251 
 WTNT43 KNHC 031500
 TCDAT3
 TROPICAL STORM HANNA DISCUSSION NUMBER  27
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
 1100 AM EDT WED SEP 03 2008
  
 THERE HAVE BEEN SOME STRUCTURAL CHANGES WITH HANNA TODAY AS IT
 INTERACTS WITH THE UPPER-LEVEL LOW MOVING THROUGH THE NORTHWESTERN
 BAHAMAS.  THE WIND FIELD HAS EXPANDED IN THE NORTHERN SEMICIRCLE
 AND THE LOW-LEVEL CIRCULATION CENTER HAS BECOME LESS WELL DEFINED. 
 VISIBLE IMAGERY SUGGESTS MULTIPLE LOW-LEVEL SWIRLS COMING OUT OF
 THE DEEP CONVECTION TO THE NORTH OF A MEAN CENTER...AND THE
 SYSTEM'S CONVECTIVE BANDS ARE WELL REMOVED FROM THE CORE.  THE
 RECONNAISSANCE MISSION THAT ENDED AROUND 12Z REPORTED SOME SFMR
 WINDS OF UP TO 45 KT ABOUT 70 NM FROM THE CENTER...AND THE INITIAL
 INTENSITY ESTIMATE REMAINS 50 KT.
 
 BECAUSE THE CENTER IS NOT WELL DEFINED...THE INTIAL MOTION IS HARD
 TO GAUGE.  MY BEST ESTIMATE IS 360/5...AND THIS COULD BE THE START
 OF THE EXPECTED NORTHWESTWARD TURN.  THE STEERING FLOW SHOULD
 BECOME BETTER DEFINED OVER THE NEXT 24-48 HOURS AS THE UPPER LOW
 MOVES WEST-SOUTHWESTWARD AND MID-LEVEL RIDGING BUILDS IN BEHIND THE
 LARGE DEEP-LAYER LOW OFF THE UPPER U.S. EAST COAST.  MODEL GUIDANCE
 RESPONDS TO THIS PATTERN WITH A NORTHWESTWARD ACCELERATION WITH A
 RECURVATURE AROUND THE MID-LEVEL RIDGE IN ABOUT THREE DAYS.  THE
 GUIDANCE HAS BEEN TOO FAST WITH THIS SCENARIO OVER THE PAST COUPLE
 OF DAYS...AND GIVEN THE POOR CORE STRUCTURE OF HANNA I AM INCLINED
 TO THINK THAT SUBSEQUENT INTERACTION WITH THE UPPER STEERING MAY BE
 A LITTLE OVERDONE...AT LEAST INITIALLY.  THE OFFICIAL FORECAST IS
 IN BEST AGREEMENT WITH THE ECMWF AND UKMET IN TERMS OF SPEED...WITH
 THE GFS/HWRF/GFDL SHOWING A MORE VERTICAL SYSTEM MOVING MORE
 RAPIDLY.  THE GUIDANCE HAS ALSO BEEN TRENDING EASTWARD OVER THE
 PAST FEW CYCLES...AND I HAVE SHIFTED THE TRACK SLIGHTLY IN THAT
 DIRECTION.
 
 WESTERLY SHEAR AND DRY AIR ASSOCIATED WITH THE UPPER LOW WILL
 INHIBIT DEVELOPMENT IN THE SHORT TERM BUT SHOULD DIMINISH OVER THE
 NEXT COUPLE OF DAYS...TO BE REPLACED WITH MODERATE SOUTHEASTERLY
 SHEAR.  THIS PATTERN WOULD PERMIT SOME RE-INTENSIFICATION...BUT
 HANNA WILL NEED TO RECREATE AN INNER CORE IN ORDER TO INTENSIFY
 SUBSTANTIALLY.  THE AVAILABLE GUIDANCE STILL BRINGS HANNA TO
 MINIMAL HURRICANE INTENSITY AND THE OFFICIAL FORECAST IS JUST ABOVE
 THIS GUIDANCE.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      03/1500Z 20.6N  71.8W    50 KT
  12HR VT     04/0000Z 21.5N  72.0W    50 KT
  24HR VT     04/1200Z 23.4N  73.3W    55 KT
  36HR VT     05/0000Z 25.2N  75.2W    60 KT
  48HR VT     05/1200Z 27.3N  77.1W    65 KT
  72HR VT     06/1200Z 33.0N  79.0W    70 KT
  96HR VT     07/1200Z 42.0N  71.0W    35 KT...INLAND EXTRATROPICAL
 120HR VT     08/1200Z 47.0N  60.0W    35 KT...EXTRATROPICAL
  
 $$
 FORECASTER FRANKLIN
  
 
 
