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#106289 (Received by flhurricane at: 5:08 PM 26.Aug.2006) TCDAT5 TROPICAL STORM ERNESTO DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL052006 500 PM EDT SAT AUG 26 2006 ON A MISSION THAT FEATURED A SATCOM FAILURE...AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT REPORTED THAT THE CENTER OF ERNESTO WAS WELL EAST-NORTHEAST OF THE INTERMEDIATE ADVISORY POSITION. HOW MUCH OF THIS IS DUE TO RE-FORMATION OF THE CENTER AND HOW MUCH IS DUE TO AN ACTUAL TRACK CHANGE IS UNCLEAR. THE AIRCRAFT REPORTED A CENTRAL PRESSURE OF 997 MB...AND A DROPWINDSONDE NORTHEAST OF THE CENTER SHOWED THAT THE MAXIMUM WINDS HAVE INCREASED TO AT LEAST 50 KT. WHILE THE RE-FORMATION PUTS THE CENTER CLOSER TO THE CONVECTION...ERNESTO IS STILL ENCOUNTERING NOTABLE WESTERLY TO SOUTHWESTERLY VERTICAL WIND SHEAR. THE INITIAL MOTION IS A VERY UNCERTAIN 295/11. WHILE THE OVERALL SYNOPTIC PATTERN IS UNCHANGED FROM THE PREVIOUS ADVISORY...THE REFORMATION OF THE CENTER REQUIRES SHIFTING THE FIRST 72 HR OF THE TRACK ABOUT 50 N MI NORTHEAST OF THE PREVIOUS TRACK. THIS INCREASES THE THREAT TO HAITI...THE DOMINICAN REPUBLIC...CUBA...AND THE FLORIDA KEYS. IT SHOULD BE NOTED THAT THE GFS SOLUTION OF BRINGING THE LOW-LEVEL CENTER OF ERNESTO TO SOUTH FLORIDA LOOKS DUBIOUS...AS THE 500 MB CENTER STAYS WELL TO THE SOUTH OVER CUBA. AFTER 72 HR...THE LARGE-SCALE MODELS ARE COMING INTO BETTER AGREEMENT THAT THE MID-LEVEL RIDGE OVER THE GULF OF MEXICO WILL BE BROKEN BY A SHORTWAVE TROUGH MOVING SOUTHEASTWARD FROM THE MISSISSIPPI VALLEY INTO THE SOUTHEASTERN STATES. THIS SHOULD ALLOW ERNESTO TO TURN NORTHWARD OVER THE CENTRAL OR EASTERN GULF OF MEXICO...ALTHOUGH THERE ARE STILL DIFFERENCES IN SPEED BETWEEN THE SLOWER UKMET AND ECMWF AND THE FASTER NOGAPS. THE LATTER PART OF THE FORECAST TRACK CALLS FOR A GRADUAL TURN TOWARD THE NORTH AT A SLOW SPEED...SIMILAR TO BUT EAST OF THE PREVIOUS FORECAST. MORE ADJUSTMENTS OF THE FORECAST TRACK MAY NECESSARY ON THE NEXT ADVISORY DEPENDING ON ANY NEW JUMPS IN THE CENTER POSITION TONIGHT. THE LARGE-SCALE MODELS CONTINUE TO FORECAST THE DEVELOPMENT OF A LARGE UPPER-LEVEL ANTICYCLONE ALONG THE FORECAST TRACK...ALTHOUGH SO FAR THEY HAVE BEEN TOO FAST IN DOING SO. IF THE MODELS ARE CORRECT...THE SHEAR SHOULD DIMINISH DURING THE NEXT 12-24 HR AND ALLOW ERNESTO TO STRENGTHEN. THE INTENSITY FORECAST CALLS FOR SLOW STRENGTHENING DURING THE FIRST 24 HR...AND STEADY STRENGTHENING THEREAFTER. THE INTENSITY FORECAST CALLS FOR ERNESTO TO REACH 105 KT INTENSITY IN 120 HR...SLIGHTLY STRONGER THAN THE SHIPS MODEL... AND THE STORM COULD GET STRONGER THAN THAT. ONE POTENTIAL PROBLEM WITH THE INTENSITY FORECAST IS INTERACTION WITH LAND...AS ERNESTO MIGHT NOT STRENGTHEN AS MUCH AS FORECAST IF IT GETS TOO CLOSE TO HISPANIOLA OR CUBA. IN SUMMARY...ERNESTO COULD BECOME A POTENTIALLY DANGEROUS HURRICANE AS IT MOVES ACROSS THE NORTHWESTERN CARIBBEAN SEA AND THE GULF OF MEXICO. INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM. FORECAST POSITIONS AND MAX WINDS INITIAL 26/2100Z 15.9N 71.6W 50 KT 12HR VT 27/0600Z 16.8N 73.3W 50 KT 24HR VT 27/1800Z 18.1N 75.4W 60 KT 36HR VT 28/0600Z 19.4N 77.6W 70 KT 48HR VT 28/1800Z 20.8N 79.8W 80 KT 72HR VT 29/1800Z 23.5N 83.5W 85 KT 96HR VT 30/1800Z 25.5N 86.0W 95 KT 120HR VT 31/1800Z 28.0N 87.0W 105 KT |