610 
 WTPA45 PHFO 121439
 TCDCP5
 
 TROPICAL STORM HILDA DISCUSSION NUMBER  27
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP102015
 500 AM HST WED AUG 12 2015
  
 PULSING DEEP CONVECTION CONTINUES IN THE EASTERN QUADRANT OF HILDA 
 AS STRONG VERTICAL WIND SHEAR PERSISTS. DATA FROM THE LAST PASSES 
 THROUGH HILDA BY U.S. AIR FORCE WEATHER RECONNAISSANCE AIRCRAFT
 SUPPORTED AN INITIAL INTENSITY OF 40 KT. DVORAK CURRENT INTENSITY
 VALUES FROM HFO AND JTWC CAME IN AT 3.0/45 KT...AND SAB HAD A 2.5/35
 KT...WITH CIMSS ADT SUGGESTING 37 KT. A BLEND OF THESE VALUES IS IN
 LINE WITH THE RECONNAISSANCE DATA...AND GIVEN THE PULSING OF THE
 DEEP CONVECTION AND CONTINUED PARTIAL EXPOSURE OF THE LOW LEVEL 
 CIRCULATION...THE INITIAL INTENSITY IS LOWERED TO 40 KT. THE 
 RECONNAISSANCE DATA...A 0756 UTC ASCAT PASS...AND NEARBY NOAA BUOY
 51004 OBSERVATIONS WERE USED TO FINE TUNE A REDUCTION IN THE WIND
 AND SEAS RADII.
 
 HILDA IS EXPECTED TO CONTINUE WEAKENING UNDER PERSISTENT VERTICAL 
 WIND SHEAR. THE LATEST CIMSS ANALYSIS ESTIMATES THE WESTERLY WIND 
 SHEAR TO BE NEARLY 40 KT...AND THE UPPER LEVEL TROUGH PRODUCING THE 
 STRONG UPPER LEVEL WINDS RESPONSIBLE FOR THE SHEAR WILL REMAIN IN 
 PLACE FOR THE NEXT FEW DAYS. THE FORECAST FOLLOWS ICON CLOSELY AND 
 IS LESS AGGRESSIVE WITH THE WEAKENING TREND THAN SHIPS AND LGEM. 
 HILDA IS EXPECTED TO WEAKEN TO A TROPICAL DEPRESSION TONIGHT OR 
 THURSDAY AND DEGENERATE TO A REMNANT LOW BY THURSDAY NIGHT.
 
 HILDA WILL REMAIN IN A WEAK STEERING ENVIRONMENT FOR THE SHORT 
 TERM...ENSURING A SLOW MOVEMENT AS IT NEARS THE HAWAIIAN ISLANDS. 
 THE MID TO UPPER LEVEL TROUGH OVER THE REGION IS PRODUCING WESTERLY 
 WINDS ALOFT...WHILE A RATHER STRONG SURFACE HIGH FAR NORTH OF
 HAWAII IS GENERATING A SHALLOW LAYER OF EASTERLY WINDS. U.S. AIR
 FORCE WEATHER RECONNAISSANCE FOUND HILDA MAKING A SLOW DRIFT TO THE
 NORTHWEST THROUGH MUCH OF THE NIGHT...AND THE INITIAL MOTION IS
 TOWARD THE NORTHWEST...OR 305 DEGREES...AT 4 KT. THIS MOTION IS
 EXPECTED TO HOLD TODAY...FOLLOWED BY A GRADUAL TURN TOWARD THE WEST
 AND AN INCREASE IN FORWARD SPEED TONIGHT AND THURSDAY...AS HILDA
 BECOMES INCREASINGLY SHALLOW AND STEERED BY THE LOW LEVEL TRADE WIND
 FLOW. THE FORECAST TRACK CHANGED LITTLE FROM THE PAST ADVISORY AND
 RUNS ALONG THE NORTHERN EDGE OF THE GUIDANCE ENVELOPE.
 
 DUE TO UNCERTAINTY IN THE SHORT TERM...THE TROPICAL STORM WATCH
 WILL REMAIN POSTED FOR THE BIG ISLAND OF HAWAII.
  
  
  
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  12/1500Z 17.5N 152.0W   40 KT  45 MPH
  12H  13/0000Z 17.6N 152.5W   35 KT  40 MPH
  24H  13/1200Z 17.6N 153.3W   30 KT  35 MPH
  36H  14/0000Z 17.5N 154.6W   30 KT  35 MPH
  48H  14/1200Z 17.4N 156.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
  72H  15/1200Z...DISSIPATED
  
 $$
 FORECASTER WROE