[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 220830
TCDAT2
HURRICANE KARL DISCUSSION NUMBER  23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT WED SEP 22 2004

A DOUBLE-EYEWALL STRUCTURE IS EVIDENT IN RECENT SATELLITE PICTURES
AND MICROWAVE PASSES OF KARL.  AN INNER EYEWALL LESS THAN 15 NM IN
DIAMETER IS PRESENT ALONG WITH A MUCH LARGER OUTER EYEWALL OF ABOUT
75 NM. CONVECTION HAS BECOME MORE INTENSE AROUND BOTH EYEWALLS...
ESPECIALLY IN THE NORTHERN SEMICIRCLE.  HOWEVER SATELLITE INTENSITY
ESTIMATES ARE A BIT LOWER THAN 6 HOURS AGO AS THE CI NUMBERS HAVE
FALLEN AND THE CURRENT WINDS ARE DECREASED TO 100 KT.

KARL REMAINS ON TRACK... MOVING NORTHWARD AT ABOUT 15 KT.  THE
CYCLONE IS LIKELY NEAR ITS RECURVATURE POINT AHEAD OF A LARGE
DEEP-LAYERED TROUGH TO ITS NORTHWEST.  MODEL GUIDANCE HAS CHANGED
LITTLE AND REMAINS CLUSTERED AROUND AN ACCELERATING NORTH TO
NORTH-NORTHEAST TRAJECTORY THROUGH DAY 3.  EXTRATROPICAL TRANSITION
SHOULD BEGIN SHORTLY AFTER 48 HOURS OVER COOLER WATER AND
INCREASING VERTICAL WIND SHEAR.  GLOBAL MODELS SUGGEST KARL WILL
EVENTUALLY BECOME A LARGE MID-LATITUDE CYCLONE AND WIND RADII
REFLECT THE GFS WIND FORECASTS.

THERE DOESN'T APPEAR TO BE MUCH SHEAR OVER THE HURRICANE AND LITTLE
CHANGE IN STRENGTH IS FORECAST FOR NEXT 24 HOURS.  AFTERWARD A
COMBINATION OF INCREASING SHEAR AND COOLER WATER TEMPERATURE SHOULD
TAKE ITS TOLL ON KARL ESPECIALLY AT 48 HOURS AND BEYOND...WITH
GREATER THAN 30 KT OF SHEAR FORECAST.  THE FORECAST INTENSITY IS IN
LINE WITH THE SHIPS GUIDANCE UNTIL THE SYSTEM BECOMES EXTRATROPICAL.
AFTERWARDS...THE GFS MODEL WAS THE MAIN BASIS FOR THE 3 AND 4 DAY
FORECAST.

FORECASTER BLAKE/PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      22/0900Z 25.7N  49.5W   100 KT
 12HR VT     22/1800Z 27.7N  49.1W   100 KT
 24HR VT     23/0600Z 30.4N  47.4W    95 KT
 36HR VT     23/1800Z 34.0N  45.0W    90 KT
 48HR VT     24/0600Z 38.5N  43.0W    75 KT
 72HR VT     25/0600Z 48.0N  39.5W    65 KT...EXTRATROPICAL
 96HR VT     26/0600Z 55.5N  32.0W    55 KT...EXTRATROPICAL
120HR VT     27/0600Z...ABSORBED


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