255 
 WTNT43 KNHC 011441
 TCDAT3
 TROPICAL STORM FIONA DISCUSSION NUMBER   8
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082010
 1100 AM AST WED SEP 01 2010
  
 EARLIER THIS MORNING...THE AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT
 MEASURED A PEAK 850 MB WIND OF 58 KT...BELIEVABLE SFMR VALUES OF
 45-50 KT...AND A MINIMUM PRESSURE OF 998 MB.  THIS WAS THE BASIS FOR
 THE 8 AM INTENSITY OF 50 KT.  SINCE THAT TIME... THE SYSTEM HAS
 BECOME MORE DISORGANIZED WITH THE CENTER ON THE NORTHWESTERN EDGE OF
 WEAKENING DEEP CONVECTION.  ANOTHER AIRCRAFT WILL BE IN THE SYSTEM
 EARLY THIS AFTERNOON.  DESPITE MODERATE SHEAR...ALL OF THE
 GUIDANCE SHOW FURTHER INTENSIFICATION AND MOST ACTUALLY MAKE FIONA
 A HURRICANE.  BY LATE TOMORROW...THE SHEAR SHOULD INCREASE AS THE
 MAJORITY OF THE GLOBAL MODELS HAVE FAIRLY STRONG NORTHEASTERLY
 SHEAR IN A FEW DAYS DUE PRIMARILY TO STRONG UPPER-LEVEL WINDS FROM
 EARL. THIS PATTERN CAUSES FIONA TO RAPIDLY WEAKEN IN 3 OR 4
 DAYS...AND THE NHC FORECAST WILL STAY ON THE LOWER END OF THE
 GUIDANCE ENVELOPE...FAIRLY CLOSE TO THE SHIPS MODEL.
  
 AIRCRAFT FIXES SHOW A MOTION OF ABOUT 305/15 DURING THE PAST SEVERAL
 HOURS. TRACK MODELS ARE IN GOOD AGREEEMENT ON A NORTHWEST TO
 NORTH-NORTHWEST MOTION FOR A DAY OR TWO DUE TO FIONA MOVING AROUND
 A SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC OCEAN. HOWEVER...THE
 GUIDANCE STARTS TO BECOME RATHER DIVERGENT AFTER THAT TIME...WHICH
 APPEARS TO BE RELATED TO THE FUTURE INTENSITY OF FIONA. IF THE
 STORM WEAKENS QUICKLY...THE LOW-LEVEL CIRCULATION WILL LIKELY GET
 CAUGHT UP IN SOUTHWESTERLY FLOW AHEAD OF EARL. HOWEVER...IF FIONA
 STAYS A MORE COHERENT VORTEX...THERE REMAINS THE POTENTIAL FOR IT
 TO GET TRAPPED BY A MID-LEVEL SUBTROPICAL RIDGE. GIVEN THE STRONG
 SHEAR FORECAST AT THE END...THE NHC FORECAST LEANS TOWARD THE
 FASTER TRACK SCENARIO AT THE END OF THE FORECAST PERIOD AND
 IS CLOSE TO THE PREVIOUS FORECAST. HOWEVER...I DO NOT HAVE A LOT OF
 CONFIDENCE IN THE LONG-TERM TRACK OR INTENSITY FORECASTS...AS THE
 MODELS HAVE BEEN STURGGLING WITH CONSISTENCY WITH THIS STORM.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      01/1500Z 18.8N  61.7W    50 KT
  12HR VT     02/0000Z 20.3N  63.3W    55 KT
  24HR VT     02/1200Z 22.6N  65.3W    55 KT
  36HR VT     03/0000Z 24.9N  66.6W    55 KT
  48HR VT     03/1200Z 26.9N  67.1W    45 KT
  72HR VT     04/1200Z 29.0N  67.0W    40 KT
  96HR VT     05/1200Z 31.0N  67.0W    30 KT
 120HR VT     06/1200Z...DISSIPATED
  
 $$
 FORECASTER BLAKE