138 
 WTPA44 PHFO 061455
 TCDCP4
 
 TROPICAL STORM JIMENA DISCUSSION NUMBER  44
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP132015
 500 AM HST SUN SEP 06 2015
  
 JIMENA IS EXHIBITING THE SATELLITE SIGNATURE OF A TROPICAL CYCLONE
 THAT IS FEELING THE DEBILITATING EFFECTS OF PERSISTENT AND
 RELATIVELY STRONG SOUTHWESTERLY SHEAR. INFRARED IMAGERY SHOWS CURVED
 CLOUD BANDS OF RELATIVELY WEAK CONVECTION FORMING NORTH AND EAST OF
 THE ASSUMED LOW LEVEL CIRCULATION CENTER...WHILE WATER VAPOR IMAGERY 
 SHOWS DRY AIR BEING ENTRAINED INTO THE CIRCULATION WITH THE 
 SOUTHWEST FLOW ALOFT. LATEST SUBJECTIVE CURRENT INTENSITY ESTIMATES 
 FROM PHFO/SAB/PGTW WERE 3.0/45 KT ACROSS THE BOARD...WHILE LATEST 
 UW-CIMSS ADT COMPUTATION YIELDED 3.1/47 KT. A 0730Z ASCAT PASS 
 HOWEVER INDICATED WINDS AS HIGH AS 55 KT IN THE WESTERN SEMICIRCLE. 
 AVERAGING THIS DATA SUPPORTS MAINTAINING THE INITIAL INTENSITY AT 
 50 KT FOR THIS ADVISORY.
 
 THE FORECAST TRACK PHILOSOPHY IS ESSENTIALLY UNCHANGED...AND
 THUS THE UPDATED OFFICIAL TRACK FORECAST OFFERS LITTLE CHANGE.
 JIMENA IS TRACKING NORTHWEST...325/08 KT...TOWARD A WEAKNESS IN THE
 MID-LEVEL RIDGE...BROUGHT ABOUT BY DEEP TROUGHING TO THE NORTHWEST
 OF THE MAIN HAWAIIAN ISLANDS. MID-LEVEL RIDGING CURRENTLY PREVAILS
 FROM NORTH THROUGH EAST THROUGH SOUTHEAST OF THE CYCLONE...BUT THIS
 LARGE-SCALE PATTERN IS FORECAST TO CHANGE OVER THE NEXT DAY OR TWO.
 MID-LEVEL HEIGHTS NEAR AND NORTHWEST OF HAWAII ARE EXPECTED TO
 STEADILY INCREASE AS THE CURRENT TROUGH WEAKENS AND MOVES SOUTHWEST.
 THIS ALLOWS RIDGING TO BUILD NORTH AND WEST OF JIMENA...RESULTING
 IN A TURN TOWARD THE WEST BY DAY 2 THAT IS FORECAST TO PERSIST
 THROUGH THE END OF THE FORECAST PERIOD. THE RELIABLE DYNAMICAL
 MODEL GUIDANCE ENVELOPE IS RELATIVELY SMALL THROUGH ABOUT 48
 HOURS...BUT SHOWS INCREASING SPREAD THEREAFTER DUE TO DIFFERENCES
 IN THE WAY THE MODELS HANDLE THE EVOLUTION OF THE BUILDING RIDGE. 
 THE OFFICIAL FORECAST TRACK IS VERY CLOSE TO THE GUIDANCE SUPPLIED
 BY THE GFS ENSEMBLE MEAN AND THE FLORIDA STATE SUPER ENSEMBLE.
  
 PERSISTENT WESTERLY TO NORTHWESTERLY SHEAR IS EXPECTED TO BE BETWEEN
 20 TO 30 KT THROUGH THE BULK OF THE FORECAST PERIOD...LEADING TO 
 STEADY WEAKENING...AND THE EVENTUAL DEMISE OF JIMENA. THE OFFICIAL 
 INTENSITY FORECAST MOST CLOSELY RESEMBLES LGEM GUIDANCE...AND 
 ANTICIPATES THAT JIMENA WILL BECOME A POST-TROPICAL REMNANT LOW BY 
 DAY 4. THIS IS A LITTLE LESS AGGRESSIVE IN WEAKENING JIMENA THAN 
 SHIPS GUIDANCE...WHICH ANTICIPATES DISSIPATION BY DAY 3.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  06/1500Z 24.0N 148.1W   50 KT  60 MPH
  12H  07/0000Z 25.0N 148.9W   45 KT  50 MPH
  24H  07/1200Z 25.8N 150.2W   40 KT  45 MPH
  36H  08/0000Z 26.2N 151.5W   35 KT  40 MPH
  48H  08/1200Z 26.2N 152.9W   30 KT  35 MPH
  72H  09/1200Z 26.0N 156.5W   30 KT  35 MPH
  96H  10/1200Z 26.0N 159.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 120H  11/1200Z 26.0N 162.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
  
 $$
 
 FORECASTER BIRCHARD