Caribbean-On-Line's Caribbean Hurricane Blog



TROPICAL STORM HANNA DISCUSSION NUMBER 32

Published on September 4, 2008 5:25 PM | Comments

TROPICAL STORM HANNA DISCUSSION NUMBER 32 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008 500 PM EDT THU SEP 04 2008

THE RECONNAISSANCE AIRCRAFT INVESTIGATING HANNA IS FINDING THE CIRCULATION CENTER AT 850 MB DISPLACED TO THE NORTHWEST OF THE MEAN CENTER OF ROTATION APPARENT IN THE LOW CLOUD LINES. THERE ARE ALSO MULTIPLE SWIRLS...BUT IT DOES APPEAR THAT THE LOW-LEVEL CENTER HAS JUMPED A LITTLE BIT TO THE WEST IN RESPONSE TO THE CONVECTIVE ASYMMETRY. ALTHOUGH A COUPLE MORE SHIFTS ARE POSSIBLE...THE ORIENTATION OF THE SHEAR SHOULD TURN MORE SOUTHERLY WITH TIME...THAT IS...MORE ALONG THE TRACK...AND THEN HAVE LESS OF AN IMPACT ON THE TRACK. THE BASIC FORECAST PHILOSOPHY IS UNCHANGED. THE NEW TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS ONE WITH ONLY A SLIGHT LEFTWARD SHIFT...AND IS NEAR THE MODEL CONSENSUS.

RECONNAISSANCE DATA THUS FAR DO NOT SUPPORT ANY INCREASE IN THE INTENSITY ESTIMATE. WATER VAPOR IMAGERY CONTINUES TO SHOW VERY DRY AIR IMPINGING ON HANNA FROM THE SOUTHEAST...AND THIS IS EXPECTED TO CONTINUE. WHILE THE VERTICAL SHEAR IS FORECAST TO DIMINISH A LITTLE PRIOR TO LANDFALL...NONE OF THE OBJECTIVE GUIDANCE MODELS NOW MAKE HANNA A HURRICANE AND THE OFFICIAL INTENSITY FORECAST NOW TOPS OUT AT 60 KT. HURRICANE WATCHES WILL REMAIN IN EFFECT FOR THE POSSIBILITY THAT HANNA BECOMES A LITTLE STRONGER THAN FORECAST...AND PEOPLE ARE REMINDED THAT THERE IS VERY LITTLE DIFFERENCE BETWEEN A STRONG TROPICAL STORM AND A MINIMAL HURRICANE.



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