Tropical Storm Karen Forms in the Gulf of Mexico

By: Dr. Jeff Masters , 2:09 PM GMT on October 03, 2013

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Hurricane Watches are flying along the U.S. Gulf Coast as Tropical Storm Karen heads north-northwest into the Gulf of Mexico. Karen, the eleventh named storm of the 2013 Atlantic hurricane season, formed about 8 am EDT Thursday in the Southeast Gulf of Mexico. It's not often that one sees a new storm start out with 60 mph sustained winds, but that's what an Air Force hurricane hunter plane found this morning near 7:30 am EDT, when they sampled the northern portion of the storm. A ship located about 50 miles northeast of the northeast tip of the Yucatan Peninsula measured sustained winds of 51 mph near the same time. Satellite loops show that Karen is a medium-sized storm with an area of very intense thunderstorms along its northern and eastern flanks. Wind shear has risen since Wednesday, and is now a moderately high 20 knots, thanks to strong upper-level winds out of the west-southwest. These strong winds are keeping any heavy thunderstorms from developing on the west side of Karen's center of circulation, by driving dry air that is over the Yucatan Peninsula and Western Gulf of Mexico into Karen's core. As a result, Karen has a lopsided comma-shape on satellite imagery. Karen has a strong upper-level outflow channel to its north that is helping ventilate the storm, though, and ocean temperatures are a very warm 29°C (84°F). Between 7 am and 9:30 am EDT the Hurricane Hunters made three passes though the center of Karen, and the central pressure stayed roughly constant at 1004 mb, so Karen is not undergoing much change.


Figure 1. Odds of receiving more than 4" of rain over a five-day period beginning at 2 am EDT Thursday October 3, 2013, as predicted by the experimental GFDL ensemble model.

Forecast for Karen
Wind shear will steadily increase as the storm heads north-northwest, and shear will reach a high 25 knots by Saturday morning as Karen closes in on the U.S. Gulf Coast, according to the latest SHIPS model forecast. The atmosphere will grow drier as Karen moves into the Northern Gulf of Mexico, and the drier air combined with increasing wind shear will retard development, making only slow intensification likely through Friday. 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 Karen more to the northeast as it approaches the coast on Friday evening and Saturday morning. The higher shear at that time should be able to induce weakening, and the 8 am EDT Thursday wind probability forecast from NHC gave a 28% chance Karen will be a hurricane at 2 am EDT Saturday, down from 44% on Friday afternoon. Most of the models predict landfall will occur along the western Florida Panhandle Saturday afternoon or evening. The usually reliable European model has Karen making landfall over Eastern Louisiana, though. If Karen does follow this more westerly path, the storm will be weaker, since there is more dry air and higher wind shear to the west. Since almost all of Karen's heavy thunderstorms will be displaced to the east by high wind shear, there will be relatively low rainfall totals of 1 - 3" to the immediate west of where the center makes landfall. Much higher rainfall totals of 4 - 8" can be expected to the east. To judge the possibilities of receiving tropical storm-force winds at your location, I recommend using the NHC wind probability forecast. The highest odds of tropical storm-force winds (45 - 55%) are along the coast from Buras, Louisiana, to Pensacola, Florida.

I'll have a new post this afternoon.

Jeff Masters

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Quoting 851. CybrTeddy:
Pressures down to 998mb.


Do you think it would be hurricane later today? Thanks!
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Quoting 872. HighTideNPcola:

10-4.  Speaking of the LLC, it seems to be moving a little faster than stated, but like you said, HH data will clear that up.


No prob.......Glad to see they are in air doing their job to protect us. God Bless Em.
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Anyone has conditions from western Cuba ?
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Member Since: July 3, 2005 Posts: 433 Comments: 132765
Quoting 847. guygee:
DO not click this link!
97L has become 97L
You will be sucked into the vortex of an infinite loop.


That's some meta stuff right there. :)
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Quoting 863. weathermanwannabe:


Not trying to confuse; I am looking at a hi-res close-up at the moment. Looks that way to my eyes....Could be wrong though, or a jog, or a slight trend.

The Hunters will answer my question at some point.
10-4.  Speaking of the LLC, it seems to be moving a little faster than stated, but like you said, HH data will clear that up.
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Starting to get deeper convection firing off right over the CoC.. we'll see if it expands.
Member Since: July 8, 2005 Posts: 259 Comments: 24937
Quoting 862. barbamz:

Wpac is donating a bit of moisture for Karen's dry western side?

