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 connie1976:
...sometimes this blog cracks me up!! You will have people post how an invest is going to be a super storm and hit in there area, but later on say how storms are bad and how they don't want one....but secretly you know they are wishing for the storm to come....the problem is....when once actually does come and they don't have a house or don't have power for a week they will never want a storm again...well, at least until the next year...lol.. ;)


umm .you were doing the same thing earlier..wishing for a storm..cracking up over yourself
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Quoting hydrus:
The water temps this thing will be moving over is high octane for tropical cyclones. I know you know this, but I wanted to say high octane..pfffft

and its not just the water temps this thing can literaly go over crude
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My goodness.....

Link
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Quoting CybrTeddy:


Yes and tomorrow 3 times. It will probably be a TD by 8 pm tomorrow.


Thanks CT.....When is their first run?
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Quoting Tropicaddict:
Are and if so when are the HH supposed to go in?


203

NOUS42 KNHC 201445

WEATHER RECONNAISSANCE FLIGHTS

CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.

1045 AM EDT TUE 20 JULY 2010

SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)

VALID 21/1100Z TO 22/1100Z JULY 2010

TCPOD NUMBER.....10-050



I. ATLANTIC REQUIREMENTS

1. SUSPECT AREA (NORTH OF HISPANIOLA)

FLIGHT ONE -- TEAL 70

A. 21/1800Z

B. AFXXX 01BBA INVEST

C. 21/1400Z

D. 21.0N 70.0W

E. 21/1700Z TO 21/2100Z

F. SFC TO 10,000 FT



FLIGHT TWO -- NOAA 49

A. 22/0000Z

B. NOAA9 02BBA SURV

C. 21/1730Z

D. NA

E. NA

F. 41,000 TO 45,000 FT



FLIGHT THREE -- TEAL 71

A. 22/0600Z, 1200Z

B. AFXXX 0303A CYCLONE

C. 22/0400Z

D. 22.0N 72.0W

E. 22/0500Z TO 22/1200Z

F. SFC TO 15,000 FT



2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF

SYSTEM REMAINS A THREAT. A POSSIBLE G-IV

MISSION FOR 23/0000Z.



II. PACIFIC REQUIREMENTS

1. NEGATIVE RECONNAISSANCE REQUIREMENTS.

2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

JWP


Member Since: July 15, 2006 Posts: 170 Comments: 53536
sorry btwntx08.......my bad. Get this man a cookie too! LOL
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Quoting xcool:
AlexEmmett LOL

yah but i as well said it would be 60 can i have my 1,000 dollars please lol
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Member Since: July 3, 2007 Posts: 0 Comments: 524
Depending on if a closed circulation becomes well defined and if those T-numbers are high enough, we could see a TD as early as tonight.
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Quoting Tropicaddict:
Are and if so when are the HH supposed to go in?


Yes and tomorrow 3 times. It will probably be a TD by 8 pm tomorrow.
Member Since: July 8, 2005 Posts: 259 Comments: 23887
Quoting Floodman:


That is potentially disastrous...
The water temps this thing will be moving over is high octane for tropical cyclones. I know you know this, but I wanted to say high octane..pfffft
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now let's all slow down and analyze this thing...after all...what have we really got here?

a somewhat slow moving tropical system sliding north of the hispaniola area...and slipping towards the keys...in the last part of July....

temperatures in the water are toasty....favorable winds aloft....developing system with no mountains to impeed it...and a better than even chance of slipping into the GOM.....

cat 5 imho.....it will explode well before florida as a cat 2 or so...and then once in the GOM.....uh oh...

see...that wasn't so bad, was it. are we calm now?

landfall between Panama City, and Biloxi, Ms....
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The TWD should be interesting...
Member Since: September 2, 2009 Posts: 130 Comments: 21118
Quoting Ameister12:

They deserve a cookie.

