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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Puerto Rico and nearby islands have been taking a beating from this storm LOL , i think it finally is beginning to move north westward
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536. xcool
wunderground go off line oh boyyyy
Member Since: September 26, 2009 Posts: 2 Comments: 15648
Tranquility Base Here,The Eagle has Landed

But what isnt well known by millions alive then and today,

is that is was close.


Closer than a "wings wiggle to Flame".



Mike Collins,Neil Armstrong and Buzz Aldrin were and are today the First Humans to return from Lunar Orbit with something they didnt leave with from Earth.



That Box o rocks under their couches firmly strapped in when they Splash downed in the Command Module July 24th in the warm Pacific Ocean.


But it was a geek.

A Lil known engineer who saved the Mission during the critical Powered descent of the lunar Module.
Member Since: July 3, 2005 Posts: 423 Comments: 127807
Lunch time logins?



Member Since: September 23, 2005 Posts: 14 Comments: 11063
Quoting ElConando:


One upgrade at a time MH, but I know you know that.
Sorry had to get out as the entire weather underground site was down for a couple of seconds. (Crazy that that happened over an invest). But yes, I was just putting out the fact that all intensity models forecast 97L to become a TS. We'll know soon enough if they verify...
Member Since: September 2, 2009 Posts: 130 Comments: 21109
GOOD NWS VIRGIN ISLANDS/ANTILLES RADAR LINK Link
Member Since: July 3, 2007 Posts: 0 Comments: 524
531. MahFL
I got 11 inches of rain from Fay.
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530. xcool





wunderground go off line
Member Since: September 26, 2009 Posts: 2 Comments: 15648
529. SLU


Impressive African wave but the models aren't interested in it although conditions don't look that bad ahead of it.
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An area in the Pacific looks like it may develop.
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What occurred is commonly called "Clock Drift"

..the Server will do that when they working on it in San Fran Sometimes.
Member Since: July 3, 2005 Posts: 423 Comments: 127807
Quoting helove2trac:
come on 97L everyone is pulling for you
NOT.
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GOM 84 Hour Wave Forecast (using MIKE21) Model
Member Since: July 3, 2005 Posts: 423 Comments: 127807
Was the site down just a few moments ago? lol
I think too many ppl clicking on here causing server to get headache, too much clicking on the comments page
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Hey! Anybody out there get an "overload" message on the site about 5 min ago?
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wunderground was overloaded lol,
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Quoting MiamiHurricanes09:
It looks like it may be stronger than a TD if every single model verifies. (Yes every single intensity model (12z) takes 97L to a TS).



One upgrade at a time MH, but I know you know that.
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Sheesh...

LOL
Member Since: July 3, 2005 Posts: 423 Comments: 127807
Quoting Goldenblack:
LOL, yeah....I think there is a definite reason that Fay "intensified" over FL in 2008...



Yeah. They had to stop with the weather modification stuff
as soon as she made landfall.
Member Since: July 3, 2007 Posts: 0 Comments: 524
NASA MSFC Viewer 97L
Member Since: July 3, 2005 Posts: 423 Comments: 127807
515. unf97
Quoting Hurricanes101:


SAL is not very prevelant in the area, that wave looks like it will not have to deal with it


The SAL looks to be waning. I think that wave emerging now off the African coast may have a decent chance in the coming days to possibly develop.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
Quoting patrikdude2:


This model keeps the system parallel to the Florida coast.

Almost seems like 97L likes to "HUG" Florida.


I think this happens only if the ridge of pressure get's stronger and that the system rapidly intensifies around the Bahamas
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Quoting SavannahStorm:
Impressive wave, but I hope it likes...


RIPs and SALsa.



It wont have to deal with SAL.
Member Since: July 6, 2010 Posts: 113 Comments: 31883
Quoting TropicalNonsense:


Fay in 2008 actually made 4 landfalls as a 65 mph Tropical Storm remember?


