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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Quoting JRRP:

98L ?


Well, it ought to be.....
Member Since: September 1, 2007 Posts: 0 Comments: 1793
When is the high suppose to weaken?


Latest computer models
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OK, models and landfall

SHIP, DSHP,OFCI have a CAT 1 at Zoo's place

HWFI has it as a CAT 2 at Ikes.


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Prediction for 2 PM TWO: 40% or 50%.
Member Since: July 8, 2005 Posts: 259 Comments: 23013
Quoting Jeff9641:
Red!!!!!!!!


I agree on the red. Especially with a low forecast to develop now.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
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.


Blue
Member Since: September 1, 2007 Posts: 0 Comments: 1793
Quoting StormW:


Purple.


Two years ago they accidentally put a invest that was orange on the TWO to purple.
Member Since: July 8, 2005 Posts: 259 Comments: 23013
there is no 98L
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.


B
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376. JRRP
Quoting StormSurgeon:
98L is trying to get it's act together there east of the Yucatan........

Link

98L ?
Member Since: August 16, 2007 Posts: 0 Comments: 5084
B or D
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.
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Quoting CybrTeddy:
Perfect! That circle looks perfectly placed.
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98L is trying to get it's act together there east of the Yucatan........

Link
Member Since: September 1, 2007 Posts: 0 Comments: 1793
TVCC puts it landfaling in West Palm Beach. Great, was going to make plans with a girl, but no, this is gonna happen lol
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Member Since: July 8, 2005 Posts: 259 Comments: 23013
I think it will make landfall between nola and penscola
365. myway
Quoting MiamiHurricanes09:
Yup, category 1 hitting SFLA in 96 hours.


Subject to change. Tracks were thru Cuba yeterday afternoon.
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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:




LOL!
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Quoting CyclonicVoyage:



TCVN/TVCC would put landfall right around the Jupiter area.

Just moved there, lol.
That sharp shift to thew NW in the beginning of the TVCN/TVCC plot looks overdone.
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362. unf97
Quoting MiamiHurricanes09:
Miami NWS paying attention to 97L...


As they should of course.
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Quoting extreme236:


I don't see this taking until Thursday night in my opinion. Probably tomorrow's recon if the organization continues.

I'm thinking, Wednesday night Thursday morning, my time, or Wednesday morning Wednesday night your time.
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Quoting Hardcoreweather2010:



TCVN/TVCC would put landfall right around the Jupiter area.

Just moved there, lol.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
What everybody fail to realize is that this thing has alot of time to organize it has about 5 days before it hits fla so dont be fooled because it not lookin good now 5 days can make a big difference
358. JRRP

Member Since: August 16, 2007 Posts: 0 Comments: 5084
Miami NWS paying attention to 97L...
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355. Relix
Strong circulation is evident east of Fajardo and Ceiba in PR though. Competing one perhaps?
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Take a look at the radar , a warning box has appeared just east of puerto rico

Maybe a Center Of Circulation trying to develop there?good convection
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301. Chicklit 10:14 AM CDT on July 20, 2010
Good news for Baha as it isn't forecast to get to named status until it gets into the Gulf.
By the way, been burned one to many times by impressive waves coming off Cape Verde this year. From now on am waiting until they get to 50W before I so much as look at them.



LOL, Chicklet - naaaahhh, you keep watchin'! The CV's can be a bit deceptive sometimes when they hit the Atlantic, but these CV's, as you know, can be quite the deadly storms, having so much time to get their acts together, intensify, push large volumes of ocean and all that. We've hit that time of the season and it only takes one - one beast, doesn't even really have to be a beast. Development conditions will improve with shear staying relaxed, the ITCZ moving more northwards, dust settling, and all the warm waters throughout the MDR. It's not likely to be a lackluster season. I loathe the CV season.
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nice looking wave about to pass off of Africa.
the tropics are definately gearing up.

