Ex Tropical Depression KAREN: Discussions & Images

[Brent]

BULLETIN
TROPICAL DEPRESSION TWELVE ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007
1100 PM AST MON SEP 24 2007

...TROPICAL DEPRESSION TWELVE FORMS IN THE EASTERN ATLANTIC...

AT 1100 PM AST...0300Z...THE CENTER OF TROPICAL DEPRESSION TWELVE
WAS LOCATED NEAR LATITUDE 10.1 NORTH...LONGITUDE 36.2 WEST OR ABOUT
1700 MILES...2735 KM...EAST OF THE SOUTHERN WINDWARD ISLANDS.

THE DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 16 MPH AND
THIS GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE NEXT 24
HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS AND
THE DEPRESSION IS EXPECTED TO BECOME A TROPICAL STORM ON TUESDAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES.

REPEATING THE 1100 PM AST POSITION...10.1 N...36.2 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 16 MPH. MAXIMUM SUSTAINED WINDS...35
MPH. MINIMUM CENTRAL PRESSURE...1006 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM AST.

$$
FORECASTER BROWN

[Brent]

[Buck]

okay, now that we have a TD, let's place bets on when it will become Karen (or Lorenzo should another storm happen to leapfrog it).

I'm thinking 11am or 5pm tomorrow.

[fci]

Wilma was east of the Bahamas after it flattened Grand Bahama Island

Maps of the track that I have looked at show that the center never was east of Grand Bahama nor even crossed the island. The eye was huge but the center does not look like it got Grand Bahama and was never east of the Bahamas.

I have two maps; from Weather Underground and NOAA CSC:

[HurricaneRobert]

Yes, it was isabel. Dog 1950 was also one. But they are very rare. In out near 40-50 west the TCHP could not support one.

Floyd was so close to catefory 5. At it's present longitude this thing is bigger than Floyd.

[Sanibel]

Out to sea. Climatology wins.

[wxmann_91]

Not very enthusiastic about this system becoming strong. There's a strong zone of shear just to the north, so it may befall another fate similar to Ingrid. Also the large size means there's going to be a tendency for the convection to compete against each other and for dry air to get entrained in. Unless it can consolidate which it may be doing now.

[Chacor]

872
WTNT42 KNHC 250234
TCDAT2
TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007
1100 PM EDT MON SEP 24 2007

THE LARGE LOW PRESSURE AREA IN THE EASTERN ATLANTIC HAS ACQUIRED
ENOUGH ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A
2004 UTC QUIKSCAT OVERPASS WAS HELPFUL IN LOCATING THE CENTER OF
THE DEPRESSION AND THE QUIKSCAT DATA SUGGEST THAT THE MAXIMUM WINDS
WERE AROUND 25 KT AT THAT TIME. SINCE THEN...DEEP CONVECTION
HAS INCREASED NEAR THE CENTER AND DVORAK CLASSIFICATIONS FROM TAFB
AND SAB SUPPORT TROPICAL STORM STRENGTH. HOWEVER...THERE WAS SOME
SPREAD IN THE CENTER LOCATION OF THESE ESTIMATES...SO THE INITIAL
INTENSITY IS SET AT 30 KT.

THE INITIAL MOTION ESTIMATE IS 285/14. THE DEPRESSION IS EXPECTED TO
CONTINUE MOVING WEST-NORTHWESTWARD SOUTH OF A MID-LEVEL RIDGE OVER
THE CENTRAL AND EASTERN ATLANTIC DURING THE NEXT FEW DAYS. A
WEAKNESS IN THE RIDGE IS FORECAST TO DEVELOP OVER THE CENTRAL
ATLANTIC IN 4 OR 5 DAYS...WHICH SHOULD ALLOW FOR A NORTHWESTWARD
TURN LATER IN THE FORECAST PERIOD. THE DYNAMICAL MODEL GUIDANCE
GENERALLY AGREES ON THIS SCENARIO...BUT THERE IS SOME SPREAD IN
HOW FAR WEST THE CYCLONE WILL BE WHEN THE TURN MATERIALIZES. THE
GFS...AND GFDL ARE FARTHER WEST...WHILE THE NOGAPS AND ECMWF ARE
ALONG THE EASTERN SIDE OF THE GUIDANCE. THE OFFICIAL FORECAST IS
ALONG THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE AND LEANS CLOSER
TO THE GFS/GFDL SOLUTIONS.

