97L gets disrupted by Hispaniola

By: Dr. Jeff Masters , 12:53 PM GMT on July 21, 2010

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A tropical wave (Invest 97L) near the north coast of Hispaniola has been disrupted by interaction with the island, plus the effects of moderate wind shear of 10 - 20 knots. The storm is no longer a threat to develop into a tropical depression today, and the Hurricane Hunter flight that was scheduled for today has been postponed until Thursday. The disturbance has brought heavy rains of 8+ inches to Culebra, Vieques, the Virgin Islands, and some of the northern Lesser Antilles Islands. Wunderblogger Weather456 reported that the power was knocked out on the island of St. Kitts for about 24 hours, due to the intense lightning associated with 97L. All of Puerto Rico and the Virgin Islands are under flash flood watches today.

Satellite images of 97L show a relatively meager number of heavy thunderstorms that are not well-organized. The curved bands to the north and east of the center have disappeared, and there is no evidence of low-level spiral banding or of a surface circulation. Surface observations over the northern Dominican Republic show only light winds, with no westerly winds indicating that a surface circulation is forming. Long-range radar loops from San Juan show a much reduced amount of thunderstorm activity.


Figure 1. Total radar-estimate rainfall for 97L.

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 to Haiti on today and Thursday. Heavy rains from 97L will affect eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas Thursday, and South and Central Florida can expect heavy rains to arrive Thursday night or Friday morning. The latest suite of model runs from 2am EDT this morning (6Z) foresee 97L making landfall on the Florida coast somewhere between Miami and Cape Canaveral on Friday, then continuing into the Gulf of Mexico on Saturday. Only the Canadian model foresees a threat to Texas, and the other models predict a second landfall between eastern Louisiana and the Florida Panhandle.

Intensity Forecast for 97L
The primary detriment to development of 97L today will be its close proximity to the landmass of Hispaniola. Once the storm pulls away from the island tonight, 97L has a better chance of development. Also hindering development over the next two days will 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. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next three days, which should allow for some steady development of 97L on Thursday and Friday before it reaches Florida. NHC is giving 97L a 60% chance of developing into a tropical depression by Friday, 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 before 97L reaches Florida is unlikely, due to the storm's current state of disorganization and the dry air over the Bahamas. It's very unlikely that 97L has time to organize into a hurricane before hitting Florida. I put the odds of 97L making it to hurricane strength before reaching Florida at 5%, 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 water in the Gulf, which is very uncertain. The environment in the Gulf of Mexico should be favorable for intensification, if passage over Florida does not disrupt the storm too much.

I'll have a new post Thursday morning, or earlier if there's a major change to 97L.

Famed climate scientist Steven Schneider dies
Steven Schneider, one of the most influential and talented climate scientists of our time, died on Monday. Ricky Rood has a tribute to Dr. Schneider in today's blog. Ricky comments, "He is known for feistiness. His last book was Science as a Contact Sport: Inside the Battle to Save Earth's Climate. He was a man who was, bluntly, harassed and threatened by those who did not like his message. He never shrank from the battle."

Jeff Masters

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Quoting flsky:

Any way to slow this graphic down a bit?


I dont know about slowing it... but you could just move your mouse over the hours at the top of the screen and look at it frame by frame..
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convection is better organized now - TD tomorrow?
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1460. jeebsa
Quoting StormW:
Greetings again!
Greetings any changes?
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Quoting StormW:
Greetings again!


Good afternoon.
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1249. WeatherNerdPR
This comment has been removed for violating the Community Standards.

My comment got removed :(
But 97L seems to be organizing. So bad news Baha.
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Quoting StormW:
Greetings again!
hi storm welcome back looks like 97L starting to pick up steam
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Seems to me 97L is looking better and may be moving more west which indicates S Fl. Tomorrow will be interesting to watch.
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MLC exposed.. but the system itself is starting to gain organized convection.

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i do not think you can check for observation on the north coast of haiti to see if we have west winds can you check in northeast cuba
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1452. IKE
Quoting CybrTeddy:


Pressures rise during the day and fall during the night. Pressures are falling when they usually rise.


Pressure usually rises in the morning...drops in the afternoon...rises in the evening...drops in the early morning.
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Quoting Tazmanian:



eeeeeeek


I posted the 00z instead of the 12z. My bad.
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1449. IKE
Quoting wfyweather:


such a small drop means nothing. pressure naturally fluctuates.


