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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1951. Grothar 2:52 AM GMT on July 21, 2010    
Look at this!

Member Since: July 17, 2009 Posts: 58 Comments: 19672
1952. MiamiHurricanes09 2:53 AM GMT on July 21, 2010    
Quoting wfyweather:


im goin to no on sat and leavin on wed.... would u be worried if u were me?
I'm in Miami and not planning on leaving. At this point I'm just stocking up on necessities but nothing major.
Member Since: September 2, 2009 Posts: 129 Comments: 20002
1953. gator23 2:53 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
There is a ridge building back in that won't allow for much poleward motion.

maybe.
Member Since: August 26, 2008 Posts: 0 Comments: 2030
1954. ChillinInTheKeys 2:53 AM GMT on July 21, 2010    
Seems this storm is really enjoying its stay in PR. The blob as a whole (I said "as a whole") seems to be stationary.
Member Since: August 18, 2008 Posts: 0 Comments: 462
1955. TropicalNonsense 2:53 AM GMT on July 21, 2010    
Quoting gator23:

I agree with you. We analyze analog years here why not analog storms.


yes. i am glad someone understands. wow there is alot of criticism
on this blog today. everyone is whining i just dont get it.

maybe a potential [Florida] storm has got many on edge or something.

who knows it may not even develop but i am thinking
it is worth watching very carefully!
Member Since: July 3, 2007 Posts: 0 Comments: 524
1956. gator23 2:53 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
I'm in Miami and not planning on leaving. At this point I'm just stocking up on necessities but nothing major.

did you get your supplies form publix, what do you buy?
Member Since: August 26, 2008 Posts: 0 Comments: 2030
1957. Grothar 2:54 AM GMT on July 21, 2010    
Rare to see the models so clustered. May have to change the name of Cone of Uncertainty to the Cone of Almost Certain if this keeps up.

Member Since: July 17, 2009 Posts: 58 Comments: 19672
1958. BaltOCane 2:54 AM GMT on July 21, 2010    
@post 1948: well played.
Member Since: May 19, 2009 Posts: 0 Comments: 411
1959. scott39 2:54 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
Water vapor loops suggest that dry air is diminishing as 97L's large size is moistening up the environment.
Look at this Jason. Please
Member Since: June 13, 2009 Posts: 0 Comments: 6221
1960. TampaSpin 2:54 AM GMT on July 21, 2010    
Looks like a LLC may have finally formed with a closed Low....just north of Puerto Rico at 19.2N 66.8W
Member Since: September 2, 2007 Posts: 176 Comments: 19767
1962. wfyweather 2:54 AM GMT on July 21, 2010    
Quoting MiamiHurricanes09:
I'm in Miami and not planning on leaving. At this point I'm just stocking up on necessities but nothing major.


Yeah.... guess ill just be keepin tabs on the situation and if it looks like a big cane for N.O ill get out of there. lol
Member Since: July 12, 2008 Posts: 11 Comments: 422
1963. truecajun 2:55 AM GMT on July 21, 2010    
Quoting wfyweather:


im goin to no on sat and leavin on wed.... would u be worried if u were me?


we'll know more as it progresses, but it seems 6 or 7 days out IF it would make a LA MS landfall, but of course it's still too early to say
Member Since: August 24, 2006 Posts: 0 Comments: 1848
1964. gator23 2:55 AM GMT on July 21, 2010    
Quoting BaltOCane:
@post 1948: well played.

thank you
Member Since: August 26, 2008 Posts: 0 Comments: 2030
1965. mcluvincane 2:55 AM GMT on July 21, 2010    
Quoting Grothar:
Look at this!



Gulp. Holy sh$#
Member Since: June 2, 2010 Posts: 0 Comments: 1315
1966. pipelines 2:55 AM GMT on July 21, 2010    
Everyone take a deep breath, the circulation in 97L is still very poorly defined. Until it consolidates, this thing isn't going anywhere fast in terms of intensification. It could take 24 hours or more before this happens and the real show begins.
Member Since: July 10, 2008 Posts: 0 Comments: 222
1967. gator23 2:56 AM GMT on July 21, 2010    
Quoting Grothar:
Rare to see the models so clustered. May have to change the name of Cone of Uncertainty to the Cone of Almost Certain if this keeps up.



still the more reliable models are north of the consensus
Member Since: August 26, 2008 Posts: 0 Comments: 2030
1968. hunkerdown 2:56 AM GMT on July 21, 2010    
Quoting scott39:
LOL, Jason your are crackin me up-- keep them coming
please, don't feed the animals...
Member Since: August 15, 2008 Posts: 0 Comments: 2514
1969. SeniorPoppy 2:57 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.


I just don't like how things are currently unfolding. The anticyclonic flow currently being established is not a good sign. Dry air is also not much of a factor right now.
Member Since: August 4, 2009 Posts: 0 Comments: 497
1970. AlexEmmett 2:57 AM GMT on July 21, 2010    
Quoting TampaSpin:
Looks like a LLC have have finally formed with a closed Low....just north of Puerto Rico at 19.2N 66.8W

if thats the case we could get a renumber and notacoolman is wrong again
1972. Patrap 2:58 AM GMT on July 21, 2010    
Member Since: July 3, 2005 Posts: 377 Comments: 112972
1973. CyclonicVoyage 2:58 AM GMT on July 21, 2010    
Quoting btwntx08:

though it showed it being a hurricane in 6 hrs which was wrong lol


HWRF not wrong for another 6 hours. Intensity is always sketchy with the HWRF. Rather remarkable if the track and timing pan out.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
1974. scott39 2:58 AM GMT on July 21, 2010    
Quoting hunkerdown:
please, don't feed the animals...
Yea I hear ya, I should have known better that he would get my Sarcasm
Member Since: June 13, 2009 Posts: 0 Comments: 6221
1975. earthlydragonfly 2:58 AM GMT on July 21, 2010    
Member Since: July 1, 2005 Posts: 10 Comments: 1653
1977. KoritheMan 2:58 AM GMT on July 21, 2010    
Quoting TampaSpin:
Looks like a LLC may have finally formed with a closed Low....just north of Puerto Rico at 19.2N 66.8W


I'm not seeing this. Could you post some observations?
Member Since: March 7, 2007 Posts: 421 Comments: 15643
1979. hunkerdown 2:59 AM GMT on July 21, 2010    
Quoting Grothar:
Look at this!

