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| #200664 (Received by flhurricane at: 4:55 PM 12.Jul.2008) TCDAT2 HURRICANE BERTHA DISCUSSION NUMBER 39 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 500 PM EDT SAT JUL 12 2008 AN AIR FORCE PLANE HAS COMPLETED TWO PASSES THROUGH THE EYE OF BERTHA AND THE MAXIMUM FLIGHT LEVEL WINDS WERE 79 AND 74 KT. THE SFMR ON BOARD OF THE PLANE DID NOT REPORT ANY HURRICANE FORCE WINDS...IN FACT...THE STRONGEST WINDS WERE 58 KNOTS IN THE SOUTHEAST QUADRANT. THE BEST ESTIMATE OF THE INITIAL INTENSITY IS 65 KNOTS...MAKING BERTHA BARELY A HURRICANE. ATMOSPHERIC CONDITIONS ARE NOT HOSTILE FOR SOME STRENGTHENING BUT BERTHA HAS BEEN LOCATED TOO MANY HOURS IN THE SAME AREA PRODUCING UPWELLING. THE HURRICANE HAS LOST A LOT OF THE DEEP CONVECTION BUT THE LOW-LEVEL CIRCULATION IS LARGE AND VIGOROUS WHILE THE OUTFLOW IS WELL ESTABLISHED. THEREFORE...BERTHA COULD GATHER SOME STRENGTH WHEN IT GETS OUT THAT AREA OF COOL WATERS INDUCED BY THE HURRICANE ITSELF. FOR NOW...BERTHA IS KEPT AS A 65 KNOT HURRICANE FOR A DAY OR TWO WITH A GRADUAL WEAKENING THEREAFTER DUE TO INCREASING SHEAR. BERTHA IS LIKELY TO BECOME LARGER AS IT GAINS LATITUDE AND BEGIN TO INTERACT WITH THE MID-LATITUDE FLOW. BERTHA HAS BARELY MOVED DURING THE DAY. THE PATTERN OF WEAK STEERING CURRENTS IS EXPECTED TO CONTINUE FOR THE NEXT DAY OR TWO....SO ONLY A PAINFULLY SLOW NORTHWARD MOTION IS ANTICIPATED. BEYOND THREE DAYS...BERTHA IS EXPECTED TO BE FULLY EMBEDDED WITHIN THE MID-LATITUDE CIRCULATION AND LOCATED BETWEEN AN EASTWARD MOVING TROUGH AND A LARGER CUT OFF LOW TO THE EAST. THIS PATTERN SHOULD FORCE BERTHA ON A SLOW EASTWARD TRACK. THIS IS THE SOLUTION PROVIDED MY MOST OF THE GLOBAL MODELS AS WELL AS THE DYNAMICAL TRACK GUIDANCE. FORECAST POSITIONS AND MAX WINDS INITIAL 12/2100Z 29.9N 62.6W 65 KT 12HR VT 13/0600Z 30.4N 62.7W 65 KT 24HR VT 13/1800Z 31.0N 62.7W 65 KT 36HR VT 14/0600Z 32.0N 62.8W 65 KT 48HR VT 14/1800Z 33.0N 62.8W 60 KT 72HR VT 15/1800Z 34.5N 61.5W 55 KT 96HR VT 16/1800Z 35.5N 59.0W 50 KT 120HR VT 17/1800Z 35.5N 56.0W 50 KT $$ FORECASTER AVILA |