It typically drops in the early afternoon. Plus, are the readings from a PWS or an official source?
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Quoting xcool:
YEP ULL MOVE FAST


D'you burn your fingers or something? You type like you have a handfull of marbles
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1447. flsky
Quoting earthlydragonfly:
Afternoon my friends.

looks like some kind of rebuilding effort going on with 97 eh? Still getting some model support

Any way to slow this graphic down a bit?
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Quoting wfyweather:


such a small drop means nothing. pressure naturally fluctuates.


Pressures rise during the day and fall during the night. Pressures are falling when they usually rise.
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Quoting sailingallover:
http://weather.noaa.gov/weather/current/MBPV.html
Pressure down to 1011 and 30MPH sustained winds...
97L is developing


Just my opinion :). There are also vigorous tropical waves with that low of a pressure and 30-35 mph wind speeds without a closed circulation. I know there are NE winds as the system approaches and SE winds as the system departs. However, are there any West winds over northern Haiti? If there were, then a closed circulation would be in progress, and I would reconsider that this might be developing into a tropical cyclone (albiet, sheared). I don't know if this is the case yet, so I am still on board still saying its not going to develop due to wind shear :)
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Hello Gambler....
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1443. xcool
97L.LOOK LIKE TD IMO
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting CybrTeddy:
Looking ahead now on the ECMWF.. it has continued to show a strong tropical wave off Africa and a system in the Gulf. It kills off the system off Africa and look what's inland over Louisiana at 192 hours.




eeeeeeek
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1441. unf97
Quoting CybrTeddy:
What I think is going to happen the next few hours is that the ULL will actually start moving at a quicker pace than 97L rather than moving in tandem. Per that image by nrt, the area where 97L is has not moved as much as the ULL has westward.. in short the ULL is moving out quicker. Shear tendencies are dropping around and in front of the system.





Its going to be a battle of the ULL vs 97L.


CybrTeddy, that's been an all too familiar battle in the tropics since last season uh? LOL..
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nvm
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1439. scott39
I think S FL. will be ok as far as a bad TC because of the ULL. Im not convinced about the GOM though. TOO FAR OUT!
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1438. xcool
YEAH.WIND 27.0mph
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting NYX:


I remember that system all too well. The only saving grace for us here in SFL may be that it is only the end of July rather than the end of August. My main concern at this point is how warm the waters are between the system and the coast and if that may contribute any to rapid development. I doubt it but we sometimes manage to get sucker-punched down here ala Katrina and even Charley which spun up rapidly and turned unexpectedly hours before landfall.


Your greatest saving grace (at least at the moment) is the ULL shearing and choking this one...
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may be the ull will move in the gulf and stall
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Quoting 7544:
from 1013 two mb drop this time now 1011 looks like its getting stronger


such a small drop means nothing. pressure naturally fluctuates.
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The position of the ULL relative to the movement of 97L is key to it's potential for development....As some of you are mentioning, the Gulfstream will be a good tool for sampling what is happening in the upper levels around the ULL and 97L....As long as the dry-sinking air in the ULL is in close proximity 97L, it will not have much room to breathe and develop. They are both inextricably intertwined at the momement.
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pine cay has had winds above 30mph on and off for over 5 hours now..impressive!
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29.79 inches now at Pine Cay

that is about 1008.7mbs
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Conditions over 97L has improved, wind shear from 30 knots down to 10-20 knots. Expect 97L to continue to ortganize well tonight.



97L


Has the look of a sheared TD, which will most likely be in 24-36 hours, maybe less if the ULL moves even faster.
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1430. 7544
looking better xcool now pres dropping
Member Since: May 6, 2007 Posts: 0 Comments: 6617
afternoon earthly
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Quoting NCHurricane2009:
The key is the upper low needs to move FASTER to the west than 97L. Rather, it seems 97L and the upper low are moving westward in tandem, this would keep shearing 97L for a while. The graphics Floodman posted seem to show the upper low in the eastern Gulf of Mexico by 48 hours. I think that would place 97L in southern Florida by that time? That would place 97L in the SE quadrant of the upper low, thus continued SW wind shear.


