97L in Western Caribbean Still a Threat to Develop

By: Dr. Jeff Masters , 1:58 PM GMT on October 02, 2013

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A tropical disturbance (Invest 97L) over the Western Caribbean is moving to the northwest at 10 mph and is generating heavy rains over the Cayman Islands and Western Cuba. Grand Cayman Island had picked up 2.32" (59 mm) of rain as of 9:30 am EDT on Wednesday. Satellite loops show that 97L has a modest area of heavy thunderstorms that have increased substantially in areal coverage and in intensity since Tuesday, but there is little rotation apparent. Cayman Islands radar also does not show any rotation to the echoes, but there are several prominent low-level bands of heavy rain. The storm has low wind shear of 5 - 10 knots to work with, as well as an upper-air anticyclone aloft that is providing good ventilation above it. Dry air is over the Yucatan Peninsula and Gulf of Mexico, as seen on water vapor satellite loops, and this dry air is slowing development. Ocean temperatures are a very warm 29°C (84°F). An Air Force hurricane hunter flight is scheduled for Wednesday afternoon.


Figure 1. Wind forecast for 2 pm EDT Saturday October 5, 2013, from runs of the GFS model done six hours apart. The more recent run, initialized at 06Z (2 am EDT) on Wednesday, October 2 (left panel) predicts that 97L will have top winds below 35 knots (40 mph, light orange colors). This run showed the center of 97L making landfall in the Florida Panhandle about 120 miles east of Alabama late Saturday afternoon.The run initialized six hours earlier, at 00Z (right panel), showed a stronger storm, with top winds of 40 - 45 knots (46 - 52 mph.) This run showed the center of 97L making landfall near the Alabama/Florida border Saturday night. The images were generated using our wundermap with the model layer turned on.

Forecast for 97L: development into at least a tropical depression likely
Wind shear is expected to remain low on Wednesday, then steadily increase to the moderate range on Thursday, then to the high range on Friday, according to the latest SHIPS model forecast. On Wednesday night, 97L will cross the northeastern tip of Mexico's Yucatan Peninsula, bringing 3 - 6" of rain to the peninsula and to Western Cuba. Passage over the Yucatan will act to disrupt the storm. The atmosphere will grow drier as 97L moves northwards over the Gulf of Mexico on Thursday and Friday, and the drier air combined with increasing wind shear will retard development, making rapid intensification unlikely. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn 97L more to the northeast as it approaches the coast on Friday. The GFS model develops 97L into a tropical storm, and predicts landfall will occur along the Florida Panhandle. The European model, which does not develop 97L into a tropical storm, is farther west, taking the storm over Eastern Louisiana. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 97L 2-day odds of development of 40%, and 5-day odds of 50%. I give a 30% chance 97L will be Tropical Storm Karen with top winds of 40 - 60 mph at landfall between Louisiana and the Florida Panhandle on Saturday, a 5% chance it will be stronger, and a 65% chance it will be a tropical depression or mere tropical disturbance. Heavy rains of 3 - 6" can be expected falling the coast from Louisiana to the Florida Panhandle on Saturday, even if 97L does not develop into a tropical depression.


Figure 2. MODIS satellite image of 97L, taken at 12:30 pm EDT on October 2, 2013. Image credit: NASA.

Tropical Storm Jerry in the Central Atlantic no threat
Tropical Storm Jerry continues to slowly wander over the Central Atlantic, far from land. Jerry is not a threat to any land areas.

Jeff Masters

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1416. will40
im beginning to wonder if it has closed off the center
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1415. GatorWX
MSwx, give it a rest will ya??
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Member Since: May 23, 2012 Posts: 0 Comments: 4691
1411. bwi
Winds still 25-30kt at the buoy -- SSE. 1008mb this hour, which is up a smidge. 19.8n 84.9 w

The storm center is actually pulling away a bit to the north and west now.
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1410. Broward
Quoting 1337. VR46L:
Looks like the mid west has more to worry about in this run of the Gfs



man canadian air could travel all the way to the gulf..nice pressure gradient too
Member Since: September 22, 2004 Posts: 1 Comments: 181
Quoting 1404. MAweatherboy1:
The 18z GFS also shows whatever becomes of 97L eventually being a soaking rainstorm for the whole East Coast:



This well worth it!.Notice a storm in the MDR.
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1408. Patrap

