123 
 WTNT41 KNHC 281452
 TCDAT1
 TROPICAL STORM BETA DISCUSSION NUMBER   7
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 11 AM EDT FRI OCT 28 2005
  
 BETA IS GENERATING STRONG CENTRAL CONVECTION WITH TOPS TO -86C. 
 HOWEVER...OVERPASSES FROM AMSR-E AT 0705Z AND SSM/I AT 1148Z
 SUGGEST THE STORM HAS BECOME SOMEWHAT SHEARED...WITH THE CONVECTION
 DISPLACED SOUTH AND SOUTHWEST OF THE CENTER.  THERE ARE HINTS OF
 THIS IN VISIBLE IMAGERY AS WELL.  WHILE CIRRUS EAST OF BETA ARE
 BLOWING TOWARD THE CENTER...ANALYSES FROM CIMSS AT THE UNIVERSITY
 OF WISCONSIN SHOW ONLY ABOUT 10 KT OF SHEAR...WHICH IF CORRECT DOES
 NOT FULLY EXPLAIN THE APPARENT STRUCTURE.  SATELLITE INTENSITY
 ESTIMATES ARE 65 KT FROM TAFB...55 KT FROM SAB...AND 45 KT FROM
 AFWA.  THE INITIAL INTENSITY REMAINS 55 KT BASED ON A BLEND OF
 THESE AND A 50 KT REPORT AT 0900Z FROM SHIPS ZCAM4 JUST SOUTH OF
 THE CENTER.  AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT WILL
 INVESTIGATE BETA THIS AFTERNOON.
 
 THE INITIAL MOTION IS 360/4.  BETA IS MOVING NORTHWARD TOWARD A
 WEAKNESS IN THE SUBTROPICAL RIDGE CAUSED BY A DEEP-LAYER TROUGH
 OVER THE EASTERN UNITED STATES.  RAWINSONDE DATA AND WATER VAPOR
 IMAGERY INDICATE THAT A STRONG SHORTWAVE TROUGH IS MOVING EASTWARD
 ACROSS THE SOUTHEASTERN U. S. AND THE EASTERN GULF OF MEXICO.  THE
 DYNAMICAL MODELS FORECAST HEIGHTS TO RISE IN THESE AREAS AFTER THE
 TROUGH MOVES INTO THE ATLANTIC IN 12-24 HR.  SATELLITE IMAGERY AND
 SURFACE OBSERVATIONS ALSO SUGGEST THAT THE LOW-LEVEL RIDGE OVER THE
 WESTERN ATLANTIC AND NORTHERN CARIBBEAN IS BUILDING WESTWARD.  THIS
 EVOLUTION SHOULD TURN BETA MORE NORTHWESTWARD DURING THE NEXT 24 HR
 AND MORE WESTWARD THEREAFTER.  THE GFS...GFDL...NOGAPS...AND ECMWF
 ALL CALL FOR A VERY SHARP TURN...WHILE THE UKMET AND CANADIAN CALL
 FOR A MORE GRADUAL TURN.  THE NEW FORECAST TRACK IS SHIFTED A
 LITTLE MORE TO THE NORTH BASED ON THE CURRENT POSITION AND
 MOTION...CALLING FOR LANDFALL IN NORTHEASTERN NICARAGUA IN 36-48
 HR.  THE NEW TRACK IS SOUTH OF THE UKMET BUT NORTH OF THE OVERALL
 MODEL CONSENSUS.
  
 IF BETA IS AS SHEARED AS THE MICROWAVE DATA SUGGESTS...THEN THE
 SHORT-TERM INTENSIFICATION COULD BE SLOWER THAN CURRENTLY FORECAST. 
 THAT BEING SAID...THE SHIPS MODEL FORECASTS THE SHEAR TO DECREASE
 IN 12-18 HR...AND THE GFDL IS CALLING FOR BETA TO REACH 95 KT
 BEFORE LANDFALL.  THUS...THE INTENSITY FORECAST WILL CONTINUE TO
 CALL FOR BETA TO REACH CATEGORY TWO INTENSITY BEFORE LANDFALL.  THE
 CYCLONE SHOULD WEAKEN AFTER LANDFALL...AND IT COULD DISSIPATE
 FASTER THAN FORECAST OVER THE MOUNTAINS OF CENTRAL AMERICA.
  
 ONE OUTER RAINBAND IS CURRENTLY SPREADING ONSHORE IN NORTHEASTERN
 NICARAGUA AND EASTERN HONDURAS.  AS BETA GETS CLOSER TO THE CENTRAL
 AMERICAN COAST...THE THREAT OF HEAVY RAINS...FLOODS...AND MUDSLIDES
 WILL INCREASE.
  
 FORECASTER BEVEN
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      28/1500Z 12.9N  81.2W    55 KT
  12HR VT     29/0000Z 13.3N  81.2W    65 KT
  24HR VT     29/1200Z 13.9N  81.8W    75 KT
  36HR VT     30/0000Z 14.2N  82.6W    85 KT
  48HR VT     30/1200Z 14.6N  83.6W    80 KT...INLAND
  72HR VT     31/1200Z 15.0N  85.5W    30 KT...INLAND
  96HR VT     01/1200Z 15.0N  87.0W    25 KT...INLAND DISSIPATING
 120HR VT     02/1200Z 15.5N  88.5W    20 KT...INLAND REMNANT LOW
  
  
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