Monday, September 03, 2007

Tropical Storm Henriette Discussion #17

000
WTPZ41 KNHC 032054
TCDEP1
TROPICAL STORM HENRIETTE DISCUSSION NUMBER 17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP112007
200 PM PDT MON SEP 03 2007

WHILE HENRIETTE'S SATELLITE APPEARANCE HAS IMPROVED DURING THE DAY...AN AIR FORCE HURRICANE HUNTER AIRCRAFT WAS UNABLE TO FIND HURRICANE FORCE WINDS. THE INITIAL INTENSITY REMAINS 60 KT BASED ON A PEAK SFMR WIND OF 58 KT. THE CYCLONE HAS ANOTHER 24-36 HOURS OVER OPEN WATERS AND THE OFFICIAL FORECAST CALLS FOR HENRIETTE TO BECOME A HURRICANE PRIOR TO REACHING BAJA CALIFORNIA. INTENSITY GUIDANCE HAS BEEN TRENDING WEAKER AND THE OFFICIAL FORECAST IS NUDGED LOWER.

HENRIETTE CONTINUES TO CRAWL ALONG WITH AN INITIAL MOTION ESTIMATE OF 315/05. THE OVERALL FORECAST PHILOSOPHY REMAINS UNCHANGED. THE CYCLONE IS EXPECTED TO GRADUALLY TURN NORTHWARD OVER THE NEXT 2 DAYS IN RESPONSE TO A MID-LATITUDE TROUGH CURRENTLY APPROACHING THE WEST COAST OF THE UNITED STATES. DYNAMICAL MODELS REMAIN REASONABLY CLUSTERED ABOUT A TRACK THAT TAKES THE CYCLONE TOWARD THE SOUTHWESTERN COAST OF BAJA CALIFORNIA IN 36-48 HOURS. DESPITE THE CLUSTERING...DYNAMICAL MODELS HAVE CONSISTENTLY BEEN TOO FAST IN THEIR FORWARD SPEED. BASED ON THIS TENDENCY...THE OFFICIAL FORECAST IS A LITTLE SLOWER THAN THE MODEL CONSENSUS DURING THE FIRST 36 HOURS. ONCE IT CROSSES THE BAJA PENINSULA...HENRIETTE IS EXPECTED TO CONTINUE NORTHWARD OVER THE GULF OF CALIFORNIA...WITH A SECOND LANDFALL OVER THE NORTHWESTERN COAST OF MAINLAND MEXICO IN 48-72 HOURS. DISSIPATION OVER NORTHWESTERN MEXICO IS EXPECTED SHORTLY AFTER LANDFALL. WHILE IT IS DOUBTFUL THAT THE CYCLONE WOULD SURVIVE A TRACK OVER THE HIGH TERRAIN OF NORTHWESTERN MEXICO...SOME OF THE RESIDUAL MOISTURE COULD MOVE INTO THE SOUTHWESTERN UNITED STATES.

FORECAST POSITIONS AND MAX WINDS

INITIAL 03/2100Z 20.1N 108.5W 60 KT
12HR VT 04/0600Z 20.9N 109.2W 65 KT
24HR VT 04/1800Z 22.3N 110.2W 70 KT
36HR VT 05/0600Z 23.8N 110.9W 70 KT
48HR VT 05/1800Z 25.4N 111.2W 55 KT...INLAND
72HR VT 06/1800Z 29.5N 111.0W 30 KT...INLAND
96HR VT 07/1800Z...DISSIPATED


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