Here you go guys!


chocolate chip cookies.....yum! :)
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918. unf97
Jeff, I saw that run a bit earlier. GFDL has it moving right near Cape Canaveral. I was relectant to mention that because it's still too early, and I am not onboard yet with such a shift northward. But, if the GFDL run verifies, that will have a big impact on conditions in NE FL and Central FL coastline.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
Are and if so when are the HH supposed to go in?
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I think Sarah Palin gets her vocabulary from these posts....I mean...who uses complexe and complexity in the same sentence? Wow, my head is spinning.
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915. xcool
AlexEmmett LOL
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Member Since: October 28, 2006 Posts: 57 Comments: 30181
Quoting Jeff9641:
I'm sure NASA will implement hurricane plans in the next day or so.


Only if a shuttle is on the pad, it will be a pretty significant halt in shuttle processing for STS-133, 134 and 335/135 though, might cause a delay.
Member Since: July 8, 2005 Posts: 259 Comments: 23887
Quoting CybrTeddy:
RED alert man your battle stations!


Red Alert - standing by!!!
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting xcool:
YAY

crap im in florida so this is not cool
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SATELLITE IMAGERY SUGGESTS THAT A SURFACE LOW PRESSURE AREA IS
BECOMING BETTER DEFINED JUST NORTH OF THE EASTERN TIP OF HISPANIOLA
Member Since: September 2, 2009 Posts: 130 Comments: 21118
Member Since: July 15, 2006 Posts: 170 Comments: 53536
Look....

hmmmmm
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AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting xcool:
Hurricanes101 /Everything is up in the air right now..


Agreed. Until atleast a depression forms the models will
have big trouble with this system.
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting jasoniscoolman2010x:
ITS GOING UP TO 50% AT 2PM


You were saying?
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RED alert man your battle stations!
Member Since: July 8, 2005 Posts: 259 Comments: 23887
901. xcool
F555555555555 GET READY
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RED YEAH
899. xcool
YAY
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Quoting TropicalAnalystwx13:
000
ABNT20 KNHC 201740
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE JUL 20 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A VIGOROUS TROPICAL WAVE
EXTEND FROM THE NORTHERN LEEWARD ISLANDS WESTWARD TO HISPANIOLA.
ALTHOUGH THE SYSTEM DOES NOT YET HAVE A CLOSED CIRCULATION...
SATELLITE IMAGERY SUGGESTS THAT A SURFACE LOW PRESSURE AREA IS
BECOMING BETTER DEFINED JUST NORTH OF THE EASTERN TIP OF
HISPANIOLA.
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE FAVORABLE
FOR ADDITIONAL DEVELOPMENT AS THE SYSTEM MOVES WEST-NORTHWESTWARD
AT ABOUT 10 MPH DURING THE NEXT DAY OR SO. THERE IS A HIGH
CHANCE...60 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL DEPRESSION
OR STORM DURING THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT...
LOCALLY HEAVY RAINFALL AND GUSTY WINDS WILL LIKELY AFFECT THE
VIRGIN ISLANDS...PUERTO RICO...THE DOMINICAN REPUBLIC...HAITI...
EASTERN CUBA...THE TURKS AND CAICOS ISLANDS...AND THE SOUTHEASTERN
BAHAMAS DURING THE NEXT COUPLE OF DAYS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.


