486 
 WTPA43 PHFO 080909
 TCDCP3
 
 TROPICAL STORM ISELLE DISCUSSION NUMBER  33
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP092014
 1100 PM HST THU AUG 07 2014
 
 LATEST DATA FROM AN AIR FORCE RECONNAISSANCE AIRCRAFT INDICATES THAT 
 ISELLE IS NO LONGER A HURRICANE AND IS ON A WEAKENING TREND. AN 
 EYEWALL WAS NO LONGER DISCERNIBLE ON THE AIRCRAFT NOSE RADAR...WITH 
 MAXIMUM FLIGHT LEVEL WINDS NEAR 60 KT AND MAXIMUM SFMR SURFACE 
 WINDS NEAR 57 KT. ADDITIONALLY...WSR-88D DATA FROM NATIONAL WEATHER 
 SERVICE RADARS ON THE BIG ISLAND ARE DETECTING VELOCITIES NEAR 60 
 KT. BASED ON THESE DATA...THE CURRENT INTENSITY OF ISELLE IS DEEMED 
 TO BE 60 KT. 
  
 THE CURRENT MOTION ESTIMATE IS 275/09 KT...BASED ON EXTRAPOLATION 
 AND CENTER TRACKING USING WSR-88D DATA. ISELLE/S FORWARD MOTION HAS 
 SLOWED AS A WEAKNESS HAS DEVELOPED WITHIN A MID LEVEL RIDGE TO THE 
 NORTH OF THE SYSTEM...NORTHWESTERLY SHEAR HAS INCREASED TO NEAR 20 
 KT BASED ON UW-CIMSS AND SHIPS GUIDANCE...AND THE SYSTEM HAS 
 INTERACTED WITH THE TERRAIN OF THE BIG ISLAND. A MID AND UPPER 
 LEVEL LOW IS FORECAST TO DEVELOP WITHIN THIS WEAKNESS OVER THE NEXT 
 COUPLE OF DAYS...AND DROP SOUTHWARD ALONG THE FORECAST TRACK. THIS 
 WILL CAUSE THE SYSTEM TO WEAKEN TO A SHALLOW LOW THAT IS EXPECTED 
 TO TRACK MORE QUICKLY WESTWARD AS A SHALLOW LOW LATE IN THE FORECAST 
 PERIOD.
 
 ISELLE IS NOT EXPECTED TO SURVIVE THE COMBINED EFFECTS OF THE 
 INTERACTION WITH THE BIG ISLAND TERRAIN...AND THE STRONG SHEAR ALONG 
 THE FORECAST TRACK...SOME OF WHICH IS ASSOCIATED WITH THE 
 AFOREMENTIONED DEVELOPING LOW ALOFT. IF IT DOES...SHEAR IS FORECAST 
 TO RELAX LATE IN THE PERIOD AS A NEW RIDGE ALOFT BUILDS NORTH OF THE 
 FORECAST TRACK. THE INTENSITY FORECAST REMAINS ON THE LOWER END OF 
 THE GUIDANCE ENVELOPE...AND IT IS WORTH NOTING THAT SHIPS AND LGEM 
 INDICATE THAT ISELLE WILL BE ABLE TO SURVIVE THE HOSTILE SHEAR 
 BEFORE STRENGTHENING AGAIN LATE IN THE FORECAST PERIOD...WITH LGEM 
 INDICATING CLOSE TO HURRICANE INTENSITY AS ISELLE APPROACHES THE 
 DATE LINE.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  08/0900Z 19.0N 155.1W   60 KT  70 MPH
  12H  08/1800Z 19.2N 157.1W   50 KT  60 MPH
  24H  09/0600Z 19.8N 159.8W   40 KT  45 MPH
  36H  09/1800Z 20.2N 162.0W   35 KT  40 MPH
  48H  10/0600Z 20.8N 164.4W   30 KT  35 MPH
  72H  11/0600Z 22.2N 169.6W   30 KT  35 MPH
  96H  12/0600Z 24.0N 175.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 120H  13/0600Z 25.7N 177.6E   20 KT  25 MPH...POST-TROP/REMNT LOW
  
 $$
 
 FORECASTER BIRCHARD