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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On the "going to Cuba" topic: models on the weekend called for the more southerly track because they were forecasting a weaker system. Looks like they're doing the same again today, hence, imo the retrograde to the left of track.
Member Since: October 25, 2005 Posts: 19 Comments: 20695
Storm/Levi/Reed/

Can a ULL sometimes help outflow? If so, when?

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Quoting srada:
So.the same models that predict the path of storms also predict the steering layers? Wouldnt you have to discount that to some degree as well if the models are not intializing the storm right, how much of an accuracy would the steering maps be? Im learning so be gentle..


It's more like what will the coordinates be if you start from x, given an array of different varibles (a ULL at this strength in this location, a ridge building in at this strength at this time interval).

The different end results should be derived from the difference in the variables, and not the intialization point in space
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1759. Patrap
Ive put up nuff Imagery in 5 years to retire on easily.

Dollar a Post..would be Like 2.8 Million by now easily.
Member Since: July 3, 2005 Posts: 414 Comments: 125572
Quoting Orcasystems:
The G is still flying around to the North



AOI

TS BUSTED FORECAST ALIBI


Yep it will clockwise around 97L and head back to base.
Member Since: Posts: Comments:
Folks pretty quick to jump on you around here lately when all some of us are trying to do is learn about the tropics......Its starting to get old really fast.....Thanks to all of regulars who try to actually try to help and educate and no thanks to those who just want to argue, for arguments sake, and put people down just because they aren't as skilled as you would like them to be......I'll see all of you next year (maybe)....Good Night.
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1755. IKE
Providenciales, TI (Airport)...at 21.8N and 72.3W
Updated: 26 min 3 sec ago
Heavy Rain Showers
79 °F
Heavy Showers Rain
Humidity: 94%
Dew Point: 77 °F
Wind: 24 mph from the East
Pressure: 29.89 in (Rising)
Visibility: 5.0 miles
UV: 3 out of 16
Clouds:
Scattered Clouds 1500 ft
Mostly Cloudy 2500 ft
(Above Ground Level)
Elevation: 13 ft
Member Since: Posts: Comments:
looks like shes trying to fire new convection on the north side again...
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1752. IKE
Quoting will45:


she is safe Ike she is up here in NC lol


Thankfully:)
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1751. tramp96
Quoting StSimonsIslandGAGuy:
Repost

I got an email today that was kind of sad. About innocuous comments that person made being flagged and removed in Dr. Master's blog.

I suspect, but don't know for certain, that ALL comments that are flagged are automatically removed now. That admin has lost some patience and is getting stricter.

At any rate, the overall tone there has reached a new low. Disagreements and fighting about the most stupid stuff.


So I performed an experiment. I asked a question about long term shear forecasts for the eastern Gulf. For when 97L/Bonnie is there. I looked back through hundreds of comments, and posts by knowledgeable bloggers are almost submerged in dreck.

Yes I know where the shear forecast maps are, btw. But I thought it was a reasonable question.

One blogger, Levi32, answered my question straight away.

But two other bloggers really jumped on my case, basically for asking a stupid question. I guess I am expected to know better, and have higher standards, but really! I mean coming down on anyone for asking a decent question is wrong.

And, well---actually there are probably a lot of occasional posters who don't know where to find out about long range shear forecasts. So eliciting that information may have been helpful.

One comment by those who criticized me was yanked (not flagged by me), although it was not nice.

But it just seems like people are prepared to fight in Dr. Master's blog--that people are being flagged for no reason. And attacked.

That's just sad.

So for the person who was concerned about having "comments removed for violating community standards"---don't worry about it. I've even seen some posts by StormW flagged recently, and I seriously doubt he was doing anything wrong.

I expect the comments in Dr. Master's blog will be a total nightmare when the next major is bearing down on the USA. That will be sad too.

The lull has been nice. I was learning more and Levi and Storm had time to answer a lot of ?s
Member Since: Posts: Comments:
Couple of things while the blog seems quieter:

1) can we have more image posting again? The problem with having to go to a separate window all the time is that it makes it harder to keep up with the flow of the blog. I agree it can be taken to an extreme, but there are uses also. e.g. a picture paints 1000 wds sometimes. Pple who need help with interpreting models can do what we did - read up on them. Pat is often posting info about the different models, and NWS has info readily available.

2) Glad to see some more focused discussion this afternoon. I'm really interested to see what we'll be getting from dropsonde / Google Earth mapping as the evening progresses.
Member Since: October 25, 2005 Posts: 19 Comments: 20695
1749. Patrap


Quoting Floodman:


Pat, my point is that you can't rely on the end result if the initial data is incorrect...do you now understand what I'm saying? The models aren't worth anything if they don't start where the CC is...the differences come from different variables effecting track from the CC location...that would be kinda like saying "How far is it from KC to NOLA if I start from St Louis?"