THE INTENSITY FORECAST IS SOMEWHAT PROBLEMATIC. THE DEPRESSION
APPEARS TO BE IN A FAVORABLE ENVIRONMENT FOR STRENGTHENING DURING
THE NEXT COUPLE OF DAYS. THE SHIPS MODEL BRINGS THE DEPRESSION TO
HURRICANE STATUS IN 48 HOURS WHILE THE DYNAMICAL MODEL GUIDANCE IS
LESS AGGRESSIVE DURING THIS TIME FRAME. BEYOND 72 HOURS...THE
GLOBAL MODELS INDICATE THAT SOUTH TO SOUTHWESTERLY SHEAR WILL
INCREASE...WHICH SHOULD HALT ADDITIONAL STRENGTHENING. THE
OFFICIAL INTENSITY FORECAST IS MORE CONSERVATIVE THAN THE SHIPS
GUIDANCE AND IS CLOSER TO THE GFDL INTENSITY FORECAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL 25/0300Z 10.1N 36.2W 30 KT
12HR VT 25/1200Z 10.6N 38.4W 35 KT-
24HR VT 26/0000Z 11.2N 41.4W 45 KT
36HR VT 26/1200Z 11.8N 44.5W 50 KT
48HR VT 27/0000Z 12.5N 47.4W 55 KT
72HR VT 28/0000Z 15.3N 50.9W 60 KT
96HR VT 29/0000Z 19.0N 53.0W 60 KT
120HR VT 30/0000Z 22.0N 54.5W 60 KT

$$
FORECASTER BROWN

[Brent]

TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122007
1100 PM EDT MON SEP 24 2007

THE LARGE LOW PRESSURE AREA IN THE EASTERN ATLANTIC HAS ACQUIRED
ENOUGH ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A
2004 UTC QUIKSCAT OVERPASS WAS HELPFUL IN LOCATING THE CENTER OF
THE DEPRESSION AND THE QUIKSCAT DATA SUGGEST THAT THE MAXIMUM WINDS
WERE AROUND 25 KT AT THAT TIME. SINCE THEN...DEEP CONVECTION
HAS INCREASED NEAR THE CENTER AND DVORAK CLASSIFICATIONS FROM TAFB
AND SAB SUPPORT TROPICAL STORM STRENGTH. HOWEVER...THERE WAS SOME
SPREAD IN THE CENTER LOCATION OF THESE ESTIMATES...SO THE INITIAL
INTENSITY IS SET AT 30 KT.

THE INITIAL MOTION ESTIMATE IS 285/14. THE DEPRESSION IS EXPECTED TO
CONTINUE MOVING WEST-NORTHWESTWARD SOUTH OF A MID-LEVEL RIDGE OVER
THE CENTRAL AND EASTERN ATLANTIC DURING THE NEXT FEW DAYS. A
WEAKNESS IN THE RIDGE IS FORECAST TO DEVELOP OVER THE CENTRAL
ATLANTIC IN 4 OR 5 DAYS...WHICH SHOULD ALLOW FOR A NORTHWESTWARD
TURN LATER IN THE FORECAST PERIOD. THE DYNAMICAL MODEL GUIDANCE
GENERALLY AGREES ON THIS SCENARIO...BUT THERE IS SOME SPREAD IN
HOW FAR WEST THE CYCLONE WILL BE WHEN THE TURN MATERIALIZES. THE
GFS...AND GFDL ARE FARTHER WEST...WHILE THE NOGAPS AND ECMWF ARE
ALONG THE EASTERN SIDE OF THE GUIDANCE. THE OFFICIAL FORECAST IS
ALONG THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE AND LEANS CLOSER
TO THE GFS/GFDL SOLUTIONS.

