770 
 WTNT45 KNHC 151451
 TCDAT5
 HURRICANE OMAR DISCUSSION NUMBER   9
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
 1100 AM EDT WED OCT 15 2008
  
 ON ITS FINAL LEG AROUND 11Z...AN AIR FORCE HURRICANE HUNTER AIRCRAFT
 REPORTED A PEAK SFMR SURFACE WIND OF 70 KT IN THE NORTHWEST
 QUADRANT OF OMAR'S EYEWALL. THIS WAS COINCIDENT WITH A NEARBY
 DROPSONDE SURFACE WIND VALUE OF 68 KT...SO THE INTENSITY AT THE 12Z
 SYNOPTIC TIME WAS INCREASED TO 70 KT. HOWEVER...SINCE THE LAST
 RECON FLIGHT...THE EYE HAS BECOME EVIDENT IN VISIBLE SATELLITE
 IMAGERY...AND ALSO IN THE SAN JUAN DOPPLER WEATHER RADAR DATA AT A
 RANGE OF MORE THAN 200 NMI. SATELLITE INTENSITY ESTIMATES ARE A
 CONSENSUS T4.5/77 KT FROM TAFB AND SAB...SO THE ADVISORY INTENSITY
 HAS BEEN INCREASED TO 75 KT BASED ON THE IMPROVED SATELLITE AND
 RADAR SIGNATURES.
 
 THE INITIAL MOTION ESTIMATE IS 045/08. THERE IS NO SIGNIFICANT
 CHANGE TO THE PREVIOUS TRACK FORECAST OR PHILOSOPHY. OMAR IS
 BASICALLY ON THE PREVIOUS ADVISORY TRACK...AND THE NHC MODEL
 GUIDANCE REMAINS TIGHTLY CLUSTERED ABOUT A NORTHEASTWARD MOTION
 THROUGH THE NORTHERN LEEWARD ISLANDS AND THE VIRGIN ISLANDS IN
 ABOUT 24 HOURS. AFTER THAT...OMAR IS EXPECTED TO ACCELERATE AS IT
 GETS CAUGHT UP IN THE STRONG SOUTHWESTERLY FLOW ON THE EAST SIDE OF
 A LARGE DEEPENING MID-TROPOSPHERIC TROUGH LOCATED OVER THE WESTERN
 ATLANTIC. A PIECE OF THE TROUGH BREAKS OFF AND LIFTS OUT TO THE
 NORTHEAST IN 72-96 HOURS...WHICH BRIEFLY WEAKENS THE STEERING FLOW.
 AFTER THAT...HOWEVER...THE MID-LATITUDE WESTERLIES ARE FORECAST TO
 INCREASE AHEAD OF A STRONGER LOW PRESSURE SYSTEM...WHICH IS
 EXPECTED TO ACCELERATE OMAR TO THE EAST-NORTHEAST AT 35-40 KT. THE
 OFFICIAL FORECAST TRACK WAS NUDGED A LITTLE TO THE LEFT OF THE
 PREVIOUS TRACK AND REMAINS SLOWER THAN THE NHC MODEL CONSENSUS.
  
 NOW THAT A DISTINCT EYE AND EYEWALL HAVE DEVELOPED...A GOOD CHIMNEY
 EFFECT CAN BE ESTABLISHED AND OMAR COULD GO THROUGH A BRIEF PERIOD
 OF RAPID INTENSIFICATION AGAIN. ONLY THE GFDL MODEL IS CALLING FOR
 OMAR TO STRENGTHEN TO AT LEAST 90 KT. THE REMAINDER OF THE
 INTENSITY GUIDANCE HOLDS OMAR BELOW 80 KT. BASED ON THE BETTER
 DEFINED EYE FEATURE...AND THE FACT THAT OMAR IS A RELATIVELY LOW
 SHEAR ENVIRONMENT AND OVER 29C AND WARMER SSTS...ADDITIONAL
 INTENSIFICATION SIMILAR TO THE GFDL MODEL SEEMS QUITE REASONABLE.
 IT ALSO ISN'T OUT OF THE QUESTION THAT OMAR COULD ACHIEVE MAJOR
 HURRICANE STATUS JUST BEFORE THE CYCLONE REACHES THE NORTHERN
 LEEWARD ISLANDS. HOWEVER...THE RAPID ENCROACHMENT OF DRY MID-LEVEL
 AIR FROM THE NORTHWEST AS NOTED IN WATER VAPOR SATELLITE IMAGERY
 PRECLUDES EXPLICITLY FORECASTING THAT INTENSITY AT THIS TIME SINCE
 THAT DRY AIR COULD MAKE IT INTO THE INNER CORE REGION IN 12-18
 HOURS AND WEAKEN THE HURRICANE.
  
 ALTHOUGH THE OFFICIAL FORECAST KEEPS THE CENTER EAST OF PUERTO
 RICO...ONLY A SLIGHT DEVIATION TO THE LEFT OF THE CURRENT MOTION
 COULD REQUIRE CHANGING THE HURRICANE WATCH TO A HURRICANE WARNING
 FOR THAT ISLAND.  ALSO...STRONGER WINDS...POSSIBLY ONE CATEGORY
 HIGHER...CAN BE EXPECTED OVER HIGHER TERRAIN...ESPECIALLY ABOVE 500
 FT ELEVATION.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      15/1500Z 15.2N  67.2W    75 KT
  12HR VT     16/0000Z 16.6N  65.9W    80 KT
  24HR VT     16/1200Z 19.1N  63.9W    90 KT...NRN LEEWARD ISLANDS
  36HR VT     17/0000Z 22.0N  61.8W    90 KT
  48HR VT     17/1200Z 24.7N  60.2W    85 KT
  72HR VT     18/1200Z 30.0N  56.5W    75 KT
  96HR VT     19/1200Z 37.0N  48.5W    65 KT
 120HR VT     20/1200Z 45.0N  32.5W    55 KT...EXTRATROPICAL
  
 $$
 FORECASTER STEWART