[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 282047
TCDAT2
HURRICANE KATRINA DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SUN AUG 28 2005

KATRINA IS MAINTAINING A CLASSIC PRESENTATION ON SATELLITE
IMAGES...AND CATEGORY 5 INTENSITY.  THE CENTRAL PRESSURE MEASURED
BY A NOAA HURRICANE HUNTER PLANE AT 1755Z AND 1923Z WAS 902
MB...WHICH IS THE FOURTH LOWEST ON RECORD IN THE ATLANTIC BASIN
BEHIND HURRICANE GILBERT OF 1988...THE LABOR DAY HURRICANE OF
1935...AND HURRICANE ALLEN OF 1980.  HAVING SAID THAT...DATA FROM
THE STEPPED-FREQUENCY MICROWAVE RADIOMETER INSTRUMENT ON BOARD THE
AIRCRAFT SUGGEST THAT THE SURFACE TO 700 MB FLIGHT LEVEL WIND RATIO
IS NOT QUITE AS LARGE AS WE TYPICALLY USE...AND THE INITIAL
INTENSITY IS ADJUSTED SLIGHTLY TO 145 KT.  HURRICANES DO NOT
MAINTAIN SUCH GREAT INTENSITY FOR VERY LONG.  HOWEVER THERE ARE NO
OBVIOUS LARGE-SCALE MECHANISMS...SUCH AS INCREASED VERTICAL
SHEAR...TO WEAKEN KATRINA.  THE HURRICANE IS LIKELY TO MAKE
LANDFALL WITH CATEGORY 4 OR 5 INTENSITY.

THERE IS NOT MUCH CHANGE TO THE TRACK FORECAST PHILOSOPHY.  INITIAL
MOTION IS ABOUT 315/11.  KATRINA IS EXPECTED TO GRADUALLY TURN
NORTHWARD INTO A BREAK IN THE SUBTROPICAL RIDGE ASSOCIATED WITH A
LARGE MID-LATITUDE CYCLONE NEAR THE GREAT LAKES.  THE 12Z GFDL
HURRICANE MODEL'S TRACK HAS SHIFTED A LITTLE WESTWARD...AS HAS THE
LATEST NOGAPS RUN.  THE OFFICIAL FORECAST IS SLIGHTLY TO THE WEST
AND SLIGHTLY FASTER THAN THE PREVIOUS NHC TRACK.  THIS IS VERY
CLOSE TO BOTH THE DYNAMICAL MODEL CONSENSUS... AND TO THE LATEST
FSU SUPERENSEMBLE TRACK.  AMONG OUR MOST RELIABLE MODELS...ONLY THE
U.K. MET. OFFICE IS SIGNIFICANTLY TO THE EAST OF THE OFFICIAL
FORECAST TRACK.  IT SHOULD BE NOTED THAT THE SMALL CHANGE IN THE
OFFICIAL FORECAST TRACK IS ESSENTIALLY AT THE NOISE LEVEL.  ONE
SHOULD NOT FOCUS ON THE EXACT TRACK...PARTICULARLY IN THE CASE OF A
HURRICANE AS LARGE AS THIS ONE.  DESTRUCTIVE EFFECTS WILL LIKELY BE
FELT WELL AWAY FROM THE CENTER AND IT IS NOT POSSIBLE TO SPECIFY
WHICH COUNTIES OR PARISHES WILL EXPERIENCE THE WORST CONDITIONS.

ON THE BASIS OF AIRCRAFT FLIGHT LEVEL AND SFMR SURFACE WIND
DATA...THE WIND RADII HAVE BEEN EXPANDED EVEN MORE OVER THE
NORTHERN SEMICIRCLE.  HURRICANE FORCE WINDS ARE FORECAST TO SPREAD
AT LEAST 150 N MI INLAND ALONG THE PATH OF KATRINA.  CONSULT INLAND
HURRICANE AND TROPICAL STORM WARNINGS ISSUED BY NATIONAL WEATHER
SERVICE FORECAST OFFICES.

FORECASTER PASCH


FORECAST POSITIONS AND MAX WINDS

INITIAL      28/2100Z 26.9N  89.0W   145 KT
 12HR VT     29/0600Z 28.3N  89.8W   145 KT
 24HR VT     29/1800Z 30.6N  89.9W   130 KT...INLAND
 36HR VT     30/0600Z 33.4N  89.2W    60 KT...INLAND
 48HR VT     30/1800Z 36.0N  87.5W    35 KT...INLAND
 72HR VT     31/1800Z 41.0N  81.5W    30 KT...INLAND
 96HR VT     01/1800Z 48.0N  72.5W    25 KT...EXTRATROPICAL
120HR VT     02/1800Z...ABSORBED

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