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
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1901. CaneWarning 2:39 AM GMT on July 21, 2010    
Quoting Skyepony:
ASCAT was a total miss.

CaneWarning~ if you clicked on the image it would take you to the site.

& for the one not buying it..it's the Offical forecast..just passing it along..


Thank you.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1902. txsweetpea 2:39 AM GMT on July 21, 2010    
Quoting TampaSpin:


Hello....sorry started watching some of the BAseball game...dang! Got a storm we gotta watch for sure.



yes definitely!
Member Since: June 7, 2010 Posts: 0 Comments: 546
1903. truecajun 2:39 AM GMT on July 21, 2010    
Quoting scott39:
LOL, " " doesnt always keep us safe from blasting.j/k


i know. i'm scared to say anything too definitive on here. some people are ruthless, so i use a lot of question marks and " "

it makes me feel "safe" - there i go again :)
Member Since: August 24, 2006 Posts: 0 Comments: 1848
1905. ChillinInTheKeys 2:40 AM GMT on July 21, 2010    
Good Blog entry. I was always curious, Is CCHS Cooper City High School?
Member Since: August 18, 2008 Posts: 0 Comments: 448
1906. oddspeed 2:40 AM GMT on July 21, 2010    
last 4 hours PR radar showing massive rains offshore
Member Since: September 4, 2007 Posts: 0 Comments: 225
1907. xcool 2:40 AM GMT on July 21, 2010    
td come.imo
Member Since: September 26, 2009 Posts: 2 Comments: 15503
1908. CaneWarning 2:40 AM GMT on July 21, 2010    
Quoting StSimonsIslandGAGuy:
I still wonder if 97L will be like Erin in 1995--track and time of year are similar.

Although I do doubt 97L will be a hurricane before hitting FL. But ya never know for sure...


How 'bout the election?

97L might be a TD soon I think.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1909. Chicklit 2:40 AM GMT on July 21, 2010    
Just want it the heck out of Haiti.
They've got troubles enough.
Goodnight.
Member Since: July 11, 2006 Posts: 14 Comments: 10255
1910. Grothar 2:41 AM GMT on July 21, 2010    
Quoting TampaSpin:
Looks like the blog is completely filled with negative comments and non-sense as usuall when things get active....nothing knew!


I see someone is in a good mood. How you doing T? We were very technical a while back, but nothing new yet. Waiting till the 11 PM advisory, unless it is already out.
Member Since: July 17, 2009 Posts: 57 Comments: 19555
1911. AlexEmmett 2:41 AM GMT on July 21, 2010    
Quoting ackee:
Any one think NHC Will call this a TD AT 2am OR THEY WAIT On recon first

i give it a 40% chance 90% chance tommarow
1912. Patrap 2:41 AM GMT on July 21, 2010    
41 Years ago @ 10:56 Pm EST

20 July 1969



Member Since: July 3, 2005 Posts: 372 Comments: 111635
1913. Orcasystems 2:41 AM GMT on July 21, 2010    
Pick a track.. any track :)



AOI
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1914. TampaSpin 2:42 AM GMT on July 21, 2010    


Very tight consesus of direction for this far out!
Member Since: September 2, 2007 Posts: 175 Comments: 19747
1915. bappit 2:42 AM GMT on July 21, 2010    
Quoting Chicklit:
I've got perspective cuz I have hardly been here, and can tell you, 97L has scarcely moved since last night.

It's, ummm, back building. The discussion says the waved moved on to Cuba leaving a surface trough with strong convergence. Surface convergence extends south from the Virgin Islands on the CIMSS map.
Member Since: May 18, 2006 Posts: 3 Comments: 4389
1916. CanesfanatUT 2:42 AM GMT on July 21, 2010    
Quoting gator23:
FTW



^^^Me before gear.

<--- Me after gear.
Member Since: September 3, 2007 Posts: 0 Comments: 459
1917. AlexEmmett 2:43 AM GMT on July 21, 2010    
orca, wth do the models have against florida and the gulf
1918. gator23 2:43 AM GMT on July 21, 2010    
Quoting zoomiami:
someone said the other night that hurricanes in So Florida are over rated, they don't happen that often.

I've been through so many hurricanes, I don't even know their names. Just because only one of them was a cat 5 that destroyed an entire area does not make it a calm place to be.

I've been here since 1983


1)They happen more often down there
2) They are "felt" for a longer period of time because they generally dont weaken as much when crossing South Florida as is the case everywhere else, in other words the second half of the storm can be as storng as the first half.

So whoever said that doesnt know what they are talking about.
Member Since: August 26, 2008 Posts: 0 Comments: 1994
1919. CosmicEvents 2:43 AM GMT on July 21, 2010    
Quoting Skyepony:
Model error after 24hrs in nm..

