97L a threat to become a tropical depression on Wednesday

By: Dr. Jeff Masters , 1:31 PM GMT on July 20, 2010

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A tropical wave (Invest 97L) near the east coast of Puerto Rico has become more organized overnight and is a threat to develop into a tropical depression as early as Wednesday. The disturbance has brought heavy rains of 8+ inches to Culebra and Vieques islands over the past day (Figure 1), 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 - 20 knots, which may allow 97L to continue to develop today. Satellite images of 97L show a moderate area of disorganized thunderstorms, but no signs of a surface circulation, no low-level spiral banding, and no upper-level outflow. There is a large amount of dry air to the northwest of Puerto Rico that will interfere with development of 97L. Surface observations show only light winds over Puerto Rico, with no signs of a surface circulation. The Hurricane Hunters are on call to investigate 97L this afternoon, if necessary.


Figure 1. Total radar-estimated rainfall from Invest 97L.

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 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. We do have several models developing 97L into a tropical depression or tropical storm. The GFS and HWRF both take 97L to tropical storm status over the Bahamas by Thursday, with the storm then tracking over South Florida on Friday and entering the Gulf of Mexico on Saturday. The NOGAPS is similar, but portrays a weaker system. All of these models foresee a threat to the oil spill region by Saturday night or Sunday, with the storm making a second landfall somewhere between the Florida Panhandle and Louisiana. One factor potentially aiding the storm 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 remain moderate, 10 - 20 knots, over the next 4 - 5 days, and I believe the primary detriment to development of 97L 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. NHC is giving 97L a 40% chance of developing into a tropical depression by Thursday, which is a reasonable forecast. I think there is a 60% 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, and I put the odds of 97L making it to hurricane strength before reaching Florida at 10%. There is a better chance that 97L could attain hurricane strength in the Gulf of Mexico, perhaps 20%. These probabilities will depend heavily upon how long 97L (or Bonnie) spends over land or interacting with land over the next four days, which is very uncertain.

Time to cut the forecast numbers for the coming hurricane season?
Here are the number of Atlantic named storms, hurricanes, and intense hurricanes predicted by the various forecast groups in their late May or early June forecasts:

23 named storms: PSU statistical model
20 named storms: UKMET GloSea dynamical model
18.5 named storms, 11 hurricanes, 5 major hurricanes: NOAA hybrid statistical/dynamical model technique
18 named storms, 10 hurricanes, 5 intense hurricanes: CSU statistical model (Phil Klotzbach/Bill Gray)
17.7 named storms, 9.5 hurricanes, 4.4 intense hurricanes: Tropical Storm Risk (TSR), hybrid statistical/dynamical model technique (Note: TSR increased their numbers to 19.1, 10.4, and 4.8 with their July 6 forecast)
17 named storms, 10 hurricanes: FSU dynamical model
10 named storms, 6 hurricanes, 2 intense hurricanes: climatology

The group forecasting the lowest activity was the Florida State University group led by Dr. Tim LaRow. They use a new dynamical forecast model called COAPS, which is funded by a 5-year, $6.2 million grant from NOAA. This year's June forecast by the COAPS model called for 17 named storms and 10 hurricanes. However, Dr. LaRow emailed me yesterday to say that the COAPS model is now calling for reduced activity. Using the state of the atmosphere and ocean as of July 15, a new run of the COAPS model was performed over the weekend. The new forecast is now calling for two fewer hurricanes--a total of 15 named storms and 8 hurricanes (including Alex.) The COAPS model generated an "ensemble" of five different forecasts, done by varying the initial sea surface temperatures by a few percent at the beginning of the model run. These five forecasts came up with a range of 12 - 16 named storms (including Alex), and 7 - 10 hurricanes. It will be interesting to see when CSU issues its August 4 forecast if they also cut their numbers. With only one named storm (Alex) thus far this year, it's getting pretty hard to have a season with 19 or 20 named storms. Only four hurricane seasons since 1851 have had as many as nineteen named storms. These four seasons--1887, 1933, 1995, and 2005--all had at least three named storms by July 20.

"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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I believe we will have 2 more named storms in July. 97L will become Bonny and one of the waves in the eastern Atlantic or coming off Africa will be our C storm (don't remember the name). Then get ready for a crazy August/September. Any thoughts?
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97L and possible tracking is reminding me of a girl I used to Know...
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Quoting WeatherNerdPR:

Exactly. Since development seems more likely than non-development/dissipation, I'd say 60%. If not, serve me Low Fat Crow.

when did crows come in low fat?
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Quoting DestinJeff:


Man your Battle Curtains!


LOL!!! Love it!

Glad I'm not in the thick of things anymore...good thoughts going out to all of you and hoping that it just goes away...
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Quoting brla61:
Hey Aussie. Hope you're feeling better.

