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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Angle and conditions are not right IMO. I think this time we have a strengthening high, not a high that is maintaining or shifting east with time.

Quoting ClearH2Ostormchaser:
Hey StormW. Real quick question if the models shift left a little could land break up the system and if not will it be strong enough to take the infamous "Charley right Hook".
Member Since: Posts: Comments:
Quoting CybrTeddy:
Hey pat, happy moon landing day. 41 years ago today..
Thanks , happy moon u2
Member Since: July 20, 2010 Posts: 0 Comments: 225
Quoting StormW:
Model guidance should shift slightly left next run.


Storm,
Do you think that their is any real chance that the mess (albeit small) headed towards the gulf just below the Yucatan might pull a fast one once it seperates a little farther from 97L? Seems like it would potentially make it to someones front door quicker than 97L dependiung on location (Mexico or Texas, Louisiana could be a tossup though)
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Quoting MiamiHurricanes09:
Satellite imagery suggests that 97L is forming banding, along with improved outflow. 15:00 UTC graphical updates shows that the strongest 925mb vorticity is located right where we want it, north of the eastern tip of the Dominican Republic. At 2PM 97L should be coded red.




97L Giving all it's got to make it to TD Status.
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Quoting BahaHurican:
LOL I'll never forget the 1st time I saw the landfill in NBRoward... I was like "WHAT???? there's a HILL in SF!!!!!" and I was calmly informed by the driver of the car I was in, "Oh, that's just the landfill." First place I know where the highest point in the county is, disputably, a pile of garbage... lol

Now, as a point of storm safety, I don't think hanging out on the landfill is a good idea as a way of getting away from the hurricane.... lol
Lol , i live 2 minutes away from the garbage mountain, XD
it smells bad at times :(
Member Since: July 20, 2010 Posts: 0 Comments: 225
StormW, Would that be because of the impending strength of the High Pressure expected to build in behind the exiting TUTT?

Quoting StormW:
Model guidance should shift slightly left next run.
Member Since: Posts: Comments:
Hey StormW. Real quick question if the models shift left a little could land break up the system and if not will it be strong enough to take the infamous "Charley right Hook".
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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)



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Quoting StormW:
Model guidance should shift slightly left next run.
how much farther left and why storm
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578. 7544
bonnie may be born as early as tonight ie97l

has the pres. drop again ?
Member Since: May 6, 2007 Posts: 0 Comments: 6874
Strongest 925mb vorticity is nestled under deep convection just north of the eastern tip of the Dominican Republic.

Member Since: September 2, 2009 Posts: 130 Comments: 21194



Hurricane Preparation 2010
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Quoting StormW:
Model guidance should shift slightly left next run.



When you say left .. you mean South right Storm?
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting Ameister12:
Good afternoon.

You guys in Florida ready for your first storm of the season.



As long as it's just a storm, yes, we need the rain badly.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting CyclonicVoyage:


Most importantly, it's no longer a wave.
Exactly!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Yeah, I think you always have to be here in Florida.....bet we are not as ready as Louisiana and Texas (because of more recent events)

Quoting Ameister12:
Good afternoon.

You guys in Florida ready for your first storm of the season.
Member Since: Posts: Comments:
571. xcool
HERE WE GOO .
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Satellite imagery suggests that 97L is forming banding, along with improved outflow. 15:00 UTC graphical updates shows that the strongest 925mb vorticity is located right where we want it, north of the eastern tip of the Dominican Republic. At 2PM 97L should be coded red.



Member Since: September 2, 2009 Posts: 130 Comments: 21194
Wave O Doom - starring Harrison Ford....

Really starting to get active out there

Quoting Patrap:
Wave O Doom ?

Healthy Pup there.

Let see what it looks like in 30-36
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Good afternoon.

You guys in Florida ready for your first storm of the season.
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Quoting Jeff9641:


Here comes 98L.
and 99L after next wave from Africa
Member Since: July 20, 2010 Posts: 0 Comments: 225
Quoting Patrap:


I leave the cartoons to them to my East..

LOL


I'm not that far east thank goodness.....LOL
Member Since: September 1, 2007 Posts: 0 Comments: 1793
Quoting Drakoen:
Very vigorous wave with an evident low level circulation is moving off the coast of Africa:



There is another 1 behind it lol it's a choo choo train
Member Since: July 20, 2010 Posts: 0 Comments: 225
Quoting CybrTeddy:
Mornin pat, happy moon landing day. 41 years ago today..


U betcha..

