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| #212080 (Received by flhurricane at: 4:56 PM 31.Aug.2008) TCDAT2 HURRICANE GUSTAV DISCUSSION NUMBER 29 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072008 500 PM EDT SUN AUG 31 2008 VISIBLE SATELLITE IMAGERY DURING THE PAST COUPLE OF HOURS SUGGESTS THAT GUSTAV IS GETTING A LITTLE BETTER ORGANIZED...WITH A HINT OF AN EYE RETURNING. ADDITIONALLY...THE CENTRAL PRESSURE REPORTED BY AN AIR FORCE RESERVE HURRICANE HUNTER HAS FALLEN TO 957 MB. ON THE OTHER HAND...THE MAXIMUM 700 MB FLIGHT-LEVEL WINDS WERE 105 KT WHILE THE MAXIMUM SFMR WINDS WERE 93 KT. ALSO...THE CONVECTION...WHILE VIGOROUS...IS STILL RATHER ASYMMETRIC AROUND THE 30 NM WIDE EYE THAT IS OPEN TO THE SE. BASED ON THE AIRCRAFT DATA...THE INITIAL INTENSITY IS LOWERED TO 100 KT. THE INITIAL MOTION IS WOBBLING BETWEEN 315 AND 320 DEGREES AT 15-16 KT...WITH 320/16 BEING THE ADVISORY MOTION. THERE IS NO CHANGE IN THE TRACK FORECAST PHILOSOPHY...WITH A MID-LEVEL RIDGE OVER THE EASTERN UNITED STATES EXPECTED TO STEER GUSTAV NORTHWESTWARD INTO THE NORTHERN GULF COAST. THE NEW GUIDANCE RUNS...MOST NOTABLY THE HWRF...SHOW A SLIGHT LEFT TURN AFTER 12 HR WITH A LEFTWARD SHIFT IN THE LANDFALL POINT ON THE LOUISIANA COAST. THE NEW FORECAST TRACK IS SHIFTED SLIGHTLY TO THE LEFT OF THE PREVIOUS TRACK...AND SINCE IT LIES NEAR THE EASTERN EDGE OF THE GUIDANCE ENVELOPE SOME ADDITIONAL SMALL SHIFTS MAY BE NECESSARY LATER. AFTER 48-72 HR...THERE REMAINS MAJOR DISAGREEMENT BETWEEN THE DYNAMICAL MODELS ON WHETHER GUSTAV WILL RECURVE INTO THE WESTERLIES...SHEAR APART AND STALL OVER LOUISIANA OR TEXAS...OR TURN SOUTHWESTWARD. THE FORECAST TRACK AFTER 72 HR FOLLOWS THE SHEAR-APART-AND-STALL SCENARIO...CALLING FOR GUSTAV TO MOVE SLOWLY WESTWARD AS IT WEAKENS OVER LAND. ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE THAT GUSTAV REMAINS IN ABOUT 20 KT OF SOUTHERLY SHEAR...WITH A LOT OF MID/UPPER-LEVEL DRY AIR SEEN IN WATER VAPOR IMAGERY SOUTH AND WEST OF THE CYCLONE. THE EYE HAS MOVED NORTHWEST OF THE DEEP WARM WATER OF THE LOOP CURRENT...AND THAT COMBINED WITH THE LIKELIHOOD OF CONTINUED SHEAR REDUCES THE CHANCES OF SIGNIFICANT INTENSIFICATION. THE SHIPS MODEL FORECASTS NO STRENGTHENING BEFORE LANDFALL...WHILE THE GFDL AND HWRF FORECAST ABOUT 10 KT OF STRENGTHENING. GIVEN THE FALLING PRESSURES AND THE COLD CONVECTION...THE INTENSITY FORECAST CALLS FOR WINDS TO INCREASE TO 110 KT BEFORE LANDFALL...WITH GUSTAV MAKING LANDFALL AS A MAJOR HURRICANE. GUSTAV SHOULD WEAKEN AFTER LANDFALL AND BECOME A REMNANT LOW IN ABOUT 120 HR. FORECAST POSITIONS AND MAX WINDS INITIAL 31/2100Z 26.4N 87.3W 100 KT 12HR VT 01/0600Z 27.9N 88.9W 110 KT 24HR VT 01/1800Z 29.4N 90.9W 100 KT...INLAND 36HR VT 02/0600Z 30.7N 92.7W 60 KT...INLAND 48HR VT 02/1800Z 31.5N 93.9W 35 KT...INLAND 72HR VT 03/1800Z 32.0N 95.0W 30 KT...INLAND 96HR VT 04/1800Z 32.0N 96.0W 25 KT...INLAND 120HR VT 05/1800Z 32.0N 96.5W 20 KT...INLAND REMNANT LOW $$ FORECASTER BEVEN |