AEMN 84.3
OFCL 93.9
BAMD 115.4
LGEM 150.4
BAMM 160.8
XTRP 179.7
LBAR 188.1
HWRF 238.5
BAMS 297.6
That's a great point to keep in mind for ALL the storms that we have in a season(or a few seasons)....but isn't each cyclone unique? You know much more than I, and most everyone. Is there something that you see in the synoptic set-up with this particular cyclone that leads you to think we'll see a 150NM error in this case? In 24 hours....or even in 96 hours. I'd be really interested to hear some informed case being made for a move south of Cuba or North of Daytona.
Member Since: August 3, 2005 Posts: 10 Comments: 5099
1920. bohonkweatherman 2:43 AM GMT on July 21, 2010    
I think there is a decent chance this goes straight to tropical storm Bonnie, it could be a minimum hurricane before reaching Florida and who knows where she moves after that.
Member Since: July 5, 2009 Posts: 0 Comments: 1348
1921. TheDawnAwakening2 2:44 AM GMT on July 21, 2010    
convection over Haiti shows signs of weakening, likely do to the loss of instability in the atmosphere, and fueled by wind shear right now. This should weaken as the night wears on. This was not caused by 97L directly.
Member Since: December 4, 2009 Posts: 24 Comments: 251
1922. Orcasystems 2:44 AM GMT on July 21, 2010    
Quoting AlexEmmett:
orca, wth do the models have against florida and the gulf

DIIK?
I would assume they are tired of pointing at Texas... wait 48 hours.
Member Since: October 1, 2007 Posts: 77 Comments: 26077
1924. TampaSpin 2:45 AM GMT on July 21, 2010    
Quoting Grothar:


I see someone is in a good mood. How you doing T? We were very technical a while back, but nothing new yet. Waiting till the 11 PM advisory, unless it is already out.


Hey Bro....looking at the most recent loops look rather YIKES !!!!
Member Since: September 2, 2007 Posts: 175 Comments: 19747
1925. AlexEmmett 2:45 AM GMT on July 21, 2010    
Quoting Orcasystems:

DIIK?
I would assume they are tired of pointing at Texas... wait 48 hours.

lol
1927. bappit 2:46 AM GMT on July 21, 2010    
The dry air took out the leading convection yesterday while convection increased on the trailing side under the little anticyclone that was ketchin' up.

Today that small anticyclone stands transformed into a mighty shield of anticyclonicity pressing against the forces of the evil King TUTT and his dry air minions.
Member Since: May 18, 2006 Posts: 3 Comments: 4389
1928. TropicalNonsense 2:46 AM GMT on July 21, 2010    
Quoting CosmicEvents:
What's the point of bringing up cyclones from times past that are now dead if you only look at landfall point and disregard the track?
.
.
I need a break from this place. sigh


similar synoptic steering patterns were in place back then
and those particular storms also made landfall in central
Florida.

Why is that hard to comprehend? it was just a
steering pattern setup that reminds many of this
current scenario.

Studying past storms and past track histories for comparison
is what all good stormchaser and Mets do.

Even Dr. Masters will mention past storm tracks sometimes.

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1929. MiamiHurricanes09 2:46 AM GMT on July 21, 2010    
Quoting bohonkweatherman:
I think there is a decent chance this goes straight to tropical storm Bonnie, it could be a minimum hurricane before reaching Florida and who knows where she moves after that.
I agree. Shear should be low along with a moist environment to work with. And as you know SSTs and OHC is boiling by the Bahamas, especially by the Gulf Stream. I think before landfall in SEFL that 97L could reach a minimal category 1 hurricane.
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1930. CoffinWood 2:46 AM GMT on July 21, 2010    
Quoting Grothar:


My mother's family moved to Miami in 1923!
Although I spent a lot of time in Europe, the first Hurricane I remember was 1948 and a lot since. We used to get hit in South Florida all the time and then in the mid-60's is stopped until David and then Andrew in 1992. Looks like we are back in the old pattern again.

P.S. I am very old, just ask anyone on the blog. lOL


I find you both hysterical and historical. If you're ever in the mood, it would be interesting to hear about some of the hurricanes you and your family rode out (or evacuated for).
Member Since: June 19, 2010 Posts: 0 Comments: 113
1931. gator23 2:47 AM GMT on July 21, 2010    
Quoting TropicalNonsense:


similar synoptic steering patterns were in place back then
and those particular storms also made landfall in central
Florida.

Why is that hard to comprehend? it was just a
steering pattern setup that reminds many of this
current scenario.

Studying past storms and past track histories for comparison
is what all good stormchaser and Mets do.

Even Dr. Masters will mention past storm tracks sometimes.


