112 
 WTPA44 PHFO 061511
 TCDCP4
 
 TROPICAL STORM GUILLERMO DISCUSSION NUMBER  31
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP092015
 500 AM HST THU AUG 06 2015
  
 THE LOW LEVEL CIRCULATION CENTER...LLCC...OF GUILLERMO HAS BECOME 
 COMPLETELY DECOUPLED FROM ITS MID AND UPPER LEVEL CIRCULATION. THIS 
 IS DUE TO THE VERY STRONG VERTICAL WIND SHEAR AND THE ENTRAINMENT OF 
 DRIER AIR ALOFT INTO THE SYSTEM DURING THE PAST 12 TO 18 HOURS. 
 THESE CONDITIONS CONTINUE TO PRODUCE VERY HOSTILE CONDITIONS FOR THE 
 INNER CORE OF THE TROPICAL STORM. AFTER CAREFUL REANALYSIS OF THE 
 DATA REPORTED BY THE U.S. 53RD WEATHER RECONNAISSANCE SQUADRON 
 AIRCRAFT FLYING INTO GUILLERMO LAST EVENING...THIS DECOUPLING OF THE 
 LLCC HAS ALREADY BEGUN TO DISRUPT THE LOW LEVEL WINDS NEAR THE STORM 
 CENTER. EVEN THOUGH THERE WERE SFMR ESTIMATED SURFACE WINDS OF AT 
 LEAST 45 KNOTS...THESE WERE ASSOCIATED WITH THE DEEP CONVECTION... 
 WHICH WAS ABOUT 75 NM FROM THE CENTER. CLOSER TO THE STORM CENTER... 
 THE SFMR WINDS WERE APPROXIMATELY 40 KNOTS. AS A RESULT...GUILLERMO 
 IS WEAKENING MUCH FASTER THAN ANTICIPATED. THERE IS CURRENTLY A 
 SMALL CLUSTER OF ISOLATED THUNDERSTORMS WITH TOPS TO NEAR 50 
 THOUSAND FEET ABOUT 55 NM NORTH OF THE CENTER. THE SATELLITE FIX 
 AGENCIES INDICATE THAT GUILLERMO HAS WEAKENED BELOW TROPICAL STORM 
 INTENSITY...WITH JTWC AND SAB INDICATING IT WAS TOO WEAK TO 
 CLASSIFY. BASED ON ALL OF THE AVAILABLE INFORMATION FROM THE 
 AIRCRAFT AND SATELLITE BASED GUIDANCE...WE HAVE MADE GUILLERMO A 
 MINIMAL TROPICAL STORM WITH 35 KNOTS AS THE INITIAL INTENSITY. 
 
 BASED ON THE LATEST SATELLITE FIXES AND IMAGERY...THE INITIAL MOTION 
 IS JUST NORTH OF DUE WEST...OR 275 DEGREES...AT 10 KT. ONCE THE LLCC 
 BECAME DECOUPLED...IT HAS BEEN DRIVEN BY THE LOW LEVEL TRADE WIND 
 FLOW SOUTHWEST OF THE SUBTROPICAL RIDGE LOCATED FAR NORTH OF THE 
 AREA. THE FORECAST TRACK HAS BEEN ADJUSTED MORE TO THE SOUTH TO 
 ACCOUNT FOR THIS NEW STEERING MECHANISM. NOTE THAT THE TRACK IS TO 
 THE LEFT OF THE ECMWF GUIDANCE...WHICH IS THE LEFT-MOST RELIABLE 
 TRACK AVAILABLE. 
  
 WITH NO SIGNS OF DECREASING VERTICAL WIND SHEAR OR ABATEMENT OF THE
 ENTRAINMENT OF DRY AIR ALOFT...ADDITIONAL RAPID WEAKENING IS
 EXPECTED TO CONTINUE TODAY. THE INTENSITY FORECAST NOW WEAKENS
 GUILLERMO TO A TROPICAL DEPRESSION LATER THIS MORNING OR THIS
 AFTERNOON. THE DEPRESSION IS THEN FORECAST TO MAINTAIN ITSELF FOR
 THE NEXT 12 TO 36 HOURS...BUT THIS MAY BE GENEROUS GIVEN THE CURRENT
 RAPID RATE OF DECAY. IT IS POSSIBLE THAT GUILLERMO COULD BECOME A
 POST-TROPICAL/REMNANT LOW MUCH SOONER THAN ANTICIPATED...WHICH IS
 DAY 2 FOR THIS FORECAST.
 
 THE FINAL ANALYSIS OF THE WIND RADII FOUND BY THE RECONNAISSANCE
 AIRCRAFT LAST EVENING WERE USED TO MAKE ADJUSTMENTS TO THE SIZE OF
 THE STORM FOR THIS ADVISORY. NOTE THAT THERE WERE NO GALE FORCE
 WINDS IN THE SOUTHWEST QUADRANT LAST EVENING. GUILLERMO IS A VERY
 ASYMMETRIC TROPICAL CYCLONE...SO THE PRIMARY THREAT TO MARINERS
 REMAINS IN THE NORTHERN SEMICIRCLE.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  06/1500Z 21.7N 154.4W   35 KT  40 MPH
  12H  07/0000Z 22.0N 156.1W   30 KT  35 MPH
  24H  07/1200Z 22.4N 158.7W   30 KT  35 MPH
  36H  08/0000Z 22.9N 161.5W   25 KT  30 MPH
  48H  08/1200Z 23.4N 164.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
  72H  09/1200Z 24.5N 170.3W   20 KT  25 MPH...POST-TROP/REMNT LOW
  96H  10/1200Z...DISSIPATED
  
 $$
 FORECASTER HOUSTON