ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM HERNAN DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008 200 AM PDT FRI AUG 08 2008 THE CLOUD PATTERN HAS NOT CHANGED VERY MUCH DURING THE PAST SEVERAL HOURS AND DUE TO SHEAR...THE LOW-LEVEL CENTER STILL APPEARS TO BE LOCATED ON THE EDGE OF THE DEEP CONVECTION. LATEST MICROWAVE DATA REVEAL THAT THE LOW- AND MID -LEVEL CENTERS ARE A LITTLE MORE ALIGNED THAN A FEW HOURS AGO BUT MOST OF THE DEEP CONVECTION REMAINS SOUTH OF THE CENTER. THE OUTFLOW IS ESTABLISHED ONLY IN THE WESTERN SEMICIRCLE. DVORAK T-NUMBERS HAVE BEEN STEADY FOR ABOUT 18 HOURS SUGGESTING AN INITIAL INTENSITY OF 55 KNOTS. INTENSITY GUIDANCE IS NOT SHOWING ANY SIGNIFICANT INTENSIFICATION. IN FACT...MOST OF THE MODELS SUGGEST THAT HERNAN HAS PEAKED ALREADY. BASED ON CONTINUITY...THE OFFICIAL FORECAST STILL SHOWS A VERY MODEST STRENGTHENING DURING THE NEXT 24 HOURS BRINGING HERNAN TO HURRICANE STATUS. THIS IS BECOMING LESS LIKELY TO OCCUR SINCE THE SHEAR IS NOT RELAXING AS ANTICIPATED. A GRADUAL WEAKENING SHOULD BEGIN BEYOND 24-36 HOURS AS HERNAN APPROACHES COOLER WATERS. HERNAN HAS BEEN MOVING TOWARD THE WEST OR 270 DEGREES AT 11 KNOTS. HOWEVER...A WEAKNESS IN THE SUBTROPICAL RIDGE ALONG 130 DEGREES WEST WILL PROBABLY INDUCE A MORE WEST-NORTHWEST TRACK IN THE NEXT 2 TO 3 DAYS. THEREAFTER...HERNAN IS FORECAST TO WEAKEN AND BECOME STEERED WESTWARD OR EVEN SOUTH OF DUE WEST BY THE LOW-LEVEL FLOW. MOST OF THE TRACK GUIDANCE SHOWS THE INITIAL WEST-NORTHWEST TRACK AND THE TURN TO THE WEST AND WEST-SOUTHWEST BEYOND 96 HOURS...AND SO DOES THE OFFICIAL FORECAST. THE INITIAL WIND RADII WAS ADJUSTED USING LATEST AVAILABLE QUIKSCAT. FORECAST POSITIONS AND MAX WINDS INITIAL 08/0900Z 15.0N 118.9W 55 KT 12HR VT 08/1800Z 15.1N 120.4W 60 KT 24HR VT 09/0600Z 15.4N 122.2W 65 KT 36HR VT 09/1800Z 16.0N 124.0W 55 KT 48HR VT 10/0600Z 17.0N 125.5W 50 KT 72HR VT 11/0600Z 18.0N 128.5W 45 KT 96HR VT 12/0600Z 18.0N 131.5W 30 KT 120HR VT 13/0600Z 17.5N 134.0W 20 KT...REMNANT LOW $$ FORECASTER AVILA NNNN
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