Good observation!
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Race to the middle

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Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 3rd day of the month at 20:10Z
Date: October 3, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number: 12
Storm Name: Karen (flight in the North Atlantic basin)

Mission Number: 3
Observation Number: 25

20:10:30Z 23.333N 88.083W 960.2 mb
(~ 28.35 inHg) 391 meters
(~ 1,283 feet) 1004.1 mb
(~ 29.65 inHg) - From 164° at 52 knots
(From the SSE at ~ 59.8 mph) 22.5°C
(~ 72.5°F) 21.9°C
(~ 71.4°F) 55 knots
(~ 63.2 mph) 50 knots
(~ 57.5 mph) 3 mm/hr
(~ 0.12 in/hr) 47.3 knots (~ 54.4 mph)
Tropical Storm 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 20:01:00Z (first observation), the observation was 378 miles (609 km) to the W (261°) from Key West, FL, USA.

At 20:10:30Z (last observation), the observation was 407 miles (655 km) to the WSW (258°) from Key West, FL, USA.
Member Since: July 3, 2005 Posts: 433 Comments: 132765
Quoting 851. CybrTeddy:
Pressures down to 998mb.


jinkies....Karen is a very determined little lady
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Time: 20:06:30Z
Coordinates: 23.4833N 87.9167W
Acft. Static Air Press: 959.4 mb (~ 28.33 inHg)
Acft. Geopotential Hgt: 413 meters (~ 1,355 feet)
Extrap. Sfc. Press: 1006.3 mb (~ 29.72 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 120° at 65 knots (From the ESE at ~ 74.8 mph)
Air Temp: 19.6°C (~ 67.3°F)
Dew Pt: 19.5°C (~ 67.1°F)
Peak (10s) Flt. Lvl. Wind: 67 knots (~ 77.0 mph)
SFMR Peak (10s) Sfc. Wind: 52 knots (~ 59.8 mph)
SFMR Rain Rate: 6 mm/hr (~ 0.24 in/hr)
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Quoting CybrTeddy:
Pressures down to 998mb.

Pretty impressive.
If it wasn't for the dry air I would think it would be a hurricane today.
Shear not helping either.

Oh well. 2013, the Year of the Dry.
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Quoting 857. HighTideNPcola:

NOT true.  Just look at visible sat loop.  Steady N-NorthWest.  Clear as day.  Please don't confuse.


Not trying to confuse; I am looking at a hi-res close-up at the moment. Looks that way to my eyes....Could be wrong though, or a jog, or a slight trend.

The Hunters will answer my question at some point.
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Wpac is donating a bit of moisture for Karen's dry western side?
Member Since: October 25, 2008 Posts: 70 Comments: 7720
Member Since: January 1, 2008 Posts: 0 Comments: 3803
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Winds appear to be near 55kts.

200230 2338N 08745W 9591 00436 0086 +193 //// 118058 061 054 006 05
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Quoting 845. weathermanwannabe:
The coc has also been traveling about due North in the last 3 hours......I am thinking that the track might shift a little to the right in some of the model runs in the am if this trend continues.
NOT true.  Just look at visible sat loop.  Steady N-NorthWest.  Clear as day.  Please don't confuse.
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Haven't quite pegged the LLC yet, so pressures may be lower still.
Member Since: July 8, 2005 Posts: 259 Comments: 24937
Quoting 847. guygee:
DO not click this link!
97L has become 97L
You will be sucked into the vortex of an infinite loop.


Oh, come on, human nature means that I obviously want to click on the link (resist, resist) :)
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Oh hello...

Time: 20:03:00Z
Coordinates: 23.4167N 88.4167W
Acft. Static Air Press: 752.0 mb (~ 22.21 inHg)
Acft. Geopotential Hgt: 2,477 meters (~ 8,127 feet)
Extrap. Sfc. Press: 998.0 mb (~ 29.47 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 99° at 23 knots (From the E at ~ 26.4 mph)
Air Temp: 15.4°C (~ 59.7°F)
Dew Pt: 13.7°C (~ 56.7°F)
Peak (10s) Flt. Lvl. Wind: 23 knots (~ 26.4 mph)
SFMR Peak (10s) Sfc. Wind: 38 knots* (~ 43.7 mph*)
SFMR Rain Rate: 3 mm/hr* (~ 0.12 in/hr*)
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Quoting 847. guygee:
DO not click this link!
97L has become 97L
You will be sucked into the vortex of an infinite loop.

LOL. what the heck. xD
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Quoting 830. MiamiHurricanes09:
Karen gonna be one butt ugly hurricane if it ever makes it there.

Kinda like hurricane Gordon from 2000, just farther west.
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Pressures down to 998mb.
Member Since: July 8, 2005 Posts: 259 Comments: 24937
18z 27hr super cell composite

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12z Euro--









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Meanwhile the CMC shows a Central Atlantic system, normal for it but the GFS joins in





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DO not click this link!
97L has become 97L
You will be sucked into the vortex of an infinite loop.
Member Since: Posts: Comments:



Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 3rd day of the month at 20:00Z
Date: October 3, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number: 12
Storm Name: Karen (flight in the North Atlantic basin)

Mission Number: 3

Observation Number: 24

20:00:30Z 23.717N 87.667W 959.7 mb
(~ 28.34 inHg) 437 meters
(~ 1,434 feet) 1009.6 mb
(~ 29.81 inHg) - From 124° at 56 knots
(From between the ESE and SE at ~ 64.4 mph) 19.4°C
(~ 66.9°F) 19.4°C
(~ 66.9°F) 58 knots
(~ 66.7 mph) 49 knots
(~ 56.3 mph) 9 mm/hr
(~ 0.35 in/hr) 47.3 knots (~ 54.4 mph)
Tropical Storm 84.5%
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 19:51:00Z (first observation), the observation was 348 miles (560 km) to the W (264°) from Key West, FL, USA.