If you look at the projected path, 97L (or whatever it will be called by then) should be in a pretty fair environment at 72 hours, but hell, tomorrow we may find that projected conditions are radically different from right now...

Hard to tell with low end systems like this and there's where the modeling tends to fall down...

Hmmm...is there an echo in here?
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Afternoon my friends.

looks like some kind of rebuilding effort going on with 97 eh? Still getting some model support
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1426. xcool
YEP ULL MOVE FAST
Member Since: September 26, 2009 Posts: 2 Comments: 15603
1425. 7544
from 1013 two mb drop this time now 1011 looks like its getting stronger
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1424. xcool
97L ;)
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1423. scott39
Quoting NCHurricane2009:
The key is the upper low needs to move FASTER to the west than 97L. Rather, it seems 97L and the upper low are moving westward in tandem, this would keep shearing 97L for a while. The graphics Floodman posted seem to show the upper low in the eastern Gulf of Mexico by 48 hours. I think that would place 97L in southern Florida by that time? That would place 97L in the SE quadrant of the upper low, thus continued SW wind shear.
Have you noticed that the ULL has gained a little lattitude in the last couple of frames?
Member Since: June 13, 2009 Posts: 0 Comments: 6706
1422. leo305
ULL may be moving a bit faster than 97L
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What I think is going to happen the next few hours is that the ULL will actually start moving at a quicker pace than 97L rather than moving in tandem. Per that image by nrt, the area where 97L is has not moved as much as the ULL has westward.. in short the ULL is moving out quicker. Shear tendencies are dropping around and in the Bahamas while imparting some substantial shear over the system current.



Looking at current satellite the system has become better organized while taking on a sheared look. Pressures are now down to the 1012 - 1011, and winds are starting to shift. The GIV is in the air, so we'll get some good data out of that for the models. If I had to say, things are looking a little better for 97L than this morning. Its going to be a battle of the ULL vs 97L.
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1420. NYX
Quoting Floodman:


Well, to be honest there are some similarities between 97L and the other, more famous system...the ridge building into the SE for one...


I remember that system all too well. The only saving grace for us here in SFL may be that it is only the end of July rather than the end of August. My main concern at this point is how warm the waters are between the system and the coast and if that may contribute any to rapid development. I doubt it but we sometimes manage to get sucker-punched down here ala Katrina and even Charley which spun up rapidly and turned unexpectedly hours before landfall.
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Quoting msgambler:
Tim, stirring the pot early this afternoon?


Ya ya i know.....hehehehe.....be very very quite ...i'm hunting wabbit.....LOL

We really need 97L to intensify some so it goes North some......if it goes thru the Strait and misses Florida......She will be a much more dangerous Storm down the road with a lot of GOM for her viewing and digesting.....we need 97L to gain some lattitude and not pass south of Florida as that could be very ugly for Texas / Louisiana!!!
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Quoting JamesSA:
That's an UH OH! track.


ROFLMAO, which one...if I lived down there.. they would all be Oh oh tracks.

Living up north.. this is sort of like watching nascar.. you know there is going to be a wreck... your just not sure when and how bad.
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1417. leo305
Quoting sailingallover:
http://weather.noaa.gov/weather/current/MBPV.html
Pressure down to 1011 and 30MPH sustained winds...
97L is developing


that means the center is directly south of the turks and caicos
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poor BP



looks like will see what oil will do too a hurricane
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1415. russh46
Link



Plowing along
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1413. MTWX
Quoting StSimonsIslandGAGuy:
Yeah patrap I don't think I'll be 'tangling with idiocy' much more. Time to block out all the below average posters and keep it there.

Anyway, my thoughts on 97L for what they are worth.

It looks better than it did last night.

More likely than not, it will be a tropical storm affecting south Florida.

Shear in the eastern Gulf when it moves there is not yet certain. However, 97L/Bonnie will probably move close to or over the Loop Current and could be a serious threat, if shear is favorable.

Back to the pool. In my old fashioned cammy shorts :)

Thats not fair some of us generally lurk unless we have a serious question or comment to post!
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1412. JamesSA
Quoting Orcasystems:
If anyone cares... models are slowly shifting south to Texas... hmmm and we are getting CAT #'s again.



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
That's an UH OH! track.
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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.