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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Quoting 558. LargoFl:
potential hurricane if the gfs proves true...
NOOOOOOOOOOOOOOOOOOO!!!
Member Since: March 12, 2013 Posts: 12 Comments: 19963
Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 18:18Z
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: 19

18:18:30Z 19.233N 85.817W 977.0 mb
(~ 28.85 inHg) 280 meters
(~ 919 feet) 1008.7 mb
(~ 29.79 inHg) - From 168° at 2 knots
(From the SSE at ~ 2.3 mph) 23.3°C
(~ 73.9°F) 23.0°C
(~ 73.4°F) 3 knots
(~ 3.4 mph) 7 knots
(~ 8.0 mph) 0 mm/hr
(~ 0 in/hr) 4.7 knots (~ 5.4 mph)
233.3%
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 18:09:00Z (first observation), the observation was 119 miles (191 km) to the SSE (149°) from Cancún, Quintana Roo, México.

At 18:18:30Z (last observation), the observation was 148 miles (238 km) to the SSE (153°) from Cancún, Quintana Roo, México.
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Quoting 550. daddyjames:


At the very least, an overly aggressive forecast. This will be lucky if it reaches a high end TS.


Something like an Isaac clone...

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maybe a tropical storm soon.
Member Since: March 12, 2013 Posts: 12 Comments: 19963
It may be too early to make substantial preparations along the Gulf Coast. However, FSU is playing Maryland in Tallahassee at noon. They may want to rethink that idea. Stay tuned........
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Quoting 553. StormTrackerScott:


It's probably close to that now. Again look!



The entire eastern part of the convection is not associated with the llc - and will not be wrapped into it. It is being cast off to the north, and will not play a factor in the storm which is located to the SE. The storm itself is very small right now compared with the convection observed. IMHO.
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Quoting 553. StormTrackerScott:


It's probably close to that now. Again look!



Lol. You're steadily losing credibility with this system with each key stroke. It only has 10-20kt winds at flight level on the northern part of the system.

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potential hurricane if the gfs proves true...
Member Since: August 6, 2011 Posts: 4 Comments: 37793
Quoting 545. StormTrackerScott:


This thing is going to be a hurricane soon and maybe a very intense one at that. People better be prepared as this heads north.

Looking like and eye feature developing as thunderstorms wrap around the center. This leads me to believe we already have Karen and she is intensifying right now.

I will refrain from exclamatory phrasing and simply inquire as to your reasoning for the above intensity forecast?
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The chances of this becoming a hurricane, much less a very intense one, are less than 20% if you ask me....
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Bouy 42056
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LMAO LMAO LMAO an eye feature omg WISHCASTER STORMTRACKSCOTT!
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Quoting 550. daddyjames:


At the very least, an overly aggressive forecast. This will be lucky if it reaches a high end TS.


It's probably close to that now. Again look!

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Very weak winds on the north side of the system.

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19.5/85 or so, that's my guess




Doesn't quite look aligned with mlc just yet.
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Quoting 545. StormTrackerScott:


This thing is going to be a hurricane soon and maybe a very intense one at that. People better be prepared as this heads north.


At the very least, an overly aggressive forecast. This will be lucky if it reaches a high end TS.
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Quoting 545. StormTrackerScott:


This thing is going to be a hurricane soon and maybe a very intense one at that. People better be prepared as this heads north.


Lol. Excuse me while I spew out my drink from laughter...
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Looking ahead 3-4 days, the storm will likely get entangled with a mid-latitude trough in the northern Gulf, which would keep it weak, but actually enhance the forecast rainfall totals along the northern Gulf coast. Over the next week, estimates in excess of the 2 inch range cover a large area. Peak totals of over 6 inches are already anticipated near the center.
Member Since: August 6, 2011 Posts: 4 Comments: 37793
Quoting 545. StormTrackerScott:


This thing is going to be a hurricane soon and maybe a very intense one at that. People better be prepared as this heads north.
stop scaring people damn dude, it will be a TS at best. my old prediction of TD at best might be wrong. but this wont be a powerful cane man
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No winds.


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Quoting 538. Patrap:


This thing is going to be a hurricane soon and maybe a very intense one at that. People better be prepared as this heads north.

Looking like and eye feature developing as thunderstorms wrap around the center. This leads me to believe we already have Karen and she is intensifying right now.

