520 
 WTPA45 PHFO 260900
 TCDCP5
 
 TROPICAL STORM HILDA DISCUSSION NUMBER  16
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP112009
 1100 PM HST TUE AUG 25 2009
 
 HILDA...IN SPITE OF MINIMAL SHEAR AND WARM SST/S...IS BARELY HANGING 
 ON. THE POSSIBLE REASON FOR THE ONGOING STRUGGLE IS THE INTAKE OF
 DRY MID-LEVEL AIR THAT SURROUNDS HILDA TO THE NORTH...AS DEPICTED
 BY WATER VAPOR SATELLITE IMAGERY. THE FIX AGENCIES AND AN ADT ALL
 REPORT A 24 HOUR WEAKENING TREND WITH SUBJECTIVE DVORAK ESTIMATES
 RANGING FROM 35 TO 55 KT...THE LATTER KEPT HIGH DUE TO DVORAK
 CONSTRAINTS. DEEP CONVECTION HAS PERSISTED NEAR THE STORM CENTER
 OVER THE LAST SEVERAL HOURS...SO RATHER THAN DROPPING THE INTENSITY
 WITH THIS FORECAST...WILL KEEP IT AT 40 KT.
 
 HILDA CONTINUES TO MOVE TO THE WEST-SOUTHWEST...THE RESULT OF 
 NORTHEASTERLY WINDS FLOWING AROUND A HIGH CENTERED NORTHWEST OF
 HAWAII. THERE IS GOOD AGREEMENT AMONGST THE OBJECTIVE AIDS THAT
 HILDA WILL REMAIN ON THIS COURSE FOR 24 HOURS WHILST UNDER THE
 INFLUENCE OF THE HIGH TO ITS NORTHWEST. BEYOND 24 HOURS...GLOBAL
 MODELS RETREAT THE HIGH TO THE NORTH...ALLOWING HILDA TO ASSUME A
 WESTERLY COURSE THROUGH 48 HOURS THEN A WEST-NORTHWESTERLY TRACK
 THEREAFTER. MOST OF THE OBJECTIVE AIDES INDICATE TO A DEGREE THAT
 THIS WILL OCCUR. THE OFFICIAL FORECAST IS DOWN THE MIDDLE OF A
 SOMEWHAT TIGHT AID ENVELOP AND IS CLOSEST TO CONSENSUS TVCN AND THE
 REGIONAL HWRF MODEL.
 
 THE INTENSITY FORECAST REMAINS A WORK IN PROGRESS. IT MAINTAINS THE
 SLOW WEAKENING TREND THROUGH 12 HOURS...FOLLOWED BY AN EQUALLY SLOW
 STRENGTHENING TREND THROUGH 72 HOURS. BEYOND 72 HOURS... INCREASING
 VERTICAL SHEAR IS EXPECTED TO SLOWLY WEAKEN HILDA. ABOUT HALF OF
 THE INTENSITY AIDS MAINTAIN OR SLOWLY WEAKEN HILDA...WHILE THE
 OTHER HALF SLOWLY STRENGTHEN THE CYCLONE. ALL OF THE AIDS AS DOES
 THE OFFICIAL FORECAST KEEP HILDA BELOW THE 65 KNOT HURRICANE
 THRESHOLD. THE OFFICIAL FORECAST FOLLOWS LGEM THROUGH 72 HOURS THEN
 ENDS UP NEAR HWRF ICON AND IVCN AT 120 HOURS. 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      26/0900Z 13.6N 150.6W    40 KT
  12HR VT     26/1800Z 13.2N 151.7W    35 KT
  24HR VT     27/0600Z 12.8N 153.2W    40 KT
  36HR VT     27/1800Z 12.7N 154.8W    45 KT
  48HR VT     28/0600Z 12.8N 156.7W    45 KT
  72HR VT     29/0600Z 13.5N 161.3W    50 KT
  96HR VT     30/0600Z 14.5N 165.7W    50 KT
 120HR VT     31/0600Z 16.3N 170.0W    45 KT
  
 $$
 FORECASTER CRAIG