Coming Down at 6..drifting to the Right a Lil..
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Hey pat, happy moon landing day. 41 years ago today..
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Quoting MiamiHurricanes09:
Happened here too. And that was just an invest, any ideas what will happen when there's a category 5?
Category Five Hurricane (Sustained winds greater than 155 mph, greater than 135 kt, or greater than 249 km/hr).
Catastrophic damage will occur
People, livestock, and pets are at very high risk of injury or death from flying or falling debris, even if indoors in mobile homes or framed homes. Almost complete destruction of all mobile homes will occur, regardless of age or construction. A high percentage of frame homes will be destroyed, with total roof failure and wall collapse. Extensive damage to roof covers, windows, and doors will occur. Large amounts of windborne debris will be lofted into the air. Windborne debris damage will occur to nearly all unprotected windows and many protected windows. Significant damage to wood roof commercial buildings will occur due to loss of roof sheathing. Complete collapse of many older metal buildings can occur. Most unreinforced masonry walls will fail which can lead to the collapse of the buildings. A high percentage of industrial buildings and low-rise apartment buildings will be destroyed. Nearly all windows will be blown out of high-rise buildings resulting in falling glass, which will pose a threat for days to weeks after the storm. Nearly all commercial signage, fences, and canopies will be destroyed. Nearly all trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Long-term water shortages will increase human suffering. Most of the area will be uninhabitable for weeks or months. Hurricane Andrew (1992) is an example of a hurricane that brought Category 5 winds and impacts to coastal portions of Cutler Ridge, Florida with Category 4 conditions experienced elsewhere in south Miami-Dade County.

From NHC.
Member Since: July 20, 2010 Posts: 0 Comments: 225
Quoting MiamiHurricanes09:
Yep. Pressure down 1mb and winds up 5kt. I assume that at 18z the pressure will be at 1012 or lower.


Most importantly, it's no longer a wave.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting FLdewey:


Nah the high mountains of Florida will tear it apart. We've got landfills that reach tens of feet into the sky. ;)
LOL I'll never forget the 1st time I saw the landfill in NBRoward... I was like "WHAT???? there's a HILL in SF!!!!!" and I was calmly informed by the driver of the car I was in, "Oh, that's just the landfill." First place I know where the highest point in the county is, disputably, a pile of garbage... lol

Now, as a point of storm safety, I don't think hanging out on the landfill is a good idea as a way of getting away from the hurricane.... lol
Member Since: Posts: Comments:
Wave O Doom ?

Healthy Pup there.

Let see what it looks like in 30-36
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Very vigorous wave with an evident low level circulation is moving off the coast of Africa:



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Quoting StormSurgeon:


I thought it was because you were drawing lines on a sat. image and triple posting it.


I leave the cartoons to them to my East..

LOL
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549. xcool
Looking much better.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting MahFL:
I got 11 inches of rain from Fay.


yes, there was severe flooding because she took her sweet little time moving across the florida peninsula! Fay was messed up. LOL
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting CyclonicVoyage:
AL, 97, 2010072012, , BEST, 0, 190N, 658W, 30, 1013, DB,
Yep. Pressure down 1mb and winds up 5kt. I assume that at 18z the pressure will be at 1012 or lower.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Looks like all 6 models have this at a TS/Hurricane with 3 putting it back into the Gulf after hitting Mexico.

Im praying for all my bro's and sis's in the path.
Member Since: July 12, 2010 Posts: 0 Comments: 235
jeesum..


B-4 ya post a question,,read back some
The answer just may be staring bac atcha.

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Quoting Patrap:
What occurred is commonly called "Clock Drift"

..the Server will do that when they working on it in San Fran Sometimes.


I thought it was because you were drawing lines on a sat. image and triple posting it.
Member Since: September 1, 2007 Posts: 0 Comments: 1793
Quoting BahaHurican:
Hey! Anybody out there get an "overload" message on the site about 5 min ago?
Happened here too. And that was just an invest, any ideas what will happen when there's a category 5?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
541. unf97
Quoting MahFL:
I got 11 inches of rain from Fay.


I received 14 inches from T.S. Fay in North Jax.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
AL, 97, 2010072012, , BEST, 0, 190N, 658W, 30, 1013, DB,
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting BahaHurican:
Hey! Anybody out there get an "overload" message on the site about 5 min ago?

I got "Failure to Connect with Web Server".
Member Since: Posts: Comments:


Puerto Rico and nearby islands have been taking a beating from this storm LOL , i think it finally is beginning to move north westward
Member Since: July 20, 2010 Posts: 0 Comments: 225

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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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