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 413 
 WTPA44 PHFO 050857
 TCDCP4
 
 TROPICAL STORM GUILLERMO DISCUSSION NUMBER  26
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP092015
 1100 PM HST TUE AUG 04 2015
  
 WE ONCE AGAIN HAVE THE LUXURY OF REAL-TIME IN SITU OBSERVATIONS OF 
 GUILLERMO...PROVIDED BY US AIR FORCE HURRICANE HUNTERS. THE LATEST 
 AIRCRAFT DATA...AS WELL AS SATELLITE OBSERVATIONS...INDICATE THAT 
 GUILLERMO IS BEGINNING TO WEAKEN...WITH MAXIMUM SUSTAINED SURFACE 
 WINDS ESTIMATED TO BE 55 KT BASED ON SFMR AND FLIGHT LEVEL WINDS. 
 
 WHILE WATER TEMPERATURES ALONG THE FORECAST TRACK ARE SUFFICIENTLY 
 WARM TO SUPPORT A STRONG HURRICANE...PERSISTENT STRONG VERTICAL 
 SHEAR WILL PRECLUDE THAT FROM OCCURRING. THE CYCLONE HAS MOVED NORTH 
 OF A RIDGE AXIS ALOFT...AND IS NOW ENCOUNTERING STRONG WESTERLY 
 WINDS ALOFT...ASSOCIATED WITH THE SUBTROPICAL JET. THE INITIAL 
 MOTION VECTOR IS ESTIMATED TO BE 295/07 KT...WITH THE RECENT SLOWING 
 AND WESTWARD TURN LIKELY RELATED TO THE SYSTEM BECOMING INCREASINGLY 
 DECOUPLED IN THE PRESENCE OF THE STRONG SHEAR...ANALYZED AS BEING AS 
 HIGH AS 35 KT. WITH EVEN GREATER SHEAR VALUES ALONG THE FORECAST 
 TRACK...A STEADY WEAKENING TREND IS ANTICIPATED UNTIL DISSIPATION 
 OCCURS BY DAY 5. SHIPS GUIDANCE DISSIPATES THE SYSTEM WITHIN 72 
 HOURS...AND THE LATEST ECMWF GUIDANCE OFFERED A DRAMATIC CHANGE FROM 
 PREVIOUS RUNS...WITH GUILLERMO NOW DEPICTED AS WEAKENING TO AN OPEN 
 WAVE WITHIN 48 HOURS. THE LATEST INTENSITY FORECAST IS SIMILAR TO 
 THE PREVIOUS...BUT HAS ACCELERATED THE WEAKENING TREND...AND CLOSELY 
 FOLLOWS THE IVCN. 
 
 AS FAR AS THE TRACK FORECAST...THE MUCH WEAKER SYSTEM ASSUMES A 
 NEARLY DUE WEST TRACK IN THE LATEST ECMWF GUIDANCE...STEERED BY THE 
 LOW LEVEL TRADE WIND FLOW...AND THUS THE TVCN AND GFEX CONSENSUS 
 GUIDANCE HAS SHIFTED SOUTHWARD AGAIN...CONTINUING A TREND THAT BEGAN 
 ABOUT 12 HOURS AGO. THE UPDATED TRACK FORECAST PARALLELS THE 
 PREVIOUS...BUT HAS BEEN SHIFTED SLIGHTLY SOUTHWARD...AND CLOSELY 
 MIRRORS THE GFEX. ALTHOUGH THE PROBABILITY OF SUSTAINED TROPICAL 
 STORM FORCE WINDS IN THE WATCH AREA HAVE DIMINISHED SLIGHTLY WITH 
 THIS ADVISORY...NO CHANGES WILL BE MADE TO THE WATCH AT THIS TIME. 
 12 FOOT SEA RADII WERE EXPANDED IN MOST QUADRANTS DUE TO 
 OBSERVATIONS FROM NOAA BUOY 51004...WHICH INDICATED THAT CURRENT 
 WAVE WATCH GUIDANCE WAS UNDERDONE IN THE SOUTHWEST QUADRANT. 
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  05/0900Z 20.6N 150.3W   55 KT  65 MPH
  12H  05/1800Z 21.0N 151.7W   50 KT  60 MPH
  24H  06/0600Z 21.9N 153.7W   45 KT  50 MPH
  36H  06/1800Z 22.5N 155.6W   40 KT  45 MPH
  48H  07/0600Z 23.0N 158.0W   35 KT  40 MPH
  72H  08/0600Z 24.0N 162.0W   30 KT  35 MPH
  96H  09/0600Z 26.0N 167.0W   25 KT  30 MPH...POST-TROPICAL
 120H  10/0600Z...DISSIPATED
  
 $$
 
 FORECASTER BIRCHARD
 
 
 
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