No i am not feeling better but not letting it get me down/depressed.
Thanks for you concern <3
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Quoting whs2012:
TV Meteorologist are so stupid to me...my meteorologist last night said that 97L probably wasn't going to develop into anything, and will probably just die out. He said the same about Ike. And he supposedly has a doctorate in meteorology? Funny!


so many people say this and in alot of cases i agree.

sometimes they are not even "REAL" Meterologists-
many on this blog are waaay better.

[StormW,Weatherguy03,456,Drak,Levi,Miami]
and many others.
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting MiamiHurricanes09:


Is that shear coming from the south west?
Because the SW quadrant of the storm seems to be quiet without much convection?
Member Since: July 20, 2010 Posts: 0 Comments: 225
Quoting whs2012:
TV Meteorologist are so stupid to me...my meteorologist last night said that 97L probably wasn't going to develop into anything, and will probably just die out. He said the same about Ike. And he supposedly has a doctorate in meteorology? Funny!

is he also on TWC perhaps?
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Member Since: July 15, 2006 Posts: 165 Comments: 52262
Watching 97 closely... Late morning hrs show what appears to be some banding developing north of were the greatest vorticity is.
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Quoting AussieStorm:

C,D


We will have lots of discussion between orange-ites and red-ites on this blog! lol.
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have there been any west wind to report yet??
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Hey Aussie. Hope you're feeling better.
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Quoting CyclonicVoyage:


Maybe, but the straight line of the OFCI is overdone as well. They never go straight.

Landfall between Miami-Broward line and Palm Beach-Martin line, IMO.
We'll see soon enough...
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting StormW:


Maybe just a little at the moment. Looks like the Caribbean disturbance is getting far enough west to not be a factor. WV loop imagery tends to indicate that. That's why we are seeing a slight improvement in 97L.

WV LOOP
Thanks
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Wind profiles and visual representation of 97L are definitely looking more like a tropical system.
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Member Since: July 15, 2006 Posts: 165 Comments: 52262
Quoting whs2012:


Are these different models, or was there just a shift to the west?


NHC_A98E, NHC_BAMD ,NHC_BAMM, UKMET models
Member Since: July 20, 2010 Posts: 0 Comments: 225
Quoting DestinJeff:
Bloggers, we should be ashamed!

97L has been performing very well for us after a long lull, and yet none of us have thought to give the recognition it deserves ...

So, 97L, let me be the first to do what should have been done 100s of posts ago ...

Ladies and gentlemen -- and Ike, I give you the NHC IR RAINBOW IMAGE OF 97L:


to bad its not an e storm ,, EVITA , would have been happy,, thanks all 4 the reports , weather here in pinehurst nc is HOT AND HUMID,,off topic , cant believe the us open is here in 2014 back to back mens and womens,, too dang hot to play,,take care and be safe all
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Quoting MiamiHurricanes09:
Development in the next 48 hours into a tropical depression seems likely. I reckon that they raise it to 50% or 60%. So, I'm tore between B. and C.

Exactly. Since development seems more likely than non-development/dissipation, I'd say 60%. If not, serve me Low Fat Crow.
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Quoting patrikdude2:
What Color circle do you guys think NHC will give
97L @ 2:00PM?

A.)Yellow
B.)Orange
C.)Red
D.)It will be a T.D.

C,D
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Quoting BobinTampa:
Ike, I know you're famous for saying 'we need some rain' and then getting 15 inches in the next week.

However, is there any truth to the rumor that on April 20th, you were doing some routine maintenance on your car and said 'dang, I need some oil.'????


ROFLMAO... I think I hurt myself
Member Since: October 1, 2007 Posts: 81 Comments: 26493
Quoting JRRP:

98L ?


there is no 98L, it is getting kind of tiresome when people declare invests, TDs and Tropical Storms when they don't actually exist
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414. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5081
Hi all,

I come back from a good workout and a little work (laughs), and I have seen that the pitch is picking up in here. I guess we are all a little storm deprived. Us here in Florida are always watching something in our neighborhood for our own curiosity though, whether it be a windy rainstorm or a Hurricane....

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Quoting Dropsonde:
97L will probably be given an upgrade to red at 2:00. Very nice mid-level rotation as evident in the 850 and 700mb vorticity, decent upper level divergence, quite strong lower level convergence (just a bit off center from the high vorticity), and its structure on satellite is very evidently cyclonic now and curling around the vort max. It needs to fill in some convection over that spot and spin down to the surface, but once it does that, I have to side with the people who say it'll take off. Shear will have dropped by then. And no offense to all the SFL people, but the potential of a second landfall is more worrisome to me right now. Most likely there will be shifts in the track, and I don't think it'll become clear just what part of the Gulf Coast will get it until a few days from now. Going to be a tense next several days if this develops the way it looks like it will.