Miami And Drak nailed it!
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Red it is.....
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Quoting TropicalAnalystwx13:
000
ABNT20 KNHC 201740
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE JUL 20 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A VIGOROUS TROPICAL WAVE
EXTEND FROM THE NORTHERN LEEWARD ISLANDS WESTWARD TO HISPANIOLA.
ALTHOUGH THE SYSTEM DOES NOT YET HAVE A CLOSED CIRCULATION...
SATELLITE IMAGERY SUGGESTS THAT A SURFACE LOW PRESSURE AREA IS
BECOMING BETTER DEFINED JUST NORTH OF THE EASTERN TIP OF
HISPANIOLA. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE FAVORABLE
FOR ADDITIONAL DEVELOPMENT AS THE SYSTEM MOVES WEST-NORTHWESTWARD
AT ABOUT 10 MPH DURING THE NEXT DAY OR SO. THERE IS A HIGH
CHANCE...60 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL DEPRESSION
OR STORM DURING THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT...
LOCALLY HEAVY RAINFALL AND GUSTY WINDS WILL LIKELY AFFECT THE
VIRGIN ISLANDS...PUERTO RICO...THE DOMINICAN REPUBLIC...HAITI...
EASTERN CUBA...THE TURKS AND CAICOS ISLANDS...AND THE SOUTHEASTERN
BAHAMAS DURING THE NEXT COUPLE OF DAYS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

Show me the MOney i called it
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Quoting btwntx08:
12z coordinates are old already and the 18z coordinates will put it more west than before



When you look at the 12Z HWRF @ 18Z you must not look at the initialization point rather, +6 hours to see current location. The 12Z location was correct @ 12Z. Take the 12Z HWRF and fast forward 6 hours and it is more than likely N of the Eastern Tip of DR.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Rather potent tropical wave currently dubbed invest 97L is becoming more organized this afternoon. 850mb vorticity represents a tightening circulation developing and we should soon see this translate to the immediate surface of the ocean by this evening. Wind shear is on the order of 20-30knots according to 1500utc CIMSS shear analysis, although the system seems to be trying to ventillate itself by developing cirrus outflow in the northeastern and eastern sides of the system. The SW side of the system is devoid of any convection likely due to the presence of land interaction with hispaniola. The rather ragged appearance is organizing and looks like a system developing into a tropical cyclone. Ratherly common to see in Atlantic Basin developing cyclones. The circulation seems broad in nature at this time due to the rather disorganized SW semicircle of the system, but 850mb vorticity says the opposite. We likely see here is a distinct MLC circulation center near the north coast of Puerto Rico rather displaced to the east, southeast of the 850mb vort max circulation do to the strong westerly shear presently over the system. Broad outflow is seen, due to the strength of the upper level divergence on top of the cyclone likely aiding in sustained convection while ll convergence is rather meager right now. Until this improves the convection will likely be sustained by the influence of the upper level low to the northwest of the system. Track guidance takes this system on a general WNW heading towards SFL. Some models take it south of the FL through the FL straits or into eastern Cuba do to the presence of the strong SE ridge in place, while the NOGAPS, CMC, GFS (both) take this system into SFL and then into the northeastern GOM. Right now the intensity forecasts are hard to look at given we don't have a real COC as well as a tropical cyclone so the true environmental effects are unknown. At this time I give this system a 50% of becoming a tropical cyclone by 00z Thursday(8pm EDT Wednesday night). Given the dry air to the west, northwest of 97L and the large envelope of shear surrounding the system, especially to the north, I will go for an intensity of 60mph and landfall on SFL by Friday. Right now it is just a guess given the system has yet to organize into a true tropical cyclone.

Large African wave emerging into the Atlantic....

Currently we have a large African wave with an apparent low level circulation according ASCAT pass shown on the blog a few pages ago. Convection seems disjointed somewhat given to the presence of the wave emerging over water and entering a new enviroment as well as a belt of 20 knots of wind shear to the west and effecting the SW quadrant of the system. Right now SAL is not a factor, wind shear is moderate but weakens ahead of the wave's expected path due to the latest 850mb steering currents. These currents all the way up to 200mb takes this system in the general west to west, northwest direction. At this time it is hard to say who needs to watch it, given it is at least 7 days away from affecting the Lesser Antilles, but the steering currents suggest it goes northeast of the Islands. I will have more on this wave this weekend when conditions become more favorable for a more modest strengthening period in which we could have TD 4 or 5 in the making.
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Member Since: July 20, 2010 Posts: 0 Comments: 225
That is so true connie

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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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