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 22:08Z
Date: October 2, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 301)
Mission Purpose: Investigate sixth suspect area (flight in the North Atlantic basin)

Mission Number: 1

Observation Number: 42

22:08:30Z 20.333N 86.050W 977.0 mb
(~ 28.85 inHg) 265 meters
(~ 869 feet) 1007.0 mb
(~ 29.74 inHg) - From 307° at 5 knots
(From the NW at ~ 5.8 mph) 23.4°C
(~ 74.1°F) 22.7°C
(~ 72.9°F) 5 knots
(~ 5.8 mph) 22 knots
(~ 25.3 mph) 7 mm/hr
(~ 0.28 in/hr) 22.0 knots (~ 25.3 mph)
440.0%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 21:59:00Z (first observation), the observation was 99 miles (159 km) to the SE (131°) from Cancún, Quintana Roo, México.

At 22:08:30Z (last observation), the observation was 76 miles (122 km) to the SE (138°) from Cancún, Quintana Roo, México.
Member Since: July 3, 2005 Posts: 426 Comments: 128764
1407. Patrap
Dvorak Loop 97L
Member Since: July 3, 2005 Posts: 426 Comments: 128764
Quoting 1396. PcolaSurf182:


He'll come to Pensacola Beach. He's made friends with one of our local mets here. Seen them hanging out at one of our local beach bars a few times! Who doesn't like a 151 Bushwacker? Ha

Hey I know I do that's for sure.... Been there many times my self.... :o)

Taco :o)
Member Since: July 7, 2005 Posts: 6 Comments: 3261
Quoting 1399. HighTideNPcola:

"Ha Ha Ha!!"  .....what would you do all day if you didn't have the joy of correcting everyone on this forum to boost your self righteous ego?   My God please stop it.  I

I what?
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The 18z GFS also shows whatever becomes of 97L eventually being a soaking rainstorm for the whole East Coast:



Member Since: February 11, 2012 Posts: 83 Comments: 7839
No effects on the east coast...for West Palm Beach...

Member Since: September 10, 2007 Posts: 0 Comments: 11283
If this system is not moving quickly expect the Models to shift to the right or East tomorrow,in my opinion this could be a surprise Storm,even thought all models shows a Northerly Track,we are in October and usually it will turn NE,the slow motion might catch up with the strong front coming down when this thing is probably in the middle of the Gulf of Mexico and push it toward the West Coast of Central Florida,and with all the nasty weather to the East of the system,Florida is up for some very rainny and stormy weather in the next few days (here in Miami is non-stop rain and storms, a lot of flooding).
And I agreed it have all the ingredients to become a major storm,just look at at the size and outflow!! truly amazing!!.I don't know how to read the Hurricane Hunter numbers but what they said about wind speed,location of the center and motion (how fast is moving in any)?.
Member Since: August 28, 2006 Posts: 0 Comments: 624
1400. LargoFl
7-day for Tampa bay area..rain chances dropping again..
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Quoting 1385. taco2me61:
Ok does Jim Cantore go to Panama City Beach or does he go to Pensacola Beach????

Taco :o)


I PRAY we won't be subjected to watching JC and worse yet...Mike Seidel stand in the sand and "rant" about the rain, wind and sand in their faces!! Lord!!
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Problem with the models is their initializing the low too far to the west and has it going over the Yucatan Peninsula. I think it shoots the gap.

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Quoting 1385. taco2me61:
Ok does Jim Cantore go to Panama City Beach or does he go to Pensacola Beach????

Taco :o)


He'll come to Pensacola Beach. He's made friends with one of our local mets here. Seen them hanging out at one of our local beach bars a few times! Who doesn't like a 151 Bushwacker? Ha
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1395. hydrus
Water Vapor.

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Quoting 1373. LargoFl:
Local met said how eastward 97 goes depends all on how fast the front comes...


And from what I have read, the front is a slow mover. A faster moving front would make a difference. But that's not in the cards as of this hour.
Member Since: September 10, 2007 Posts: 0 Comments: 11283
Quoting 1356. TropicalAnalystwx13:
Lots of upper-level divergence at landfall.