Nicely stated. Thanks.

And, I know the NHC will go by the book on the call, but it wouldn't be a bad idea if development progresses a bit to get some strong, regular reports made through all the resources to help create significant awareness. In these warm waters, given half a chance these systems can certainly intensify quickly.
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Quoting MiamiHurricanes09:
That sharp shift to thew NW in the beginning of the TVCN/TVCC plot looks overdone.


Maybe, but the straight line of the OFCI is overdone as well. They never go straight.

Landfall between Miami-Broward line and Palm Beach-Martin line, IMO.
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Quoting CybrTeddy:


If it does.. 96 hours from now. Saturday.


that would depend on the actual track!
If it goes further North it may be longer than 96 hours.

the GFS this morning shows a large shift North in
the track Taking 97L actually into NFLA/SGA.

I personally think the models dont have a clue until
97L actually develops. If it develops.

Here is what the GFS 0Z is showing...
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting NOSinger:
Storm...got a question...Our local mets in New Orleans are saying that a strong "HIGH" will be in place (around the La/Miss line)by Fri. Bringing very dry air and HOT temps...Wouldn't that "HIGH" force anything that might be headed for the gulfcoast west??


Well, it didn't help back then...

Link
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Quoting StormW:


Purple. (j/k)


Color-caster!
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Thanks Orca! *sarcastic tone* One to watch, wait and see.
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Ike, I know you're famous for saying 'we need some rain' and then getting 15 inches in the next week.

However, is there any truth to the rumor that on April 20th, you were doing some routine maintenance on your car and said 'dang, I need some oil.'????
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Updated, and I am off to work :(



AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26493
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Well i feel like texas wont get this one
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NMFC Norfolk Tropical Feed
No Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
By Maritime.CDO@navy.mil (NMFC CDO) from Naval Maritime Forecast Center Norfolk Virginia. Published on .

As of Tue 20 Jul 2010 15:30:02Z



2010 Storms
All Active Year


Atlantic
97L.INVEST
East Pacific
NONE
Central Pacific
NONE
West Pacific
97W.INVEST(T.C.F.A.Cancelled)
04W.CHANTHU
Indian Ocean
NONE
Southern Hemisphere
NONE
Member Since: July 15, 2006 Posts: 165 Comments: 52262
Quoting StormW:


Purple. (j/k)
Is 97L competing for energy with the wave in the SW Carribean?
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Quoting patrikdude2:


Latest computer models


More and more models are taking this system through S.Florida... Interesting

BTW: I live in Broward County ,S Fla
Member Since: July 20, 2010 Posts: 0 Comments: 225
397. unf97
Quoting CybrTeddy:
Prediction for 2 PM TWO: 40% or 50%.


50% or 60% is where I would guess for the moment.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
is it just me, or does it look like the COC is trying to form on the east side of Puerto Rico??? that would shift the models again if it did form there...
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Thanks Dr. Masters! Good Morning everyone.
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97L will probably be given an upgrade to red at 2:00. Very nice mid-level rotation as evident in the 850 and 700mb vorticity, decent upper level divergence, quite strong lower level convergence (just a bit off center from the high vorticity), and its structure on satellite is very evidently cyclonic now and curling around the vort max. It needs to fill in some convection over that spot and spin down to the surface, but once it does that, I have to side with the people who say it'll take off. Shear will have dropped by then. And no offense to all the SFL people, but the potential of a second landfall is more worrisome to me right now. Most likely there will be shifts in the track, and I don't think it'll become clear just what part of the Gulf Coast will get it until a few days from now. Going to be a tense next several days if this develops the way it looks like it will.
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Hi guys and gals
I've been lurking this season.

Local new meteorologist is only saying we (S.W. Florida) might get some rain from the currect wave down by P.R. (no mention of anything possibly forming). I was very suprised to see the model forecast showing a possibly strengthing system.
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Quoting FLdewey:
Do I need a number two pencil to vote? Is this a scantron test?


Yes.. test ends now. You failed. Come back next year.
Member Since: July 8, 2005 Posts: 259 Comments: 23012
Quoting patrikdude2:
What Color circle do you guys think NHC will give
97L @ 2:00PM?

A.)Yellow
B.)Orange
C.)Red
D.)It will be a T.D.
Development in the next 48 hours into a tropical depression seems likely. I reckon that they raise it to 50% or 60%. So, I'm tore between B. and C.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting JRRP:

98L ?


Well, it ought to be.....
Member Since: September 1, 2007 Posts: 0 Comments: 1793

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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.