WOW

Member Since: August 15, 2008 Posts: 0 Comments: 2514
1980. MiamiHurricanes09 2:59 AM GMT on July 21, 2010    
Quoting SeniorPoppy:


I just don't like how things are currently unfolding. The anticyclonic flow currently being established is not a good sign. Dry air is also not much of a factor right now.
Same here. I'm watching this closely.
Member Since: September 2, 2009 Posts: 129 Comments: 20002
1981. Patrap 2:59 AM GMT on July 21, 2010    





Member Since: July 3, 2005 Posts: 377 Comments: 112972
1982. 7544 2:59 AM GMT on July 21, 2010    
97l is looking good at this hour 11pm new convction forming in the middle lots of moisture to work with dmax may turn this to td3 or even ts bonnie imo we might wake up to a ts tomorow
Member Since: May 6, 2007 Posts: 0 Comments: 6020
1984. truecajun 2:59 AM GMT on July 21, 2010    
this is not a huge deal, but we have a swimming party planned for my niece, daughter, and husband's birthday on saturday at my in laws neighborhood pool. no matter which track she takes, we'll most likely get rained out all saturday in southeast LA right?

i'd like to know because if so, then i'll have to host everyone at my house.
Member Since: August 24, 2006 Posts: 0 Comments: 1848
1985. CyclonicVoyage 2:59 AM GMT on July 21, 2010    
Quoting Grothar:
Rare to see the models so clustered. May have to change the name of Cone of Uncertainty to the Cone of Almost Certain if this keeps up.



Almost certainly wrong if the center ends up north of PR. Stay tuned folks, we're in a game of find the LLC.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
1986. Patrap 3:00 AM GMT on July 21, 2010    
Member Since: July 3, 2005 Posts: 377 Comments: 112972
1987. Orcasystems 3:00 AM GMT on July 21, 2010    
Quoting StSimonsIslandGAGuy:
What I like least about the blog is how this weekend, people will be saying "I had 97L/Bonnie nailed and YOU (or blogger X) had it wrong."

Almost makes me want to wishcast it to Georgia just to be outside the cone and take a chance on an out-there guess being right.


Member Since: October 1, 2007 Posts: 77 Comments: 26110
1988. TampaSpin 3:00 AM GMT on July 21, 2010    


Here is every model known to mankind!!
Member Since: September 2, 2007 Posts: 176 Comments: 19767
1989. BaltOCane 3:00 AM GMT on July 21, 2010    
MH09 - you were pretty dead on with how Alex would intesify to a Cat2 right before landfall, so I'm gonna go with you on this one
I agree with you.
Member Since: May 19, 2009 Posts: 0 Comments: 411
1990. MiamiHurricanes09 3:01 AM GMT on July 21, 2010    
Quoting KoritheMan:


I'm not seeing this. Could you post some observations?
Me either, I do believe that there is an area of low pressure near 19.8N˚ and 68.5˚W but it remains open.
Member Since: September 2, 2009 Posts: 129 Comments: 20002
1991. gator23 3:01 AM GMT on July 21, 2010    
Quoting BaltOCane:
MH09 - you were pretty dead on with how Alex would intesify to a Cat2 right before landfall, so I'm gonna go with you on this one
I agree with you.

he called for landfall in texas. not that dead on. Brickell is good at what he does though
Member Since: August 26, 2008 Posts: 0 Comments: 2030
1992. JLPR2 3:01 AM GMT on July 21, 2010    
I'm not linking the direction in which that convection is moving, I'm located at the easternmost black cross.
Member Since: September 4, 2007 Posts: 7 Comments: 7528
1993. 7544 3:02 AM GMT on July 21, 2010    
hey tampa you benn right on the money in past years so i am listing to waht you say good call tho
Member Since: May 6, 2007 Posts: 0 Comments: 6020
1994. AussieStorm 3:02 AM GMT on July 21, 2010    
Member Since: September 30, 2007 Posts: 5 Comments: 13787
1995. all4hurricanes 3:02 AM GMT on July 21, 2010    
the models were all in agreement a couple days ago that this would hit Cuba than TX I'm not sold on a South Fl than LA landfall
I'm thinking Bonnie
Good night everyone
Member Since: March 29, 2008 Posts: 0 Comments: 2234
1996. LADobeLady 3:02 AM GMT on July 21, 2010    
Quoting TampaSpin:


Here is every model known to mankind!!


That is one big plate of spaghetti.
Member Since: July 29, 2005 Posts: 21 Comments: 794
1997. Drakoen 3:02 AM GMT on July 21, 2010    
Member Since: October 28, 2006 Posts: 57 Comments: 29012
1998. EricSFL 3:03 AM GMT on July 21, 2010    
I think Bolero had an over-excitement attack and he is no longer posting here.
Member Since: May 26, 2010 Posts: 0 Comments: 759
2000. zoomiami 3:03 AM GMT on July 21, 2010    
I think it would be better to wait until the comments are made before we start complaining about them. Its kind of like having the argument by yourself.
Member Since: August 13, 2007 Posts: 10 Comments: 4071

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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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