|
Show Selection: |
| #531923 (Received by flhurricane at: 4:44 AM 05.Aug.2012) TCDAT5 TROPICAL STORM ERNESTO DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012 500 AM EDT SUN AUG 05 2012 DATA FROM THE LATEST HURRICANE HUNTER MISSION INTO ERNESTO SHOWED THAT THE CIRCULATION CONTINUES TO BE RATHER DISORGANIZED. THE CENTRAL PRESSURE ROSE TO 1009 MB ON THE LAST FIX AND THE AIRCRAFT FOUND ONLY VERY WEAK WESTERLY WINDS OF LESS THAN 5 KT NEAR THE CENTER. THE PEAK 850-MB FLIGHT LEVEL WIND WAS 52 KT AND THE HIGHEST SFMR WINDS WERE 40 TO 45 KT. BASED ON THESE DATA...THE INITIAL INTENSITY IS SET TO 45 KT. WHILE THE OUTFLOW REMAINS WELL ESTABLISHED...THE CONVECTIVE STRUCTURE OF THE CYCLONE HAS DEGRADED OVER THE PAST 6 TO 12 HOURS. RAOB DATA FROM CURACAO...MODEL ANALYSES AND AIRCRAFT DATA SHOW A TONGUE OF DRY AIR IN THE LOWER TO MID-TROPOSPHERE IMPINGING ON ERNESTO FROM THE SOUTH. THIS DRY AIR IN COMBINATION WITH SOME MID-LEVEL SHEAR ANALYZED BY UW-CIMSS MAY BE PARTLY RESPONSIBLE FOR THE LACK OF DEVELOPMENT IN THE LAST DAY OR SO. DESPITE OTHERWISE SEEMINGLY FAVORABLE CONDITIONS...THE GFDL AND HWRF NOW BOTH SHOW THE CYCLONE WEAKENING DURING THE NEXT 48 HOURS. THE SHIPS AND LGEM STILL SHOW INTENSIFICATION...BUT AT A SLOWER RATE COMPARED TO THEIR PREVIOUS FORECASTS. GIVEN THESE TRENDS...THE NEW NHC FORECAST HAS BEEN ADJUSTED DOWNWARD THROUGH 48 HOURS...BUT IS STILL ABOVE THE MULTI-MODEL CONSENSUS. AFTER THAT TIME THERE IS STILL AN OPPORTUNITY FOR ERNESTO TO BECOME A HURRICANE BEFORE REACHING LAND...WITH SOME RESTRENGTHENING POSSIBLE AFTER THE CYCLONE MOVES INTO THE GULF OF MEXICO BY DAY 5. THE LAST FEW AIRCRAFT PASSES THROUGH THE CENTER...SUCH AS IT IS... SHOWED THAT ERNESTO HAS ACCELERATED BACK TOWARD THE WEST...WITH AN INITIAL MOTION OF 275/19. THE INITIAL POSITION AND MOTION RESULTS IN A SHIFT IN THE NHC TRACK OF ABOUT A HALF A DEGREE TO THE LEFT... OR SOUTH...OF THE PREVIOUS FORECAST. APART FROM THIS ADJUSTMENT... THERE IS NO CHANGE TO THE OVERALL FORECAST REASONING. ERNESTO IS EXPECTED TO CONTINUE WESTWARD FOR THE NEXT DAY OR SO AND THEN SLOW DOWN AND TURN WEST-NORTHWESTWARD BY 48 HOURS AS A WEAKNESS DEVELOPS IN THE SUBTROPICAL RIDGE OVER THE EASTERN GULF OF MEXICO. THIS WEST-NORTHWESTWARD MOTION SHOULD CONTINUE THROUGH THE END OF THE PERIOD AS THE WEAKNESS PERSISTS OVER THE GULF. THE GFS...ECMWF... AND THE GFS ENSEMBLE MEAN LIE ON THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE...SHOWING LESS OF A NORTHWARD TURN AND A TRACK CLOSER TO THE COAST OF CENTRAL AMERICA AND INTO THE CENTRAL YUCATAN PENINSULA. THE GFDL...UKMET AND SOME OF THE HFIP MODELS...ARE FARTHER NORTH AND TAKE THE CYCLONE OVER THE NORTHERN YUCATAN AND INTO THE CENTRAL GULF. THROUGH 72 HOURS THE NHC FORECAST IS CLOSE TO THE MIDDLE OF THE GUIDANCE ENVELOPE AND THE MULTI-MODEL CONSENSUS. AT DAYS 4 AND 5 THE OFFICIAL FORECAST HEDGES TOWARD THE USUALLY RELIABLE GFS AND ECMWF MODELS AND IS A LITTLE SOUTH OF THE CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 15.1N 74.8W 45 KT 50 MPH 12H 05/1800Z 15.3N 77.5W 45 KT 50 MPH 24H 06/0600Z 15.6N 80.1W 50 KT 60 MPH 36H 06/1800Z 16.0N 82.1W 55 KT 65 MPH 48H 07/0600Z 16.6N 83.9W 60 KT 70 MPH 72H 08/0600Z 18.5N 87.5W 75 KT 85 MPH 96H 09/0600Z 20.5N 91.0W 60 KT 70 MPH 120H 10/0600Z 21.6N 94.0W 65 KT 75 MPH $$ FORECASTER BRENNAN |