 594 
 WTNT44 KNHC 031500
 TCDAT4
 TROPICAL STORM IKE DISCUSSION NUMBER   9
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL092008
 1100 AM EDT WED SEP 03 2008
  
 IKE IS WRAPPING UP SOME SOLID CONVECTIVE BANDING AS VIEWED IN
 VISIBLE IMAGERY...AND SINCE A PARTIAL OVERPASS SEVERAL HOURS AGO
 FROM AMSR-E SUGGESTED A MICROWAVE EYE WAS FORMING...WE MIGHT SEE AN
 EYE IN THE VISIBLE BEFORE TOO MUCH LONGER.  SUBJECTIVE DVORAK
 T-NUMBERS AT 1200 UTC WERE A CONSENSUS 4.0...BUT OBJECTIVE NUMBERS
 ARE A LITTLE LOWER...SO THE INTENSITY IS SET TO 60 KT FOR NOW.  IN
 ANY CASE...IKE IS ON THE CUSP OF BEING A HURRICANE AND SHOULD BE
 ONE LATER TODAY.  THE UNDERLYING OCEAN TEMPERATURES WILL ONLY GET
 WARMER ALONG THE FORECAST TRACK...MAXIMIZING BEYOND 48 HOURS NEAR
 29 CELSIUS...WHICH WOULD FAVOR A STRENGTHENING TREND THROUGHOUT THE
 FIVE-DAY PERIOD.  DURING THE NEXT COUPLE OF DAYS...HOWEVER...IKE
 MIGHT ENCOUNTER A LITTLE INCREASE IN WIND SHEAR FROM THE NORTH
 BEHIND THE MID-LATITUDE TROUGH THAT WILL BE TRAVERSING THE
 NORTHWESTERN ATLANTIC.  THE OBJECTIVE GUIDANCE DOES NOT FORECAST
 ANY WEAKENING AS A RESULT...BUT NONE OF THE MODELS FORECAST ROBUST
 STRENGTHENING...UNTIL IKE HEADS FARTHER WEST...ESCAPES THE
 SHEAR...AND MOVES OVER EVEN WARMER WATERS NEAR THE GREATER
 ANTILLES.  STEADY STRENGTHENING IS FORECAST AT DAYS 3-5 IN LINE
 WITH MOST OF THE INTENSITY MODELS...AND IKE COULD REACH MAJOR
 HURRICANE STATUS BEFORE FIVE DAYS PASS.
 
 IKE CONTINUES WEST-NORTHWESTWARD OR 285/16 ALONG THE SOUTHWESTERN
 PERIPHERY OF A MID-LEVEL RIDGE OVER THE CENTRAL ATLANTIC.  THE
 MODELS FORECAST IKE TO BEND A LITTLE TO THE RIGHT AROUND THAT
 RIDGE...BUT IN A COUPLE OF DAYS IT WILL RUN INTO A RIDGE BUILDING
 OVER THE WESTERN ATLANTIC.  NEARLY ALL OF THE MODELS AGREE THAT
 THIS PATTERN WILL FORCE IKE WEST-SOUTHWESTWARD AND EVENTUALLY
 WESTWARD AROUND THE SOUTHERN PERIPHERY OF THAT FEATURE...BUT THEY
 DO NOT AGREE ON THE EXACT LATITUDE OR THE SPEED OF THAT WESTWARD
 MOTION.  THE CONSENSUS HAS SLOWED DOWN A LITTLE LATE IN THE
 FIVE-DAY PERIOD...AND SO HAS THE OFFICIAL FORECAST TRACK...BUT
 OTHERWISE THE NEW TRACK IS SIMILAR TO THE PREVIOUS ONE...EXCEPT FOR
 A LITTLE MORE NORTHWARD PROGRESS WITHIN THE NEXT COUPLE OF DAYS.
  
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      03/1500Z 20.8N  51.2W    60 KT
  12HR VT     04/0000Z 21.7N  53.7W    65 KT
  24HR VT     04/1200Z 23.1N  56.8W    70 KT
  36HR VT     05/0000Z 23.8N  59.4W    70 KT
  48HR VT     05/1200Z 24.0N  62.0W    70 KT
  72HR VT     06/1200Z 22.5N  67.0W    80 KT
  96HR VT     07/1200Z 22.0N  71.5W    90 KT
 120HR VT     08/1200Z 22.5N  75.5W   100 KT
  
 $$
 FORECASTER KNABB