THE INTENSITY FORECAST IS SOMEWHAT PROBLEMATIC. THE DEPRESSION
APPEARS TO BE IN A FAVORABLE ENVIRONMENT FOR STRENGTHENING DURING
THE NEXT COUPLE OF DAYS. THE SHIPS MODEL BRINGS THE DEPRESSION TO
HURRICANE STATUS IN 48 HOURS WHILE THE DYNAMICAL MODEL GUIDANCE IS
LESS AGGRESSIVE DURING THIS TIME FRAME. BEYOND 72 HOURS...THE
GLOBAL MODELS INDICATE THAT SOUTH TO SOUTHWESTERLY SHEAR WILL
INCREASE...WHICH SHOULD HALT ADDITIONAL STRENGTHENING. THE
OFFICIAL INTENSITY FORECAST IS MORE CONSERVATIVE THAN THE SHIPS
GUIDANCE AND IS CLOSER TO THE GFDL INTENSITY FORECAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL 25/0300Z 10.1N 36.2W 30 KT
12HR VT 25/1200Z 10.6N 38.4W 35 KT-
24HR VT 26/0000Z 11.2N 41.4W 45 KT
36HR VT 26/1200Z 11.8N 44.5W 50 KT
48HR VT 27/0000Z 12.5N 47.4W 55 KT
72HR VT 28/0000Z 15.3N 50.9W 60 KT
96HR VT 29/0000Z 19.0N 53.0W 60 KT
120HR VT 30/0000Z 22.0N 54.5W 60 KT

$$
FORECASTER BROWN

[JTD]

Not very enthusiastic about this system becoming strong. There's a strong zone of shear just to the north, so it may befall another fate similar to Ingrid. Also the large size means there's going to be a tendency for the convection to compete against each other and for dry air to get entrained in. Unless it can consolidate which it may be doing now.

Correct. Also NHC is predicting the maximum intensity to reach only 60 knots in the 5 day forecast. Seems like they don't expect a hurricane.

[Evil Jeremy]

First advisory now out, showing recurve

[Buck]

I'm thinking it will be Karen by 5am now.

[Evil Jeremy]

Any chance of 12 bending back west after it moves north?

[chadtm80]

[wxmann_91]

Any chance of 12 bending back west after it moves north?

Well, assuming future Karen survives its bout of shear (it most likely will but then again most were banking for Ingrid to survive), it will all depend on how permanent the weakness is. Right now I'm thinking a significant turn northward around Days 4-5, a turn back west, and then eventual recurve. The hemispheric pattern is evolving into a rather progressive but amplified pattern so I do not think a US hit is in the works.

[Buck]

Any chance of 12 bending back west after it moves north?

If the ridge rebuilds before it gets too far north, I suppose it could. But anything more than a momentary meandering would be unlikely.

[Fego]

It will be such a strong weakness so it can pull north...

[CrazyC83]

Not very enthusiastic about this system becoming strong. There's a strong zone of shear just to the north, so it may befall another fate similar to Ingrid. Also the large size means there's going to be a tendency for the convection to compete against each other and for dry air to get entrained in. Unless it can consolidate which it may be doing now.

Correct. Also NHC is predicting the maximum intensity to reach only 60 knots in the 5 day forecast. Seems like they don't expect a hurricane.

Although they mention it is conservative as SHIPS is predicting a hurricane. I think we will see Hurricane Karen and a good chance of Major Hurricane Karen.

['CaneFreak]

bye bye thread title...it was nice while it lasted...

[cycloneye]

The Latest at 2:15 UTC