ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM TROPICAL STORM HENRI DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102009 500 PM AST WED OCT 07 2009 HENRI IS WEAKENING THIS AFTERNOON WITH THE LOW-LEVEL CENTER MOVING EVEN FARTHER AWAY FROM A PERSISTENT AREA OF STRONG CONVECTION. THE LOW-LEVEL CIRCULATION ALSO IS BECOMING LESS WELL-DEFINED WITH A SECONDARY CENTER NOTED ON RECENT VISIBLE IMAGES. A BLEND OF THE TAFB/SAB DVORAK ESTIMATES GIVEN AN INITIAL WIND SPEED OF 35 KT... BUT THIS COULD BE A LITTLE GENEROUS. STRONG WEST TO SOUTHWEST SHEAR IS LIKELY FOR A DAY OR SO...WHICH WILL CONTINUE TO WEAKEN THE CYCLONE. IF HENRI SURVIVES THAT SHEAR...AN UPPER-TROUGH AXIS WITH CONFLUENT FLOW ALOFT SHOULD PROVIDE THE KNOCKOUT BLOW TO THE TROPICAL CYCLONE. THE OFFICIAL FORECAST IS BASICALLY AN UPDATE TO THE PREVIOUS ONE...SHOWING DISSIPATION WITHIN 24 HOURS. HOWEVER... IF DEEP CONVECTION DOES NOT RETURN NEAR THE CENTER...THIS SYSTEM COULD BECOME A REMNANT LOW SOONER THAN INDICATED BELOW. USING A MEAN MOTION OF THE TWO CENTERS...THE INITIAL MOTION IS 290/12. A WEST-NORTHWEST PATH IS PROBABLE FOR THE NEXT DAY OR SO BEFORE RIDGING BUILDS OVER THE WESTERN ATLANTIC. THIS RIDGE SHOULD CAUSE HENRI...OR THE REMNANTS THEREOF...TO TURN WESTWARD OR EVEN SOUTH OF WEST UNTIL THE LOW DISSIPATES. THIS SOLUTION HAS GOOD SUPPORT FROM MODEL GUIDANCE...AND THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ONE...REMAINING ON THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE NEAR BAM SHALLOW. FORECAST POSITIONS AND MAX WINDS INITIAL 07/2100Z 19.4N 58.6W 35 KT 12HR VT 08/0600Z 20.1N 60.3W 30 KT 24HR VT 08/1800Z 20.9N 62.0W 25 KT...REMNANT LOW 36HR VT 09/0600Z 21.2N 63.6W 20 KT...REMNANT LOW 48HR VT 09/1800Z 21.0N 66.0W 20 KT...REMNANT LOW 72HR VT 10/1800Z...DISSIPATED $$ FORECASTER BLAKE NNNN
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Page last modified: Thursday, 31-Dec-2009 12:09:11 UTC