494 
 WTNT45 KNHC 161513
 TCDAT5
 HURRICANE OMAR DISCUSSION NUMBER  13
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
 1100 AM EDT THU OCT 16 2008
  
 IT IS SIMPLY AMAZING TO ME AT HOW QUICKLY A HURRICANE CAN SPIN UP
 AND JUST AS QUICKLY FALL APART.  OMAR REACHED NEAR THE THRESHOLD OF 
 CATEGORY 4 EARLY THIS MORNING AROUND 06Z AND NOW WE HAVE AN EXPOSED
 LOW-LEVEL CENTER SHOWING UP IN THE VISIBLE SATELLITE IMAGERY JUST A
 FEW HOURS LATER.  SUBJECTIVE AND OBJECTIVE DVORAK TECHNIQUES WERE
 SUGGESTING AROUND 90-100 KT AT 12Z.  BUT GIVEN THE RAPID
 DETERIORATION OF THE CONVECTIVE SIGNATURE...THE CURRENT INTENSITY
 IS ESTIMATED...WITH SIGNIFICANT UNCERTAINTY...TO BE 75 KT.
 
 DESPITE VERY WARM WATERS...THE COMBINATION OF STRONG VERTICAL SHEAR
 AND LOW TO MID-LEVEL DRY AIR...AS SEEN IN THE TOTAL PRECIPITABLE
 WATER IMAGERY...HAS PRODUCED THE WEAKENING IN OMAR AND WILL LIKELY
 CONTINUE TO CAUSE A DECREASE IN ITS INTENSITY.  BECAUSE THE TREND
 OF OMAR'S INTENSITY WAS NOT CORRECTLY ANALYZED AT SYNOPTIC
 TIME...THE STATISTICAL MODELS...SHIPS AND LGEM...ARE PROVIDING
 VALUES THAT ARE PROBABLY TOO HIGH.  THE FORECAST IS CLOSEST TO THE
 HWRF MODEL WHICH DID VERY WELL IN ANTICIPATING THIS MORNING'S RAPID
 WEAKENING OF OMAR.  AS THE CYCLONE BECOMES EXTRATROPICAL AROUND DAY
 4...IT DOES NOT APPEAR THAT SIGNIFICANT RE-INTENSIFICATION WILL
 TAKE PLACE AT THAT TIME BASED UPON THE GLOBAL MODELS' CONSENSUS.
 
 THE NOW EASY-TO-SEE CENTER DID FORCE US TO MAKE A LAST SECOND
 RELOCATION OF THE INITIAL POSITION AS WELL AS THE SHORT TERM TRACK
 FORECAST TO ACCOUNT FOR THE MORE SOUTHERN LOCATION THAN AT FIRST
 ESTIMATED.  THE TRACK GUIDANCE IS CLOSELY CLUSTERED THROUGH 72
 HR...BUT THEN SHOWS SIGNIFICANT DIVERGENCE AT DAYS 4 AND 5.  THE
 TRACK FORECAST IS A BLEND OF THE FASTER CONSENSUS OF THE GLOBAL AND
 HURRICANE MODELS AND THE SLOWER PREVIOUS ADVISORY.
   
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      16/1500Z 20.2N  61.3W    75 KT
  12HR VT     17/0000Z 23.5N  59.5W    70 KT
  24HR VT     17/1200Z 28.0N  56.9W    65 KT
  36HR VT     18/0000Z 31.3N  54.3W    60 KT
  48HR VT     18/1200Z 33.4N  51.9W    55 KT
  72HR VT     19/1200Z 38.0N  45.0W    55 KT
  96HR VT     20/1200Z 40.0N  34.5W    50 KT...EXTRATROPICAL
 120HR VT     21/1200Z 40.0N  23.0W    40 KT...EXTRATROPICAL
  
 $$
 FORECASTER LANDSEA/STEWART