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| #54482 (Received by flhurricane at: 4:58 PM 28.Oct.2005) TCDAT1 TROPICAL STORM BETA DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT FRI OCT 28 2005 AN AIR FORCE RESERVE HURRICANE HUNTER HAS JUST MEASURED A CENTRAL PRESSURE OF 990 MB AND REPORTED A PARTIAL 15 N MI WIDE EYE. HOWEVER...THE MAXIMUM 850 MB FLIGHT-LEVEL WINDS ARE 51 KT...WHICH GENERALLY DOES NOT SUPPORT THE 55 KT INTENSITY SUGGESTED BY THE CENTRAL PRESSURE AND THE SATELLITE INTENSITY ESTIMATES. IT MAY BE THAT A TIGHTER INNER CORE EXISTED EARLIER AND WAS DISRUPTED BY THE NORTHEASTERLY SHEAR...AND IS JUST NOW COMING BACK TOGETHER. THE INITIAL INTENSITY WILL REMAIN 55 KT FOR THIS ADVISORY. THE INITIAL MOTION REMAINS 360/4. WHILE THE CENTER FIXES DO NOT YET SHOW A SIGNIFICANT WESTWARD COMPONENT TO THE MOTION...A NET NORTHWESTWARD SHIFT OF THE CLOUD MASS MAY BE A PRECURSOR OF THE EXPECTED NORTHWESTWARD TURN. WATER VAPOR IMAGERY INDICATES THAT A STRONG SHORTWAVE TROUGH IS MOVING EASTWARD ACROSS THE SOUTHEASTERN U. S. AND THE EASTERN GULF OF MEXICO. THE DYNAMICAL MODELS CONTINUE TO FORECAST HEIGHTS TO RISE IN THESE AREAS AFTER THE TROUGH MOVES INTO THE ATLANTIC IN 12-18 HR. SATELLITE IMAGERY AND SURFACE OBSERVATIONS ALSO SUGGEST THAT THE LOW-LEVEL RIDGE OVER THE WESTERN ATLANTIC AND NORTHERN CARIBBEAN IS SLOWLY BUILDING WESTWARD. THIS EVOLUTION SHOULD TURN BETA MORE NORTHWESTWARD DURING THE NEXT 12-24 HR AND MORE WESTWARD THEREAFTER. THE GFS...GFDL...AND NOGAPS MODELS STILL CALL FOR A WESTWARD TURN...ALTHOUGH ALL THREE ARE SOMEWHAT TO THE NORTH OF THEIR PREVIOUS RUNS. THE UKMET STILL CALLS FOR A MORE GRADUAL TURN...BUT STILL BRINGS BETA INLAND IN NICARAGUA. THE NEW FORECAST TRACK IS SHIFTED SLIGHTLY TO THE NORTH FOR THE FIRST 48 HR...CALLING FOR LANDFALL IN NORTHEASTERN NICARAGUA IN 36-48 HR. THE NEW TRACK REMAINS SOUTH OF THE UKMET AND JUST NORTH OF THE OVERALL MODEL CONSENSUS. ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE 15 KT OF EASTERLY VERTICAL SHEAR OVER BETA. THE SHIPS MODEL SUGGESTS THIS WILL PERSIST FOR 12 HR OR SO...AND THE INTENSITY FORECAST HAS BEEN REDUCED SLIGHTLY DURING THAT TIME. AFTER THE SHEAR DECREASES... CONDITIONS CONTINUE TO APPEAR FAVORABLE FOR RAPID STRENGTHENING... AND THE GFDL BRINGS A STRONG CATEGORY TWO HURRICANE INTO NICARAGUA. THUS...THE INTENSITY FORECAST CONTINUES TO CALL FOR BETA TO REACH 85 KT BEFORE LANDFALL. THE CYCLONE SHOULD WEAKEN AFTER LANDFALL... ESPECIALLY OVER THE CENTRAL AMERICAN MOUNTAINS...AND IT MAY BE THAT HANGING ON TO IT FOR 120 HR MAY BE GENEROUS. THE WIND RADII HAVE BEEN REDUCED DOWNWARD BASED ON SURFACE AND AIRCRAFT DATA. BETA HAS BEEN MUCH SLOWER TO GROW IN SIZE THAN ANTICIPATED...AND IT MAY BE THAT EVEN THE NEW FORECAST RADII ARE TOO LARGE. WHILE THE WINDS MAY SPREAD ONSHORE LATER THAN ORIGINALLY FORECAST...THE HEAVY RAINS WILL BE SPREADING INTO CENTRAL AMERICA STARTING TONIGHT. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 28/2100Z 13.3N 81.1W 55 KT 12HR VT 29/0600Z 13.8N 81.3W 60 KT 24HR VT 29/1800Z 14.3N 82.0W 70 KT 36HR VT 30/0600Z 14.6N 82.9W 85 KT 48HR VT 30/1800Z 14.8N 83.9W 65 KT...INLAND 72HR VT 31/1800Z 15.0N 86.0W 30 KT...INLAND 96HR VT 01/1800Z 15.0N 88.0W 25 KT...INLAND DISSIPATING 120HR VT 02/1800Z 16.0N 89.5W 20 KT...INLAND REMNANT LOW |
