WTNT43 KNHC 130302 TCDAT3 HURRICANE CHARLEY DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT THU AUG 12 2004
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE THAT WHILE THE CENTRAL PRESSURE HAS FALLEN TO 975 MB...WINDS FROM DROPSONDES AND AT THE AIRCRAFT FLIGHT LEVEL ARE SO FAR NO HIGHER THAN ON THE PREVIOUS FLIGHT. THE AIRCRAFT AND LAND BASED RADAR FROM KEY WEST FLORIDA AND CIENFUEGOS CUBA HAVE SHOWN THE 15-20 NM DIAMETER EYEWALL SPORADICALLY BREAKING OPEN. IN CONTRAST... INFRARED SATELLITE IMAGERY SHOWS THE EYE BECOMING BETTER DEFINED... ALTHOUGH CHARLEY HAS THUS FAR NOT BEEN ABLE TO MAINTAIN STRONG SYMMETRIC CONVECTION AROUND IT. ALL THESE SIGNS POINT TO A SYSTEM THAT IS SLOWLY STRENGTHENING AT THIS TIME. BASED ON THE AIRCRAFT DATA AND SATELLITE INTENSITY ESTIMATES...THE INITIAL INTENSITY REMAINS 90 KT.
THE INITIAL MOTION IS NOW 340/12...A LITTLE SLOWER THAN EARLIER. RADAR TRACKING SHOWED A DUE NORTHWARD MOTION FOR A TIME THIS EVENING...WHICH RAISES THE QUESTION OF WHETHER CHARLEY IS TURNING NORTHWARD A LITTLE PERMATURELY. ASIDE FROM THAT...THE TRACK FORECAST IS FAIRLY STRAIGHT FORWARD. CHARLEY IS ON THE WEST SIDE OF THE SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC WHICH HAS ITS AXIS AT ABOUT 25N. A DEEP LAYER TROUGH COVERS THE CENTRAL AND EASTERN UNITED STATES. CHARLEY SHOULD MOVE GENERALLY NORTHWARD FOR 12-24 HR...THEN ACCELERATE NORTH-NORTHEASTWARD AHEAD OF THE TROUGH. ALL MODEL GUIDANCE AGREES WITH THIS BASIC SCENARIO...ALTHOUGH THERE IS SOME SPREAD IN BOTH SPEED AND DIRECTION. THE OFFICIAL FORECAST IS ALONG THE SAME LINE AS THE PREVIOUS FORECAST FOR THE FIRST 48 HR BUT SOMEWHAT SLOWER. IT IS ALONG THE EASTERN EDGE OF THE MODEL GUIDANCE IN BEST AGREEMENT WITH THE GFS AND GFDL. AFTER 48 HR...THE FORECAST IS SHIFTED SOMEWHAT TO THE LEFT TO COMPROMISE BETWEEN THE GFS AND NOGAPS POSITIONS OF EXTRATROPICAL CHARLEY.
WHILE CHARLEY IS CURRENTLY STRENGTHENING SLOWLY...THERE IS STILL POTENTIAL FOR RAPID STRENGTHENING OVER THE SOUTHEASTERN GULF OF MEXICO GIVEN THE FAIRLY WELL-DEFINED EYE...THE WARM WATER AND THE GOOD TO EXCELLENT OUTFLOW IN THE NORTHERN SEMICIRCLE. ONE POTENTIAL NEGATIVE FACTOR IS A DRY SLOT WHICH HAS WRAPPED ALL THE WAY AROUND INNER CORE. THE SHIPS MODEL TAKES CHARLEY TO 97 KT IN 24 HR...WHILE THE GFDL BEINGS IT TO 112 KT. THE LATTER IS CERTAINLY POSSIBLE IF THE INTENSIFICATION RATE INCREASES. THE INTENSITY FORECAST CALL FOR CHARLEY TO PEAK AT 105 KT PRIOR TO LANDFALL...BUT IT COULD BE STRONGER. AFTER LANDFALL...PASSAGE OVER LAND AND INCREASING SHEAR SHOULD WEAKEN THE CYCLONE AND EVENTUALLY CAUSE EXTRATROPICAL TRANSITION.
THE POSSIBILITY OF A PREMATURE NORTHWARD MOTION AND THE FORECAST SIZE OF THE STORM REQUIRES TROPICAL STORM WATCHES TO BE EXTENDED SOUTHWARD ALONG THE SOUTHEAST FLORIDA COAST. THE FORECAST TRACK REQUIRES EXTENSION OF HURRICANE WARNINGS UP THE FLORIDA WEST COAST AND TROPICAL STORM WATCHES INTO SOUTH CAROLINA.
SINCE THE REST OF THE ADVISORY WAS TRANSMITTED...THE AIRCRAFT HAS FOUND THAT THE CENTRAL PRESSURE HAS DROPPED TO 973 MB.
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