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 Orcasystems:
The Models have backed off on the CAT 1 landfalls... thats a good start.



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI


Can you provide me the network link to your model KML? Just right click it and then hit properties.
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Quoting cg2916:


The ridge is too strong for it to go that north, the models have shifted south, I don't know what the models were thinking earlier.

they reliable models are still thinking that the ridge will break down. Until they shift south I will not be on board. And liek I said they have shifted north. Last night from WPB to the keys this morning form Cape Canaveral to Miami
Member Since: August 26, 2008 Posts: 0 Comments: 2182
Quoting Skyepony:
slumming the buoys..just beginning to see a few west winds & pressures falling again. We need a well placed ship..


Yepper.....or maybe a recon flight to produce some hard data to initialize the model runs.GIGO
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Quoting Jeff9641:
Remember folks most the rain & wind will be N and E of the center. So a S FL landfall will likely mean most impacts will be across C and N FL.

With an organized tropical system, that is true, but with a disorganized tropical wave, it will vary with environmental factors. Even if it does become a TS prior to reaching FL, it is still likely that it won't be extremely organized, therefore I'd look for disproportionate distribution of rainfall as well as any substantive wind field it may have developed. As for those wondering how it could possibly wander northward of SFL, look no further than the hint of a weakness in the ridge near 29N, 75W. Not that it's likely, I'm just offering a possibility. I believe the only reason the HWRF and GFDL take it so far north is because they are runs from 06Z, and LMWA's at that time weren't showing a ridge that extended over the state of Florida- they were showing a ridge which extended to about 74W.
I'm still taking it through South Florida, into the EST GOM, and recurving it over the WST FL Panhandle and coastal AL-MS areas.
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Quoting Funkadelic:
After 97L I think we will continue to go back to the lull that we were previously in. I just think the tropical Atlantic is a hostile place in the upper atmosphere right now. We may go until the middle to late August with nothing much. Not being a down caster but this is just my opinion. No storms = GOOD.


How come the shear remains so high? Anyone?

Quoting txsweetpea:

Is recon still on for today?


Nope, postponed until tomorrow, it still is only starting to get back it's MLC, no signs of an LLC yet.
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Quoting leo305:
''latest model runs take it to the florida straights/SFL


thanks Leo for helping him out....he must be a northcaster
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The Models have backed off on the CAT 1 landfalls... thats a good start.



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting txsweetpea:

Is recon still on for today?
I believe Dr. Masters said it was postponed until tomorrow.
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202. Skyepony (Mod)
slumming the buoys..just beginning to see a few west winds & pressures falling again. We need a well placed ship..
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Quoting Hardcoreweather2010:
Good Morning here are the latest model runs from the NHC



If that holds true this could be very problematic I must say
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Quoting gator23:

see what i worte below, there has been a conssitent northward shift from yesterday and our most reliable models have caleld for a central florida strike.


The ridge is too strong for it to go that north, the models have shifted south, I don't know what the models were thinking earlier.
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Quoting cg2916:
I don't think they'll lower the chances. Since 8 AM, it's become better structurally organized, the area of convection is growing, and conditions are starting to improve as the ULL is starting to move W. I think they'll hold it at 60%.
yes good points
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Is recon still on for today?
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Quoting DestinJeff:
Does everybody understand that model solutions going over your house doesn't make you any more BA than anyone else?

the founding prnciple of Kent law
Member Since: August 26, 2008 Posts: 0 Comments: 2182
Convection is definitely starting to hold its own around 97Ls circulation!
Member Since: June 13, 2009 Posts: 0 Comments: 6890
Quoting DestinJeff:
Man 2010 is the year of sluggish development. I blame the 24/7 News Cycle.


LOL, this happens every year. Remember Fay, Dolly?
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Quoting leo305:
''latest model runs take it to the florida straights/SFL

no they dont, they take it anywhere from Cape Canaveral to Miami as per the Docs posting up there. Last night it was anywhere from the keys to Martin county. That IS a northward shift.
This is totally kents law right now
Member Since: August 26, 2008 Posts: 0 Comments: 2182
I don't think they'll lower the chances. Since 8 AM, it's become better structurally organized, the area of convection is growing, and conditions are starting to improve as the ULL is starting to move W. I think they'll hold it at 60%.
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Quoting Funkadelic:
What is the CURRENT speed of 97L anyone know? It seems really slow but could be my eyes.
West north west at 10mph according to the nhc
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Quoting Jeff9641:
Remember folks most the rain & wind will be N and E of the center. So a S FL landfall will likely mean most impacts will be across C and N FL.




true,but if its sheered TC it could be any side,but in general the onshore flow is where the heavier wx should be...
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Quoting gator23:

see what i worte below, there has been a conssitent northward shift from yesterday and our most reliable models have caleld for a central florida strike.
''latest model runs take it to the florida straights/SFL
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Quoting Skyepony:
tsunami buoy alert triggered east of Charlston, SC.. looks like may be a problematic buoy?


