155
WTNT44 KNHC 051445
TCDAT4
TROPICAL STORM GRACE DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092009
1100 AM AST MON OCT 05 2009
THE CONVECTIVE STRUCTURE OF GRACE HAS BEGUN TO DETERIORATE
SLIGHTLY...WITH THE RING OF DEEP CONVECTION AROUND THE CENTER
BECOMING LESS SYMMETRIC AND FRACTURED. THE INITIAL INTENSITY IS
LOWERED TO 55 KT ON THIS ADVISORY BASED ON TROPICAL AND SUBTROPICAL
CLASSIFICATIONS OF 3.5...AND A 0644 UTC QUIKSCAT PASS WHICH
SUPPORTED MAXIMUM WINDS BETWEEN 50 AND 55 KT. ALSO...GRACE IS NOW
OVER WATER NEAR 18C...AND THIS IS LIKELY INHIBITING STRONG
CONVECTIVE MIXING OF WINDS TO THE SURFACE. SOME ADDITIONAL
WEAKENING IS ANTICIPATED OVER THE NEXT 24 HOURS...AND THE GLOBAL
MODELS ALL INDICATE THAT GRACE SHOULD BE ABSORBED BY A FRONT JUST
SOUTHWEST OF IRELAND BY TUESDAY MORNING.
GRACE IS ACCELERATING WITH AN INITIAL MOTION OF 30 DEGREES AT 27 KT.
THE CYCLONE IS EXPECTED TO TURN TOWARD THE NORTH-NORTHEAST AND SLOW
DOWN OVER THE NEXT 12 TO 24 HOURS AS IT MOVES NORTH OF THE STRONGEST
BELT OF MID-LATITUDE WESTERLIES...AND BECOMES ABSORBED BY THE
FRONTAL BOUNDARY TO ITS NORTHWEST.
DESPITE THE FACT THAT GRACE IS MOVING OVER VERY COLD WATERS...AN
AMSU PASS FROM EARLIER TODAY STILL SHOWS THE PRESENCE OF A MODERATE
TO DEEP WARM CORE IN ASSOCIATION WITH THE CYCLONE. IN ADDITION...
THE WIND RADII HAVE BEEN ADJUSTED BASED ON THE 0644 UTC QUIKSCAT
PASS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 05/1500Z 45.4N 16.4W 55 KT
12HR VT 06/0000Z 48.0N 14.6W 50 KT
24HR VT 06/1200Z...ABSORBED BY A FRONT
FORECASTER BERG
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