000
WTNT42 KNHC 210256
TCDAT2
HURRICANE KARL DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON SEP 20 2004
 
KARL HAS BEEN STRENGTHENING OVER THE PAST SIX HOURS AND DVORAK
T-NUMBERS ARE ONCE AGAIN UP TO 6.5 FROM BOTH TAFB AND SAB WHILE
REMAINING STEADY AT 5.5 FROM AFWA. CLOUD TOP TEMPERATURES TEND TO
SHOW UP A LITTLE COOLER FOR MET-8 AS COMPARED TO GOES-12...WHICH
PROBABLY EXPLAINS WHY TAFB AND SAB ARE A LITTLE HIGHER THAN AFWA.
REGARDLESS...BOTH SATELLITES REPRESENTATIONS SHOW A WIDE BAND OF
COOLING CLOUD TOPS SURROUNDING THE EYE. IN ADDITION...A 2207Z TRMM
PASS REVEALED THAT THE STRENGTHENING EYEWALL IS BECOMING MORE
ENCLOSED WITH ONLY A SMALL OPENING ON THE SOUTH SIDE. SINCE CI
NUMBERS HAVE BEEN HOLDING STEADY BETWEEN 6.0 AND 6.5 FOR THE PAST
24 HOURS AND THE CONVECTIVE PATTERN IS IMPROVING...THE INITIAL
INTENSITY IS SET AT 120 KT.

THE INITIAL MOTION IS A LITTLE MORE TO THE RIGHT AT 315/9. THE MODEL
GUIDANCE WANTS TO RUN KARL OUT OF THE GATES AT A FASTER PACE FOR
THE FIRST 24 HOURS...MORE LIKE 12 KNOTS...BUT THE OFFICIAL FORECAST
HOLDS IT BACK A BIT IN LINE WITH CURRENT TRENDS. HOWEVER...
ACCELERATION IS ANTICIPATED OVER THE NEXT 24 HOURS AS THE SYSTEM
MOVES AROUND THE MID-LEVEL RIDGE TO ITS EAST AND HEADS TOWARDS A
DEEP TROUGH NEAR THE CANADIAN MARITIMES. 

KARL SHOULD CONTINUE TO STRENGTHEN OVER THE NEXT 6 HOURS AND RETAIN
A MAXIMUM INTENSITY THROUGH 24 HOURS AS IT BEGINS TO ROUND THE
POINT OF RECURVATURE. THE HURRICANE WILL THEN GRADUALLY WEAKEN
BETWEEN 24 AND 48 HOURS...AND THEN MORE QUICKLY THEREAFTER AS SHEAR
INCREASES AND SSTS COOL BELOW 26C AFTER 48 HOURS. EXTRATROPICAL
TRANSITION IS EXPECTED BY 96 HOURS WITH KARL BECOMING INCORPORATED
INTO THE DEEP POLAR VORTEX JUST EAST OF THE CANADIAN MARITIMES.

FORECASTER BERG/JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0300Z 19.1N  47.4W   120 KT
 12HR VT     21/1200Z 20.1N  48.5W   125 KT
 24HR VT     22/0000Z 22.3N  49.8W   125 KT
 36HR VT     22/1200Z 25.4N  50.1W   120 KT
 48HR VT     23/0000Z 28.5N  49.0W   115 KT
 72HR VT     24/0000Z 36.0N  45.0W   100 KT
 96HR VT     25/0000Z 44.0N  44.5W    80 KT...EXTRATROPICAL
120HR VT     26/0000Z 49.0N  47.0W    60 KT...EXTRATROPICAL
 
 
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