I Never mentioned rely.

Its Guidance..as they wouldnt publish GIGO.





Member Since: July 3, 2005 Posts: 414 Comments: 125572
1748. will45
Quoting IKE:



Hmmm.


she is safe Ike she is up here in NC lol
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1747. hydrus
Quoting ElConando:


It is Karen's remnants I tell ya!
If it is Karen, does it keep the name Karen or will it be Bonnie?..:)
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1746. IKE
Quoting Patrap:
Correct is a figurative term.

Any Model run on a Given system can be "correct" in retrospect.

But for Guidance,,they just that..

...Guidance

12z Latest GFS Ensemble Member Tracks
Invest97
GFS Ensemble Members



Jeez...that sure looks like Cuba.
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be thankful if you get another 97l in this spot in aug or sept then big trouble.ty uul.
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1744. srada
Quoting IKE:



Hmmm.


Please dont put that on me..LOL..it was a typing error
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1742. srada
So.the same models that predict the path of storms also predict the steering layers? Wouldnt you have to discount that to some degree as well if the models are not intializing the storm right, how much of an accuracy would the steering maps be? Im learning so be gentle..
Member Since: Posts: Comments:
1741. xcool
ha
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting Patrap:


Different end solutions.

If all Models wound up in the same Line.

What would be the Purpose?

Each set has their own characteristics,,Like Humans



Pat, my point is that you can't rely on the end result if the initial data is incorrect...do you now understand what I'm saying? The models aren't worth anything if they don't start where the CC is...the differences come from different variables effecting track from the CC location...that would be kinda like saying "How do I get from KC to NOLA if I start from St Louis?"

**editted**
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Quoting Tazmanian:
Level Wind Direction Wind Speed
1019mb (Surface) 60° (from the ENE) 20 knots (23 mph)
850mb 95° (from the E) 22 knots (25 mph)
750mb 75° (from the ENE) 26 knots (30 mph)
660mb 100° (from the E) 33 knots (38 mph)
566mb 100° (from the E) 33 knots (38 mph)
520mb 155° (from the SSE) 26 knots (30 mph)
467mb 175° (from the S) 13 knots (15 mph)
434mb 170° (from the S) 11 knots (13 mph)
390mb 195° (from the SSW) 15 knots (17 mph)
339mb 185° (from the S) 18 knots (21 mph)
320mb 155° (from the SSE) 19 knots (22 mph)
309mb 165° (from the SSE) 18 knots (21 mph)
278mb 145° (from the SE) 22 knots (25 mph)
246mb 145° (from the SE) 21 knots (24 mph)
236mb 160° (from the SSE) 18 knots (21 mph)
217mb 205° (from the SSW) 28 knots (32 mph)
186mb 210° (from the SSW) 39 knots (45
mph)
170mb 190° (from the S) 16 knots (18 mph)
162mb 220° (from the SW) 22 knots (25 mph)


That's very high up in the atmosphere Taz, the surface winds were only 23 mph
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1737. Patrap
Correct is a figurative term.

Any Model run on a Given system can be "correct" in retrospect.

But for Guidance,,they just that..

...Guidance

12z Latest GFS Ensemble Member Tracks
Invest97
GFS Ensemble Members

Member Since: July 3, 2005 Posts: 414 Comments: 125572
Quoting BahaHurican:
It's going to be a matter of closed or not closed. If it isn't closed when they fly it, but it looks good, they might up the chances. Otherwise I think they'll stick w/ the 50% at 8:00.


Agreed, most likely staying at 50%, but wouldn't be surprised if they raise it up to 60% do to pressure falling and higher winds and an actual LLC.
Member Since: July 1, 2008 Posts: 13 Comments: 7334
1735. Patrap
Quoting Floodman:


So, with an inconclusive center location, you get numerous results, none of which can be correct as the initial data was incorrect? Gee, as an old programmer, that sounds for all the world like GIGO


I suggest a a tutorial Floodman.

The Guidance Flow dosent just affect a "center"..the flows aloft affect the whole envelope.


Its Guidance..never Gospel

Thats the NHC Line when we get a Named Sytem



Member Since: July 3, 2005 Posts: 414 Comments: 125572
1732. IKE
Quoting srada:
it looks like the 18z steering maps change somewhat from teh

is this what the GFDL is picking up on?



Hmmm.
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Quoting Patrap:


Different end solutions.