I agree with you. We analyze analog years here why not analog storms.
Member Since: August 26, 2008 Posts: 0 Comments: 1994
1932. TropicalNonsense 2:47 AM GMT on July 21, 2010    
UNISYS View:


Puerto Rico NWS Radar:

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1933. gator23 2:48 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
I agree. Shear should be low along with a moist environment to work with. And as you know SSTs and OHC is boiling by the Bahamas, especially by the Gulf Stream. I think before landfall in SEFL that 97L could reach a minimal category 1 hurricane.

If the center does reform more east and it does become a Hurricane a more northly track may happen sparing parts of South Florida, maybe
Member Since: August 26, 2008 Posts: 0 Comments: 1994
1934. Grothar 2:48 AM GMT on July 21, 2010    
Quoting TampaSpin:


Hey Bro....looking at the most recent loops look rather YIKES !!!!


Yo! Could be right, look how it is building convection near the center.

Member Since: July 17, 2009 Posts: 57 Comments: 19555
1935. TampaSpin 2:48 AM GMT on July 21, 2010    


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1936. AllyBama 2:48 AM GMT on July 21, 2010    
Pick a track.. any track :)

NOT the one that leads to my house! - YIKES!
what happened to TX and the east coast of FL?..lol
Member Since: August 3, 2006 Posts: 131 Comments: 20499
1938. extreme236 2:48 AM GMT on July 21, 2010    
Quoting jasoniscoolman2010x:
lots of dry here coming from the north where the upper low is


Dry air isn't gonna stop this from developing most likely.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1939. scott39 2:49 AM GMT on July 21, 2010    
Quoting jasoniscoolman2010x:
lots of dry here coming from the north where the upper low is
LOL, Jason your are crackin me up-- keep them coming
Member Since: June 13, 2009 Posts: 0 Comments: 6207
1940. BiloxiIsle 2:49 AM GMT on July 21, 2010    
Quoting TampaSpin:


Very tight consesus of direction for this far out!

What does it have against MS?
Member Since: May 11, 2008 Posts: 0 Comments: 133
1941. MiamiHurricanes09 2:49 AM GMT on July 21, 2010    
Quoting gator23:

If the center does reform more east and it does become a Hurricane a more northly track may happen sparing parts of South Florida, maybe
There is a ridge building back in that won't allow for much poleward motion.
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1942. Grothar 2:50 AM GMT on July 21, 2010    
Quoting CoffinWood:


I find you both hysterical and historical. If you're ever in the mood, it would be interesting to hear about some of the hurricanes you and your family rode out (or evacuated for).


Thanks, sense of humor is the last thing to go, unfortunately. Anytime.
Member Since: July 17, 2009 Posts: 57 Comments: 19555
1943. AllStar17 2:50 AM GMT on July 21, 2010    
Quoting extreme236:


Dry air isn't gonna stop this from developing most likely.


I'd just ignore his posts. Earlier he mocked up a fake NHC TWO, and is surprisingly still around and not banned.
Member Since: June 29, 2009 Posts: 13 Comments: 5135
1944. wfyweather 2:51 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
I agree. Shear should be low along with a moist environment to work with. And as you know SSTs and OHC is boiling by the Bahamas, especially by the Gulf Stream. I think before landfall in SEFL that 97L could reach a minimal category 1 hurricane.


im goin to no on sat and leavin on wed.... would u be worried if u were me?
Member Since: July 12, 2008 Posts: 11 Comments: 422
1945. EricSFL 2:51 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
I agree. Shear should be low along with a moist environment to work with. And as you know SSTs and OHC is boiling by the Bahamas, especially by the Gulf Stream. I think before landfall in SEFL that 97L could reach a minimal category 1 hurricane.


Katrina-style...
Member Since: May 26, 2010 Posts: 0 Comments: 759
1947. MiamiHurricanes09 2:51 AM GMT on July 21, 2010    
Quoting extreme236:


Dry air isn't gonna stop this from developing most likely.
Water vapor loops suggest that dry air is diminishing as 97L's large size is moistening up the environment.
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1948. gator23 2:52 AM GMT on July 21, 2010    
Quoting jasoniscoolman2010x:
lots of dry here coming from the north where the upper low is

Member Since: August 26, 2008 Posts: 0 Comments: 1994
1949. extreme236 2:52 AM GMT on July 21, 2010    
jasonisnotcoolman2010
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1950. hunkerdown 2:52 AM GMT on July 21, 2010    
Quoting StSimonsIslandGAGuy:
I still wonder if 97L will be like Erin in 1995--track and time of year are similar.

Although I do doubt 97L will be a hurricane before hitting FL. But ya never know for sure...
that was a vero landfall, don;t think she'll sneak that far north.
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1951. Grothar 2:52 AM GMT on July 21, 2010    
Look at this!

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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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