7, 2010 Posts: 4 Comments: 202
1799. Grothar 2:10 AM GMT on July 21, 2010    
Quoting ChillinInTheKeys:
As far as I recall, no one ever evacuated in Miami until after Andrew.


Weren't around for David in 1979?
Member Since: July 17, 2009 Posts: 56 Comments: 19487
1800. TampaSpin 2:10 AM GMT on July 21, 2010    
Evening everyone! Looks like a TD coming within the next 12 hours if not before!
Member Since: September 2, 2007 Posts: 175 Comments: 19747
1801. MiamiHurricanes09 2:11 AM GMT on July 21, 2010    
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: 129 Comments: 19976

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About JeffMasters
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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