Karen will likely be Weighted on the eastern side by landfall. You can see it best in that image because there are no wind vectors fanning out on the storms west side indicating westerly shear, at least in the moderate range. Though it may not impact the storm enough to weaken it before landfall, it will likely cause it to top off as it makes landfall.
Member Since: June 2, 2013 Posts: 8 Comments: 1347
1392. LargoFl
Quoting 1382. clwstmchasr:


Hey, I'm out of town. Are the local mets at all worried? I read the Tampa NWS and they have only a 30% chance of rain for us this weekend.
no just casual talk, most think a slightly higher rain chances..so far they said....wont be a wind event for here.
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Contrary to the dry air enthusiasts and numerous naysayers that we saw a couple of days ago, my forecast for this system suggested something quite different, and do you see any land within sight?

I don't, which means at this point, she won't either.

Quoting 834. OracleDeAtlantis:


Post 834 - September 30, 2013 - WeatherUnderground







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NBC News Science

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How to detect pseudo-science
www.nbcnews.com
Climate denial ... creationism ... doomsday predictions ... vaccination warnings: It's all in a day's debunking for Phil Plait

http://t.nbcnews.com/science/how-detect-pseudo-sc ience-b-s-8C11323108
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Quoting 1372. number4steel:
dumb question here .if storms gain strength at dmax and given the current use of avionics, why cant hh's fly into these storms at night to truly monitor thee growth of these storms?



they do fly at night
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Looks like the west coast of Florida could see some action (outer bands)from the system. Panhandle gets a direct stike based on the GFS
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Quoting 1349. GatorWX:


Loving all the cool images! Thx!
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Ok does Jim Cantore go to Panama City Beach or does he go to Pensacola Beach????

Taco :o)
Member Since: July 7, 2005 Posts: 6 Comments: 3261
Quoting 1371. Torito:


AMG TIME WARP. xD

lmao
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1383. Patrap
Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 21:58Z
Date: October 2, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 301)
Mission Purpose: Investigate sixth suspect area (flight in the North Atlantic basin)

Mission Number: 1

Observation Number: 41



21:58:30Z 20.200N 85.650W 977.2 mb
(~ 28.86 inHg) 261 meters
(~ 856 feet) 1006.7 mb
(~ 29.73 inHg) - From 213° at 10 knots
(From the SSW at ~ 11.5 mph) 23.5°C
(~ 74.3°F) 22.9°C
(~ 73.2°F) 10 knots
(~ 11.5 mph) 15 knots
(~ 17.2 mph) 0 mm/hr
(~ 0 in/hr) 15.0 knots (~ 17.2 mph)
150.0%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic
At 21:49:00Z (first observation), the observation was 110 miles (178 km) to the ESE (123°) from Cancún, Quintana Roo, México.

At 21:58:30Z (last observation), the observation was 101 miles (162 km) to the SE (131°) from Cancún, Quintana Roo, México.


Member Since: July 3, 2005 Posts: 426 Comments: 128764
1381. Thrawst
Quoting 1311. CaribBoy:
Man I WANT my big slow moving and wet TS!!


No. You have to earn it.
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1380. will40
Quoting 1372. number4steel:
dumb question here .if storms gain strength at dmax and given the current use of avionics, why cant hh's fly into these storms at night to truly monitor thee growth of these storms?


one is scheduled to take off at 11:00 PM tonight
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Quoting 1372. number4steel:
dumb question here .if storms gain strength at dmax and given the current use of avionics, why cant hh's fly into these storms at night to truly monitor thee growth of these storms?


They fly in at night all the time. Wilma's lowest pressure was recorded at night.
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Quoting 1368. Articuno:

Andrea?
All these storm names start to look at th same when your pressed on the screen for to long.
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Certainly a closer track to the west coast of Florida is not out of the question.
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1376. LargoFl

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
ALABAMA...SOUTHWEST ALABAMA...NORTHWEST FLORIDA AND SOUTHEAST
MISSISSIPPI.

.DAY ONE...REST OF TODAY AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
TODAY ACROSS COASTAL ALABAMA...THE WESTERN FLORIDA PANHANDLE...AND
INLAND SOUTHEAST MISSISSIPPI. STRONG TO SEVERE STORMS ARE NOT
EXPECTED.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

RIP CURRENT RISK INCREASES THROUGH LATE WEEK AND IS FORECAST TO BE
HIGH THROUGH THE WEEKEND.