Oh I almost forgot about Fay... that really was a strange storm - she struck about a week before Gustav started spinning up in the Caribbean...
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97L looks wayy better then TD2 ever did LOL
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This model keeps the system parallel to the Florida coast.

Almost seems like 97L likes to "HUG" Florida.
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485. Picasso would be proud sir!
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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:




Yes, the banding has gotten quite pronounced and it looks better. If it can muster an LLC I would think TD wouldn't be far off.
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Quoting ElConando:


This becomes at least a TD it could have the chance to become the first TC to strike South Florida from the east coast since special K.
It looks like it may be stronger than a TD if every single model verifies. (Yes every single intensity model (12z) takes 97L to a TS).

Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting ElConando:


This becomes at least a TD it could have the chance to become the first TC to strike South Florida from the east coast since special K.


Fay in 2008 actually made 4 FLA landfalls as a 65 mph Tropical Storm remember?
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting SavannahStorm:
Impressive wave, but I hope it likes...


RIPs and SALsa.



SAL is not very prevelant in the area, that wave looks like it will not have to deal with it
Member Since: March 10, 2010 Posts: 1 Comments: 7505
Quoting MiamiHurricanes09:
ASCAT showed that the vigorous tropical wave off the African coast is accompanied by an area of low pressure.

Those wind very strong off the coast of africa, some in access of 40 knots, i wonder how accurate that pass is?
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Gulf and Tropics (Updated every ~1/2 hour)
Member Since: July 3, 2005 Posts: 423 Comments: 127807
Impressive wave, but I hope it likes...


RIPs and SALsa.

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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.'????


But how much rain did he get?
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Quoting Seamule1:
excellent outflow, cdo beginning to explode around the mid level circ. features definitely show a nice evolving system. hate to use words like depression,...but this will be a hurricane in 36 hours or less...and a cat 3-5 before punishing some happless area in the northern gulf coast...

imho


For a second I thought you were stormtop but then again there is nothing humble about his posts.
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C-23 Sherpa (Catfish) over flight oil recon of the Source...

Just wanted to share.









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12z Early Cycle NHC model tracks
Invest97
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)



Member Since: July 3, 2005 Posts: 423 Comments: 127807
Quoting Patrap:






I have a feeling the shear is moving north a bit faster allowing the conditions in the Caribbean to rise over the Islands and where 97L is at. After looking at those images, I'm eager to see if the shear map shows the shear rising northward, away from 97L. Really doesn't look like shear is taking much of an effect at all.
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Quoting germemiguel:
KABOUMMMMM




Could you send me the link on where you got that pass?
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Quoting CaribbeanIslandStorm:
1998 Atlantic hurricane season similar to 2010
Season summary map
First storm formed: July 27, 1998 (1998-07-27)
Last storm dissipated: December 1, 1998
Strongest storm: Mitch – 905 mbar (hPa) (26.74 inHg), 180 mph (285 km/h)
Total storms: 14
Hurricanes: 10
Major hurricanes (Cat. 3+): 3
Total fatalities: Over 12,000
Total damage: $12.2 billion (1998 USD)
$16 billion (2010 USD)


how can you compare this year to '98? im just curious.

weve not seen much of anything yet. But the fireworks
are beginning im pretty sure.
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting stillwaiting:
HJ,Oz,Doug....I'll be on standby for a chase later this week!!!!


Great! Let's use the website and email for coordination.
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This becomes at least a TD it could have the chance to become the first TC to strike South Florida from the east coast since special K.
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excellent outflow, cdo beginning to explode around the mid level circ. features definitely show a nice evolving system. hate to use words like depression,...but this will be a hurricane in 36 hours or less...and a cat 3-5 before punishing some happless area in the northern gulf coast...

imho
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Yeah, probably would have been recieved as well there as it would have been here.
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LOL, yeah....I think there is a definite reason that Fay "intensified" over FL in 2008...

Quoting FLdewey:


Nah the high mountains of Florida will tear it apart. We've got landfills that reach tens of feet into the sky. ;)
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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.

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