Good To see ya on the blog again weatherguy03!

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


Friday
96 hours is the best bet.
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Quoting Gatorstorm:
what is the timeframe should it impact Florida?


Friday
Member Since: January 30, 2010 Posts: 0 Comments: 3259
000
FXUS62 KMFL 201442
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
1042 AM EDT TUE JUL 20 2010


...DANGEROUS, LIFE-THREATENING RIP CURRENTS ATLANTIC BEACHES...
...WATCHING VIGOROUS TROPICAL WAVE NEAR PUERTO RICO FOR POSSIBLE HEAVY
RAIN/GUSTY WINDS FRI-SAT...

.UPDATE...FORECAST IS ON TRACK AND SO NO CHANGES LOOK NECESSARY.
STRONG EASTERLY WIND FLOW CONTINUES...RESULTING IN DANGEROUS RIP
CURRENTS AT THE ATLANTIC BEACHES. THIS WILL ALSO NOT ALLOW A GULF
BREEZE TO DEVELOP...ALLOWING TEMPS TO AGAIN SOAR FOR THE NAPLES
AREA...POSSIBLY TOWARDS THE RECORD OF 95 TODAY. NAPLES HAS HIT 95
FOR 3 STRAIGHT DAYS NOW! HOT PATTERN CONTINUES FOR THE GULF COAST.
DRY WEATHER WILL PREVAIL...WITH JUST THE POSSIBILITY FOR A FEW
SHOWERS OR STORMS.

NHC IS MONITORING THE VIGOROUS TROPICAL WAVE NEAR PUERTO RICO FOR
POSSIBLE TROPICAL CYCLONE DEVELOPMENT. REGARDLESS OF
DEVELOPMENT...THERE IS THE POTENTIAL FOR HEAVY RAIN/GUSTY WINDS
ACROSS SOUTH FL IN THE FRI-SAT TIME FRAME...WITH FOCUS
LOOKING LIKE FRIDAY. HAVE INCLUDED THIS IN THE HAZARDOUS WEATHER
OUTLOOK. FORECAST DETAILS WILL BE MORE PINNED DOWN IN THE COMING
DAYS...AND OF COURSE IS ALL DEPENDENT ON WHETHER OR NOT THIS WAVE
DEVELOPS. SINCE YESTERDAY...THE TREND IS TOWARDS DEVELOPMENT AND
SO THIS WILL BE WATCHED CLOSELY.


/GREGORIA
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Quoting Gatorstorm:
what is the timeframe should it impact Florida?


About Saturday-Sunday Night.
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Why the big shift in models?
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Quoting Gatorstorm:
what is the timeframe should it impact Florida?


If it does.. 96 hours from now. Saturday.
Member Since: July 8, 2005 Posts: 259 Comments: 23013
Crow for JM? We'll see. He gives it 60% of getting named Bonnie but 20% of making it to hurricane status, and 10% chance of hurricane strength before reaching Florida.
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what is the timeframe should it impact Florida?
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Quoting extreme236:


Not always. I recall him forecasting a 20% chance of Alex becoming a hurricane in the Gulf, and well we see what happened. SHIPS does infact forecast 97L to become a hurricane.
SHIPS did very well with the intensity of Alex once it was in the GOMEX.
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Quoting rlk:
Recall that 2004 was an extremely active and destructive season -- "only" 15 named storms, but 6 majors including 3 cat 4's and a cat 5 (Ivan).

2004 was crazy because during the two months of activity during that season, they wouldn't stop coming. Except for the three day gap between Danielle and Francis, there was at least one storm active from Alex to Lisa, from July 31st to October 3rd!

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Quoting extreme236:


I don't see this taking until Thursday night in my opinion. Probably tomorrow's recon if the organization continues.


I could very well be wrong. I just hope it doesn't become the 'Joker' part 2.
Member Since: July 8, 2005 Posts: 259 Comments: 23013

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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.