At 20:00:30Z (last observation), the observation was 376 miles (605 km) to the W (261°) from Key West, FL, USA.
Member Since: July 3, 2005 Posts: 433 Comments: 132765
The coc has also been traveling about due North in the last 3 hours......I am thinking that the track might shift a little to the right in some of the model runs in the am if this trend continues.
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Quoting 839. EllasD:


most will stay at a Casino, where they have parking garages, I know far less about the weather than most, but it does look like if Karen does make landfall, she will move away from us quickly and we will have a great week for the Cruisers. This is the last big hoo-raw for our tourist season and the Cruisers bring big money here, so you can count on all the cities cleaning up very quickly. As of now there is NO word of nixing Cruising the Coast


Good. Hope all have fun (and don't lose too much money).
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Karen looks to have done little strengthening today. It has, however, deepened a few millibars.
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Time: 20:00:00Z
Coordinates: 23.7333N 87.65W
Acft. Static Air Press: 959.2 mb (~ 28.33 inHg)
Acft. Geopotential Hgt: 445 meters (~ 1,460 feet)
Extrap. Sfc. Press: 1009.8 mb (~ 29.82 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 122° at 54 knots (From the ESE at ~ 62.1 mph)
Air Temp: 19.6°C (~ 67.3°F)
Dew Pt: 19.5°C (~ 67.1°F)
Peak (10s) Flt. Lvl. Wind: 56 knots (~ 64.4 mph)
SFMR Peak (10s) Sfc. Wind: 50 knots (~ 57.5 mph)
SFMR Rain Rate: 9 mm/hr (~ 0.35 in/hr)
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Member Since: July 3, 2005 Posts: 433 Comments: 132765
Quoting 826. daddyjames:


Oh sweet. Sorry that the weather won't be cooperating. May want to keep off the beach, as the wind blown sand may not be terribly agreeable with the paint job.


most will stay at a Casino, where they have parking garages, I know far less about the weather than most, but it does look like if Karen does make landfall, she will move away from us quickly and we will have a great week for the Cruisers. This is the last big hoo-raw for our tourist season and the Cruisers bring big money here, so you can count on all the cities cleaning up very quickly. As of now there is NO word of nixing Cruising the Coast
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Quoting 808. daddyjames:


Is that bike related or boat related? Either way, neither would be particularly enjoyable under the conditions forecast, I suppose.



It is car and bike related. Luckily, it is two weekends of action.
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18 z 21hr nam further west this run seems

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Member Since: January 1, 2008 Posts: 0 Comments: 3803
Winds up to 50kts as they penetrate the northeastern semicircle.

200000 2344N 08739W 9592 00445 0098 +196 +195 122054 056 050 009 00
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.
Member Since: June 30, 2013 Posts: 12 Comments: 9179
Kermit

Time: 19:53:00Z
Coordinates: 24.05N 88.35W
Acft. Static Air Press: 751.6 mb (~ 22.19 inHg)
Acft. Geopotential Hgt: 2,534 meters (~ 8,314 feet)
Extrap. Sfc. Press: 1007.2 mb (~ 29.74 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 104° at 27 knots (From the ESE at ~ 31.0 mph)
Air Temp: 12.4°C (~ 54.3°F)
Dew Pt: 12.0°C (~ 53.6°F)
Peak (10s) Flt. Lvl. Wind: 28 knots (~ 32.2 mph)
SFMR Peak (10s) Sfc. Wind: 40 knots (~ 46.0 mph)
SFMR Rain Rate: 3 mm/hr (~ 0.12 in/hr)
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Quoting 830. MiamiHurricanes09:
Karen gonna be one butt ugly hurricane if it ever makes it there.


Ingrid was a fairly ugly hurricane for most of its time as one too, so it fits with the theme. Probably a half-exposed LLC if it becomes one. I'm not holding my breath.
Member Since: July 8, 2005 Posts: 259 Comments: 24937
Quoting 825. KEEPEROFTHEGATE:
18z nam out too hr 15

Karen going to visit MoM?
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Karen gonna be one butt ugly hurricane if it ever makes it there.
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That's some interesting rotation in the Bermuda Triangle.
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Quoting VR46L:



STAND CLEAR!!!!

LOLOL
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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