Sure hope so, because that's our whole tourist and seafood industry in SC.
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Quoting Caribbeanislands101:

Any world on the this disturbance from africa?
Development will be slow to occur if there is any development of the wave at all
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Quoting BradentonBrew:


It's not common knowledge. There are so many impressionable people here that are new. I respectfully ask that you post truths and not cherry-picked thoughts that you deem common knowledge.

see what i worte below, there has been a conssitent northward shift from yesterday and our most reliable models have caleld for a central florida strike.
Member Since: August 26, 2008 Posts: 0 Comments: 2182

Any word on the this disturbance from africa?
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Check the latest satellite images, everyone... Looks to me like this thing is starting to crank up. There is a definite spin now, and all of the heavy thunderstorms are collected right near the center.

Unlike yesterday, where I was saying "wait until it gets a center... it won't develop into anything until then," now I'm saying that we'll likely have a TD within the next 24-36 hours or so, unless something starts inhibiting it.
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Quoting CybrTeddy:
Seems NHC agrees with me, Tropical Depression not likely to form today. I almost guarantee it actually, if anything they might drop it to orange at 2 pm. That being said, as the ULL kicks westward away from 97L it should become better organized.. we might see a TD Friday morning in that case.
it wasnt supposed to get its act together until today and tomorrow anyways
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Good Morning here are the latest model runs from the NHC

Member Since: January 24, 2010 Posts: 0 Comments: 529
Seems NHC agrees with me, Tropical Depression not likely to form today. I almost guarantee it actually, if anything they might drop it to orange at 2 pm. That being said, as the ULL kicks westward away from 97L it should become better organized.. we might see a TD Friday morning in that case.
Member Since: July 8, 2005 Posts: 259 Comments: 24484
Quoting IKE:


I see that, but I see dry air encroaching further on the invest. I see a slight increase in convection near the center, but that ULL is holding firm on it....for now.


Dy air won't be a big issue with 97L. You can actually see a shield of moisture protecting the invest as the ULL moves westward. Development should re-occur tonight. Every invest has it's bad days :)
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174. Skyepony (Mod)
tsunami buoy alert triggered east of Charlston, SC.. looks like may be a problematic buoy?
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172. IKE
Quoting Jeff9641:


Ike look at the visible. A very impressive mid level spin and infact the NHC has nailed the placement.


I see that, but I see dry air encroaching further on the invest. I see a slight increase in convection near the center, but that ULL is holding firm on it....for now.
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From JAX NWS

FRIDAY...TROPICAL WAVE AXIS WILL SHIFT NORTHWEST INTO THE FORECAST
AREA
WITH RAIN CHANCES INCREASING INTO THE 40-50% RANGE ACRS NERN FL
WITH 20-30% CHANCES REMAINING OVER SERN GA. PRECIP WATER AMOUNTS
WILL ONCE AGAIN INCREASE TO AROUND 2 INCHES. EASTERLY ONSHORE FLOW
WILL LIKELY BECOME BREEZY ALONG THE COASTAL AREAS AND INCREASED RAIN
CHANCES ACRS NERN FL WILL HOLD MAX TEMPS TO AROUND 90 WHILE SERN GA
SHOULD STILL REACH INTO THE LOWER/MID 90S.
Member Since: August 26, 2008 Posts: 0 Comments: 2182
Some of you please use the ignore button and dont post ridiculous repetitive Quotes! When and if 97L takes off or any other system takes off, everybody will want to read troll crap even less at that time!
Member Since: June 13, 2009 Posts: 0 Comments: 6890
Quoting RJT185:



Not as good as many were expecting or some even hoped. But the signature is there, and from the most recent data/images seems to be trying to get its act back together again. StormW is working on his synopsis which I can't wait to read.

Okay, yeah, it doesn't look that great, the DR had some very high mountains, that may be the problem, maybe once it pulls away from the island.
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Quoting MiamiHurricanes09:
I'm only making a comparison between the 06 model plots and the 12z model plots, not last night's. And, I don't know where the GFDL and HWRF are as a ridge to the north would not allow 97L to go that far north. Plus, 12z models are hinting at south Dade yet again after the 06z plots were hinting at central Florida.


Im looking at consistency, I am seeing a more northward trend from yesterday, I am also seeing that our most reliable tropical models are in great agreenment calling for a central Florida strike, also these more reliable models have been more consistent then the other models have with 97L. You know better than anyone that ridges break down and that is what the models are antcipating. So I am going to pick my pony with them, if they shift South I will agree with you until then Palm Beach to Cape Canaveral look out.
Member Since: August 26, 2008 Posts: 0 Comments: 2182
Quoting stillwaiting:




jason,please just relax for a minute,its going to be a long busy season from here fowrard,97L has been effected by sheer,dry air and land interaction.Today should be a day of slow surface organization as the ULL weakens and moves towards the NW carib as 97L moves WNW towrds the lower bahamas area.Factors have not been forecast to be favorable until tomorrow and thats been the forecast!!!!......
Exactly we should start seeing a improved appearance later today
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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.