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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Quoting pipelines:
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.

really looks very well organized to me idk what ur seeing
Member Since: July 13, 2008 Posts: 6 Comments: 10796
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?
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1974. scott39
Quoting hunkerdown:
please, don't feed the animals...
Yea I hear ya, I should have known better that he would get my Sarcasm
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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.
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1972. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129090
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.



I think that tomorrow models will shift east slightly after the NOAA planes gather some upper air data. But nothing drastically... Im thinking strong Tropical storm/Minimal category 1 South-central florida
Member Since: Posts: Comments:
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
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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
Quoting scott39:
LOL, Jason your are crackin me up-- keep them coming
please, don't feed the animals...
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1967. gator23
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: Posts: Comments:
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: Posts: Comments:
Quoting Grothar:
Look at this!



Gulp. Holy sh$#
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1964. gator23
Quoting BaltOCane:
@post 1948: well played.

thank you
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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
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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
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Quoting wfyweather:


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

zack just keep on eye out just be ready for what comes to no
Member Since: July 13, 2008 Posts: 6 Comments: 10796
Looks like a LLC may have finally formed with a closed Low....just north of Puerto Rico at 19.2N 66.8W
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1959. scott39
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
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@post 1948: well played.
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1957. 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.

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1956. gator23
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?
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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
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: 695
1953. gator23
Quoting MiamiHurricanes09:
There is a ridge building back in that won't allow for much poleward motion.

maybe.
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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.
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1951. Grothar
Look at this!

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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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jasonisnotcoolman2010
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1948. gator23
Quoting jasoniscoolman2010x:
lots of dry here coming from the north where the upper low is

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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.
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1926:prepare for crow lol
Member Since: July 13, 2008 Posts: 6 Comments: 10796
1945. EricSFL
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...
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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?
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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.
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1942. Grothar
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.
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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.
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Quoting TampaSpin:


Very tight consesus of direction for this far out!

What does it have against MS?
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1939. scott39
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
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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.
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Quoting ackee:
Any one think NHC Will call this a TD AT 2am OR THEY WAIT On recon first

THEY WAIT On recon first
Member Since: July 4, 2010 Posts: 4 Comments: 965
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
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1934. Grothar
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.

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1933. gator23
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
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UNISYS View:


Puerto Rico NWS Radar:

Member Since: July 3, 2007 Posts: 0 Comments: 524
1931. gator23
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.
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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: Posts: Comments:
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.
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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.

Member Since: July 3, 2007 Posts: 0 Comments: 524

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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.