732 
 WTNT41 KNHC 090911
 TCDAT1
 TROPICAL STORM FLORENCE DISCUSSION NUMBER  23
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062006
 500 AM EDT SAT SEP 09 2006
  
 AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT REACHED THE CENTER OF
 FLORENCE ABOUT 04Z...WITH A SECOND FIX ABOUT 0630Z.  THE AIRCRAFT
 MEASURED MINIMUM PRESSURES OF 998 AND 993 MB ON THE TWO FIXES...
 WITH MAXIMUM 850 MB FLIGHT-LEVEL WINDS OF 61 KT ABOUT 50 N MI
 NORTHEAST OF THE CENTER.  SATELLITE INTENSITY ESTIMATES ARE 65 KT
 FROM SAB AND AFWA...AND 55 KT FROM TAFB.  THE INITIAL INTENSITY
 REMAINS 55 KT FOR THIS ADVISORY.  IT SHOULD BE NOTED THAT THE
 AIRCRAFT AND RECENT AMSR-E DATA SHOW THAT WHILE THE CONVECTION IS
 STRONG...IT IS CURRENTLY CONFINED TO THE NORTHERN QUADRANT.
 
 THE AIRCRAFT FOUND THE CENTER SOUTH OF THE PREVIOUS FORECAST
 TRACK...AND A REVIEW OF EARLIER SATELLITE DATA SUGGESTS THAT
 FLORENCE HAS BEEN MOVING WEST-NORTHWESTWARD FOR THE PAST 12 HR OR
 SO.  THE INITIAL MOTION IS 300/12.  OTHER THAN THIS...THERE IS NO
 CHANGE IN THE FORECAST PHILOSOPHY.  WATER VAPOR IMAGERY SHOWS THAT
 FLORENCE IS APPROACHING THE WESTERN END OF A DEEP-LAYER RIDGE...
 WITH AN UPPER-LEVEL LOW SOUTHWEST OF THE STORM NEAR 21N71W AND A
 MID/UPPER-LEVEL SHORTWAVE TROUGH APPROACHING THE EAST COAST OF THE
 UNITED STATES.  THIS COMBINATION SHOULD TURN FLORENCE NORTHWARD
 DURING THE NEXT 12-36 HR...WITH THE STORM RECURVING NORTHEASTWARD
 IN DEEP-LAYER SOUTHWESTERLY FLOW THEREAFTER.  ALL MODEL GUIDANCE
 AGREES ON THE RECURVATURE...WITH LBAR CALLING FOR THE FARTHEST WEST
 RECURVATURE AT 68W.  THERE REMAINS SOME SPREAD IN THE MODEL
 GUIDANCE AFTER RECURVATURE.  THE NOGAPS...GFDN...GFDL...AND ECMWF
 BRING THE CENTER OVER SOUTHEASTERN NEWFOUNDLAND...WHILE THE
 REMAINDER OF THE GUIDANCE KEEPS IT SOUTHEAST OF THE ISLAND.  THE
 NEW FORECAST TRACK IS MOVED WESTWARD FOR THE FIRST 48 HR DUE TO THE
 CURRENT POSITION AND MOTION...AND NOW CALLS FOR FLORENCE TO PASS
 VERY NEAR BERMUDA IN 48-72 HR.  THE LATTER PART OF THE FORECAST IS
 SIMILAR TO THE PREVIOUS PACKAGE.  OVERALL...THE NEW FORECAST TRACK
 IS JUST TO THE LEFT OF THE MODEL CONSENSUS.
 
 ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE THAT THE
 VERTICAL SHEAR HAS DECREASED TO ABOUT 10 KT.  FLORENCE HAS ABOUT A
 48-60 HR WINDOW IN WHICH TO INTENSIFY BEFORE ENCOUNTERING STRONG
 SHEAR IN THE WESTERLIES.  THE SHIPS AND FSU SUPERENSEMBLE BOTH
 FORECAST A PEAK INTENSITY OF 100-105 KT IN ABOUT 60 HR...WHILE THE
 GFDL CALLS FOR A PEAK INTENSITY OF 87 KT.  THE INTENSITY FORECAST
 IS AN UPDATE OF THE PREVIOUS PACKAGE...CALLING FOR A PEAK INTENSITY
 OF 90 KT IN ABOUT 48 HR.  AFTER FLORENCE ENTERS THE WESTERLIES...
 INCREASING VERTICAL SHEAR AND COLD AIR INTRUSION SHOULD CAUSE
 WEAKENING AND EXTRATROPICAL TRANSITION BY 120 HR.  HOWEVER...
 FLORENCE SHOULD REMAIN A LARGE AND VIGOROUS CYCLONE THROUGH THE
 TRANSITION PROCESS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      09/0900Z 24.1N  62.8W    55 KT
  12HR VT     09/1800Z 25.1N  64.3W    65 KT
  24HR VT     10/0600Z 26.7N  65.4W    75 KT
  36HR VT     10/1800Z 28.6N  65.9W    85 KT
  48HR VT     11/0600Z 30.6N  65.8W    90 KT
  72HR VT     12/0600Z 36.0N  63.0W    85 KT
  96HR VT     13/0600Z 43.0N  56.0W    70 KT...BECOMING EXTRATROPICAL
 120HR VT     14/0600Z 49.0N  46.0W    60 KT...EXTRATROPICAL
  
 $$
 FORECASTER BEVEN