AN AREA OF DISTURBED WEATHER OVER THE NORTHWEST CARIBBEAN SEA MOVES
NORTH OVER THE NEXT FEW DAYS...APPROACHING THE NORTHERN GULF COAST
REGION BY SATURDAY. RAIN CHANCES INCREASE THIS WEEKEND AS THE LOW
MOVES INTO THE GENERAL AREA AND A COLD FRONT APPROACHES FROM THE
WEST. PERIODS OF HEAVY RAIN ARE POSSIBLE IF THE TRACK OF THE LOW IS
ACROSS OR WEST OF THE LOCAL AREA. IN ADDITION...A PROLONGED EAST TO
SOUTHEAST WIND MAY RESULT IN SOME MINOR COASTAL FLOODING FRIDAY AND
SATURDAY.

OUR BEST ESTIMATION FOR RAINFALL AMOUNTS IS 3 TO 4 INCHES WITH 6 TO
8 INCHES ON A LOCAL BASIS. THESE AMOUNTS WOULD MAINLY BE THE
COASTAL COUNTIES OF ALABAMA AND THE EXTREME WESTERN FLORIDA
PANHANDLE...INCLUDING THE INTERIOR OF THESE COUNTIES FROM EARLY
SATURDAY THROUGH MIDDAY SUNDAY. THESE AMOUNTS ARE SUBJECT TO
CONSTRAINTS OF CURRENT FORECAST UNCERTAINTY AND WILL LIKELY BE
ADJUSTED.

IMMEDIATE COASTAL RESIDENTS CAN ALSO EXPECT MINOR COASTAL FLOODING
IMPACTS AT THE TIME OF BOTH HIGH TIDES FRIDAY AND SATURDAY EVENINGS.
LOW TIDES IN BETWEEN WILL NOT RECEDE THAT MUCH DUE TO PERSISTENT
ONSHORE WINDS.

ALSO FOR THOSE LIVING ON OCEAN-FACING BARRIER ISLANDS EXPECT SOME
WAVE RUN UP TO CAUSE MINOR FLOODING...HIGH WAVES IN THE LOCAL SURF
ZONE AND POTENTIAL MINOR EROSION FROM FRIDAY EVENING TRHOUGH EARLY
SUNDAY.

WIND GUSTS BETWEEN 35 AND 45 MPH ARE POSSIBLE IN COASTAL RAINBANDS
REGARDLESS OF WHETHER THE SYSTEM BECOMES A TROPICAL DEPRESSION OR
STORM.

.SPOTTER INFORMATION STATEMENT...

AREA RESIDENTS AND VISITORS ARE URGED TO MONITOR THE FORECAST OVER
THE NEXT FEW DAYS REGARDING THE POTENTIAL TROPICAL DEVELOPMENT IN THE
GULF.

$$
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Quoting 1365. scottsvb:
97L is having a nice flare up...and that's what we want to see if this is going to develop...but problem is that the LLC is off to it's west...or should I say, trough of low pressure. Winds generally been around 25kt-30kts in the rain squalls..but with the blow up, the HH's found winds in excess of TS that developed in the past few hours. 97L isn't completely closed. This will change tonight into Thurs. Chances of this being a TS by 5am is 50-50 but by 11am will go up to 80%.
97L needs to get the it' own T-Storm blow up near the LLC or get pulled into the blow up to its east. We will just have to watch to see this happen.
Still expecting a TS on Thurs sometime and possibly approaching hurricane strength later Friday night or Saturday. Movement will follow the GFS or maybe slightly east depending on how fast the front comes down and the speed of the near term (24hr) movement of 97L


Yeah, the actual center is west of the big blow up in convection. This thing is still ragged underneath.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
1373. LargoFl
Local met said how eastward 97 goes depends all on how fast the front comes...
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dumb question here .if storms gain strength at dmax and given the current use of avionics, why cant hh's fly into these storms at night to truly monitor thee growth of these storms?
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1371. Torito
Quoting 1368. Articuno:

Andrea?


AMG TIME WARP. xD
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A nice burst of convection could be giving away where a circulation might be trying to set up shop, or it's still weighted in the mid-levels and is disorganized in the low levels, we shall find out soon enough.



Member Since: June 2, 2013 Posts: 8 Comments: 1347
1369. Torito
Quoting 1362. CaribBoy:


LMAO!!


But, it is true..... :/
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Quoting 1364. washingtonian115:
I'm just glad Andrea will be giving me something we've been lacking.The gift of rainfall!.

Andrea?
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Quoting 1356. TropicalAnalystwx13:
Lots of upper-level divergence at landfall.



More like lots of westerly shear.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
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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.