[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 290909
TCDAT2
HURRICANE KATRINA DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON AUG 29 2005

AIR FORCE RECON HAS BEEN INVESTIGATING KATRINA THIS MORNING AND HAS
REPORTED SOME MECHANICAL PROBLEMS WHICH HAS PREVENTED MAKING A
COMPLETE ASSESSMENT OF THE INTENSITY IN THE NORTHEAST QUADRANT.
HOWEVER...FLIGHT-LEVEL WINDS OF 132-134 KT HAVE BEEN REPORTED IN
THE SOUTHEAST QUADRANT...WHILE NOAA DOPPLER RADAR VELOCITIES FROM
WFO SLIDELL EXCEEDING 123 KT HAVE BEEN OBSERVED IN THE NORTHEAST
QUADRANT BETWEEN 12000-16000 FT. THESE WIND VALUES WOULD SUPPORT AT
LEAST 125 KT SURFACE WINDS. ALTHOUGH THE CENTRAL PRESSURE HAS
CONTINUED TO INCREASE AND IS NOW 915 MB...THIS WOULD USUALLY
SUPPORT ABOUT 145 KT SURFACE. THE INITIAL INTENSITY OF 130 KT IS A
BLEND OF THESE VALUES.

THE INITIAL MOTION IS 360/13. KATRINA IS MOVING NORTHWARD AROUND THE
WESTERN PERIPHERY OF A LARGE-SCALE MID- TO UPPER-LEVEL RIDGE
LOCATED OVER THE FLORIDA PENINSULA AND EXTENDING NORTHWESTWARD
ACROSS THE SOUTHEASTERN UNITED STATES. THE COMBINATION OF THE
STRONG RIDGE AND AN APPROACHING MID-LEVEL TROUGH FROM THE WEST
SHOULD ACT TO KEEP KATRINA MOVING GENERALLY NORTHWARD FOR THE NEXT
12 HOURS OR SO. BY 24 HOURS...THE HURRICANE IS EXPECTED TO TURN
NORTHEASTWARD AS A STRONGER TROUGH LIFTS OUT THE SYSTEM AND
TRANSITIONS IT INTO AN EXTRATROPICAL LOW OVER THE GREAT LAKES
REGION. THE OFFICIAL FORECAST TRACK IS JUST A LITTLE TO THE LEFT OF
THE PREVIOUS TRACK AND IS SIMILAR TO THE NHC MODEL CONSENSUS.

SOME FLUCTUATIONS IN INTENSITY ARE POSSIBLE RIGHT UP UNTIL LANDFALL
OCCURS. HOWEVER...IT APPEARS THAT KATRINA WILL MAKE LANDFALL AS A
CATEGORY 4 HURRICANE LATER THIS MORNING. THE CLOUD PATTERN IN
SATELLITE IMAGERY HAS ERODED ON THE WEST SIDE DUE TO DRY AIR
ENTRAINMENT...AND THE EYEWALL HAS OPENED UP TO THE SOUTH AND
SOUTHWEST IN RADAR IMAGERY. HOWEVER...THE WATER REMAINS QUITE WARM
UNDERNEATH THE CENTER...AND CONVECTION CAN EASILY REDEVELOP AND THE
EYEWALL CLOSE OFF AGAIN BEFORE LANDFALL OCCURS. SOME DISRUPTION OF
THE CIRCULATION WILL OCCUR ONCE THE CENTER MOVES OVER SOUTHEASTERN
LOUISIANA. HOWEVER...THE FORECAST TRACK KEEPS THE EYE CLOSE ENOUGH
TO WARM WATER NEAR THE LOUISIANA AND MISSISSIPPI COASTS. THE
UPPER-LEVEL OUTFLOW PATTERN REMAINS QUITE IMPRESSIVE AND EVEN
CONTAINS A RARE 200 MB INDRAFT ANTICYCLONE TO THE EAST NEAR TAMPA
BAY. THE COMBINATION OF THE OUTFLOW REGIME AND THE CLOSE PROXIMITY
TO WARM WATER MAY BE ENOUGH TO KEEP KATRINA A MAJOR HURRICANE WHEN
IT REACHES THE LOUISIANA-MISSISSIPPI BORDER AREA THIS AFTERNOON.
JUST BECAUSE KATRINA IS NO LONGER A CATGEORY 5 HURRICANE DOES NOT
MEAN THAT EXTENSIVE DAMAGE AND STORM SURGE FLOODING WILL NOT OCCUR.
THIS IS STILL AN EXTREMELY DANGEROUS AND POTENTIALLY DEADLY
HURRICANE!

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      29/0900Z 28.8N  89.6W   130 KT
 12HR VT     29/1800Z 30.6N  89.6W   110 KT...INLAND
 24HR VT     30/0600Z 33.6N  89.0W    60 KT...INLAND
 36HR VT     30/1800Z 36.7N  87.2W    35 KT...INLAND
 48HR VT     31/0600Z 39.8N  84.1W    30 KT...INLAND
 72HR VT     01/0600Z 45.5N  76.5W    25 KT...INLAND EXTRATROPICAL
 96HR VT     02/0600Z 51.0N  68.0W    25 KT...INLAND EXTRATROPICAL
120HR VT     03/0600Z...DISSIPATED INLAND

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