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Good evening from still sunny but in the nights chilly Germany. While waiting for Recon data from (still) 97L here are the two weather videos on BBC today:

Cold plunge for North America
2 October 2013 Last updated at 16:24
Alex Deakin takes a look at the stormy weather and potential for snow in parts of North America this week.

Warnings as torrential rain on the way
2 October 2013 Last updated at 13:56
Heavy rain for much of the UK with warnings in force until Thursday, but high pressure fights back bringing settled weather to come for the weekend.
Chris Fawkes takes a more detailed look.


You see the bunch of precipitation out in the Atlantic which should be drawn into the UK tomorrow.
Member Since: October 25, 2008 Posts: 53 Comments: 5904
Quoting 538. Patrap:


Very obvious LLC on that loop. This has to be at least a TD right now
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This might help people understand the timing of the turn east.


Link
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Product: Air Force High Density (HDOB) Message (URNT15 KNHC)

Transmitted: 2nd day of the month at 18:08Z
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: 18

18:08:30Z 19.700N 85.867W 977.2 mb
(~ 28.86 inHg) 278 meters
(~ 912 feet) 1008.6 mb
(~ 29.78 inHg) - From 78° at 3 knots
(From the ENE at ~ 3.4 mph) 23.0°C
(~ 73.4°F) 22.8°C
(~ 73.0°F) 3 knots
(~ 3.4 mph) 5 knots
(~ 5.8 mph) 0 mm/hr
(~ 0 in/hr) 5.0 knots (~ 5.8 mph)
166.7%
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 17:59:00Z (first observation), the observation was 90 miles (145 km) to the SE (137°) from Cancún, Quintana Roo, México.

At 18:08:30Z (last observation), the observation was 118 miles (190 km) to the SSE (148°) from Cancún, Quintana Roo, México.
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Cayman Island Port.. not a great day for these cruise pax...
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Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 17:58Z
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: 17

17:58:30Z 20.217N 85.883W 977.2 mb
(~ 28.86 inHg) 279 meters
(~ 915 feet) 1008.7 mb
(~ 29.79 inHg) - From 93° at 11 knots
(From the E at ~ 12.6 mph) 23.5°C
(~ 74.3°F) 22.8°C
(~ 73.0°F) 11 knots
(~ 12.6 mph) 10 knots
(~ 11.5 mph) 0 mm/hr
(~ 0 in/hr) 10.0 knots (~ 11.5 mph)
90.9%
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 17:49:00Z (first observation), the observation was 74 miles (119 km) to the ESE (115°) from Cancún, Quintana Roo, México.

At 17:58:30Z (last observation), the observation was 89 miles (143 km) to the SE (136°) from Cancún, Quintana Roo, México.
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Quoting 498. MississippiWx:


Lol. When do you not aim anything in the NW Caribbean to that part of Florida? Surprise surprise.


For one I don't live there if that is what you are implying as I live in Orlando and 2 that as been the trend lately with system coming from the NW Caribbean in October & June i.e Andrea.
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http://www.goes.noaa.gov/HURRLOOPS/gulfwv.html

you can very clearly see the edge of the subtropical ridge on the gulf water vapor loop. florida peninsula is safe. I agree with the almost due north w/ slight west track to landfall. afterward hooking east almost 45 degrees.
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For the moment it looks like it will follow the low SE Conus.... Until the front comes along...

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DANG U! Y U GO SO SLO!!!!