So, with an inconclusive center location, you get numerous results, none of which can be correct as the initial data was incorrect? Gee, as an old programmer, that sounds for all the world like GIGO
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I'm out. See you in about 30 Minutes.
Member Since: July 7, 2010 Posts: 0 Comments: 5521
1726. srada
Quoting Jeff9641:


Well put!! I was trying to explain to StormW that the ULL appears to wanna tug on 97L and pull it further north than some think. We seem to get a set up like this once or twice a year.


is this what the GFDL is picking up on?
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1725. WxLogic
Sure hope the GIV can help on the 00Z runs tonight.
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Level Wind Direction Wind Speed
1019mb (Surface) 60° (from the ENE) 20 knots (23 mph)
850mb 95° (from the E) 22 knots (25 mph)
750mb 75° (from the ENE) 26 knots (30 mph)
660mb 100° (from the E) 33 knots (38 mph)
566mb 100° (from the E) 33 knots (38 mph)
520mb 155° (from the SSE) 26 knots (30 mph)
467mb 175° (from the S) 13 knots (15 mph)
434mb 170° (from the S) 11 knots (13 mph)
390mb 195° (from the SSW) 15 knots (17 mph)
339mb 185° (from the S) 18 knots (21 mph)
320mb 155° (from the SSE) 19 knots (22 mph)
309mb 165° (from the SSE) 18 knots (21 mph)
278mb 145° (from the SE) 22 knots (25 mph)
246mb 145° (from the SE) 21 knots (24 mph)
236mb 160° (from the SSE) 18 knots (21 mph)
217mb 205° (from the SSW) 28 knots (32 mph)
186mb 210° (from the SSW) 39 knots (45
mph)
170mb 190° (from the S) 16 knots (18 mph)
162mb 220° (from the SW) 22 knots (25 mph)
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Quoting Floodman:


resulting in?


Not sure the question, they start a different initial location for each ensemble member.
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Quoting reedzone:


Agreed! Come on now, they classified 96L as TD2 when it had little to no convection. Why can't they do the same with this one? Bugs me when they do that.. 50-60% is a very good bet because despite how it looks convective wise, 97L has organized quite well this afternoon, developed a LLC (exposed). It's well on it's way to TD status for tomorrow.
It's going to be a matter of closed or not closed. If it isn't closed when they fly it, but it looks good, they might up the chances. Otherwise I think they'll stick w/ the 50% at 8:00.
Member Since: October 25, 2005 Posts: 19 Comments: 20695
The G is still flying around to the North



AOI

TS BUSTED FORECAST ALIBI
Member Since: Posts: Comments:
1718. Patrap
Quoting Floodman:


resulting in?


Different end solutions.

If all Models wound up in the same Line.

What would be the Purpose?

Each set has their own characteristics,,Like Humans

Member Since: July 3, 2005 Posts: 414 Comments: 125572
Quoting StormW:
18Z 700-850mb Layer Mean Steering

But what about the image below along with does the ULL shear it but also pull it north?

ARRGG strips off FNMOC images mean I have to wait for adds to download
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well hell 97L wont do nuffin

its going to Cuba or the ULL will eat it right?
Member Since: March 10, 2010 Posts: 1 Comments: 7233
1715. Patrap
Quoting ElConando:


It is Karen's remnants I tell ya!


Naw..its 95L still dragging dat front around Im a thinking.

Member Since: July 3, 2005 Posts: 414 Comments: 125572
Quoting StormW:


It's no problem. Just posted the link, as the same question has been asked about 5-6 times. Figure ya can get the full scoop in detail.


That's what I like about you Storm your always polite and never try to hurt anyone's feelings. Seriously!
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jeff9641:how can a surface feature this weak be steered by a ULL at 200mb?????doesn't make sense meteorlogically speaking....
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Quoting nrtiwlnvragn:


All models except the ECMWF have the capability of center relocation, but it is a manual process. If the model center does not do it, you get the spun-up center from the model as in the recent GFS ensemble members starting from different locations:

AL 97 2010072112 03 AP01 0 199N 711W
AL 97 2010072112 03 AP03 0 201N 718W
AL 97 2010072112 03 AP04 0 205N 708W
AL 97 2010072112 03 AP06 0 203N 714W
AL 97 2010072112 03 AP07 0 196N 711W
AL 97 2010072112 03 AP08 0 205N 719W
AL 97 2010072112 03 AP09 0 204N 720W
AL 97 2010072112 03 AP10 0 199N 719W
AL 97 2010072112 03 AP11 0 198N 719W
AL 97 2010072112 03 AP12 0 202N 708W
AL 97 2010072112 03 AP13 0 195N 700W
AL 97 2010072112 03 AP14 0 203N 717W
AL 97 2010072112 03 AP15 0 197N 720W
AL 97 2010072112 03 AP16 0 200N 721W
AL 97 2010072112 03 AP18 0 209N 719W
AL 97 2010072112 03 AP19 0 201N 711W


resulting in?
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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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