[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 280249
TCDAT2
HURRICANE KATRINA DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SAT AUG 27 2005

REPORTS FROM AN AIR FORCE PLANE INDICATE THAT THE INTENSITY REMAINS
ABOUT 100 KNOTS...BUT THE WIND FIELD IS EXPANDING. THE MINIMUM
CENTRAL PRESSURE REPORTED THIS EVENING HAS BEEN 939 MB. THE
SATELLITE PRESENTATION HAS BEEN UP AND DOWN...AND HAS BEEN CHANGING
FROM A COIL TO A RING OF VERY DEEP CONVECTION THROUGHOUT THE
EVENING. T-NUMBERS CONTINUE AROUND 5.5 ON THE DVORAK SCALE WHICH
ALSO SUPPORTS 100 KNOTS. DATA FROM THE NOAA JET CURRENTLY SAMPLING
THE ENVIRONMENT...INDICATE THAT THE CYCLONIC CIRCULATION EXTENDS
UPWARD TO ABOUT 200 MB AND IT IS SURROUNDED BY A LARGE SCALE
UPPER-LEVEL ANTICYLONE. THIS PATTERN...IN COMBINATION WITH THE HIGH
OCEANIC HEAT CONTENT...FANCY WORDS FOR A WARM OCEAN...ALONG THE PATH
OF KATRINA...CALLS FOR ADDITIONAL STRENGTHENING. THE STRENGTHENING
IS ALSO FORECAST BY THE SHIPS AND THE GFDL MODELS WHICH BRING
KATRINA TO 130 AND 123 KNOTS...RESPECTIVELY. CHANGES IN THE INNER
CORE STRUCTURE BEFORE LANDFALL MAY MODIFY THE INTENSITY OF KATRINA
UP OR DOWN...BUT UNFORTUNATELY...THESE CHANGES ARE NOT POSSIBLE TO
FORECAST NOWADAYS WITH OUR PRESENT KNOWLEDGE. WE CAN ONLY DESCRIBE
THEM AS THEY OCCUR. HOWEVER...DESPITE THESE CHANGES IN THE INNER
CORE...THE BOTTOM LINE IS THAT KATRINA IS EXPECTED TO BE AN INTENSE
AND DANGEROUS HURRICANE HEADING TOWARD THE NORTH CENTRAL GULF
COAST...AND THIS HAS TO BE TAKEN VERY SERIOUSLY.

IT APPEARS THAT KATRINA HAS BEGUN TO MOVE TOWARD THE WEST-NORTHWEST
OR 290 DEGREES AT 6 KNOTS AS THE HIGH TO THE NORTHWEST OF THE
HURRICANE BEGINS TO RETREAT WESTWARD AND LEAVES A WEAKNESS OVER THE
CENTRAL GULF OF MEXICO. THE COMBINATION OF BUILDING HIGH PRESSURE
OVER THE WESTERN NORTH ATLANTIC...AND A WEAK TROUGH APPROACHING THE
GULF OF MEXICO FROM THE NORTHWEST...SHOULD RESULT IN A PATTERN THAT
FORCES KATRINA TO TURN NORTHWESTWARD AND NORTHWARD TOWARD THE
CENTRAL GULF COAST. THIS IS ALSO THE SOLUTION PROVIDED BY THE
GLOBAL MODEL CONSENSUS WHICH THE OFFICIAL FORECAST FOLLOWS VERY
CLOSELY.

FORECASTER AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL      28/0300Z 25.0N  86.2W   100 KT
 12HR VT     28/1200Z 25.4N  87.3W   110 KT
 24HR VT     29/0000Z 27.0N  89.0W   120 KT
 36HR VT     29/1200Z 29.0N  89.8W   125 KT
 48HR VT     30/0000Z 31.0N  89.8W    85 KT...INLAND
 72HR VT     31/0000Z 36.5N  87.0W    40 KT...INLAND
 96HR VT     01/0000Z 41.0N  80.5W    30 KT...BECOMING EXTRATROPICAL
120HR VT     02/0000Z 45.5N  71.4W    25 KT...EXTRATROPICAL


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