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ALERT ATCF MIL 97X XXX 131002120000
2013100212
18.1 274.7
21.7 272.4
100
18.1 274.7
021800
1310021800
2
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
WTNT21 KNGU 021800
RMKS/1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE
WITHIN 100 NM EITHER SIDE OF A LINE FROM 18.1N 85.3W TO 21.7N 87.6W
WITHIN THE NEXT 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF
A NUMBERED TROPICAL CYCLONE WARNING AT THIS TIME. SATELLITE IMAGERY
AT 021700Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 18.1N 85.3W. THE SYSTEM IS MOVING NORTHWESTWARD AT 08 KNOTS.
2. REMARKS: CURRENT MODEL GUIDANCE IS SUGGESTING INTENSIFICATION OF A
TROPICAL DISTURBANCE CURRENTLY LOCATED IN THE NORTHWESTERN CARIBBEAN
SEA. SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT A WEAK
LOW LEVEL CIRCULATION IS EVIDENT. OVER THE PAST 12 HOURS DEEP
CONVECTION REMAINS PERSISTENT OVER THE AREA. WARM SEA SURFACE
TEMPERATURES OF 82 TO 85 DEGREES ALONG WITH A DEEP THERMAL LAYER WILL
AID IN FURTHER DEVELOPMENT. HOWEVER, MID TO UPPER LEVEL DRY AIR TO
THE NORTHWEST ALONG WITH HIGH WIND SHEAR VALUES OF 20 TO 30 KNOTS
WILL LIKELY HINDER ANY STRONG DEVELOPMENT OVER THE NEXT FEW DAYS.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO A WARNING OR CANCELLED
BY 031800Z.//9713092806 126N 747W 20
9713092812 129N 751W 20
9713092818 132N 755W 20
9713092900 134N 758W 20
9713092906 136N 762W 20
9713092912 138N 767W 20
9713092918 139N 774W 20
9713093000 140N 781W 20
9713093006 141N 789W 20
9713093012 144N 796W 25
9713093018 148N 803W 25
9713100100 153N 811W 25
9713100106 158N 818W 25
9713100112 163N 825W 25
9713100118 168N 831W 25
9713100200 173N 840W 25
9713100206 178N 848W 25
9713100212 181N 853W 2
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Quoting 520. nrtiwlnvragn:


GFS not far off of the cyclone models




It will be interesting to see if the GFS bias of being overly progressive with troughs occurs again here. HWRF and GFDL have a lot of input from the GFS, so this makes sense.
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Quoting 505. KEEPEROFTHEGATE:
T.C.F.A.
97L/XX/XX/XX



Looks to me that this one is becoming big and bad enough, at least in saturating it's own environment, to make it's own rules if it so desires.
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The current anti-cyclone helped with the development today but the system is headed towards 30 knots of sheer, currently, on the other side of the Yucatan peninsula in the lower Gulf:

Link

Will be interesting to see, if the system does close off later today or this evening how the models and NHC handle the intensity forecast in the Gulf and what sheer conditions emerge on Friday and Saturday.

It's lonely out there in the Gulf between the sheer and very dry air.............
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Quoting 523. IKE:
Can someone provide a link to recon data?


Link
Member Since: September 23, 2005 Posts: 14 Comments: 11027
Quoting 517. SuperStorm093:
not great conditions for major strengthening in gulf as you can see from the heat content. its in the hottest waters it should be its entire time.


It's all about the upper level environment. Water temps are plenty warm to produce major hurricane.
Windshear and dry air are its greatest enemy.
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Quoting 519. Tribucanes:
Wow named storm #11 coming and the first to be a potential threat to the USA since very early season, and to think the blog made it to this point without implosion. Blog has handled this disappointing season well, and I believe there's been less serious bickering than in busy seasons past. This system seems to be forming more quickly than forecast and with the anticyclone attached it might not be very adversely affected by the moderate shear and with it's potential size it might have enough moisture to counteract the dry air in the Gulf. Anyone believe this may be more in the 60-80mph TS/low end cane potentially?
Yep.
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523. IKE
Can someone provide a link to recon data?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting 518. ChillinInTheKeys:


Obviously a cyclonic wormhole...
And to think we are all grownups
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521. IKE
12Z GFDL @ 60 hours....


Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting 484. MississippiWx:
12z GFDL ensembles:



Operational GFS is the extreme east of any guidance, even well to the east of its own ensembles. GFS track likely to not verify.


GFS not far off of the cyclone models


Member Since: September 23, 2005 Posts: 14 Comments: 11027
Wow named storm #11 coming and the first to be a potential threat to the USA since very early season, and to think the blog made it to this point without implosion. Blog has handled this disappointing season well, and I believe there's been less serious bickering than in busy seasons past. This system seems to be forming more quickly than forecast and with the anticyclone attached it might not be very adversely affected by the moderate shear and with it's potential size it might have enough moisture to counteract the dry air in the Gulf. Anyone believe this may be more in the 60-80mph TS/low end cane potentially?
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Quoting 461. csmda:
Why does this thing look so small on models but right now it's pretty darn big?

And yes, I am al gore, I invented the internet and I know my join date says 1970.


Obviously a cyclonic wormhole...
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not great conditions for major strengthening in gulf as you can see from the heat content. its in the hottest waters it should be its entire time.
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Quoting 473. Sfloridacat5:
GFS 93 hours


almost on top of me...50 miles due north of panama city...I really doubt this, my thinking is mobile bay-Pensacola area. there is a small ull just west of 97 and there is another low in Mississippi that will pull 97 north
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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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