Yellow Evan wrote:CPHC still yet to release a discussion.
HURRICANE ISELLE DISCUSSION NUMBER 31
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
1100 AM HST THU AUG 07 2014
ISELLE CONTINUES TO GRADUALLY WEAKEN. THE EYE IS NO LONGER EVIDENT
IN SATELLITE IMAGERY...AND THE RECONNASIANCE AIRCRAFT FOUND THE
SURFACE PRESSURE AT THE CENTER HAD RISEN A COUPLE OF MILLIBARS.
MAXIMUM FLIGHT LEVEL WINDS ON THE NORTHEAST SIDE OF THE CYCLONE WERE
69 KT...WHICH SUGGESTS MAXIMUM SURFACE WINDS NEAR 60 KT. OTHER
REDUCTION FACTOR TECHNIQUES WERE SUGGESTING 60 TO 65 KT MAXIMUM
SUSTAINED SURFACE WINDS. THUS THE INTENSITY FOR THIS ADVISORY IS
BEING LOWERED TO 65 KNOTS...AND THIS COULD BE A LITTLE GENEROUS.
ISELLE IS STILL LOCATED IN A REGION OF RELATIVELY WEAK SHEAR BETWEEN
TWO UPPER LEVEL ANTICYCLONES...TO ITS EAST AND WEST. THE HURRICANE
HAS BEEN MOVING SLIGHTLY FASTER THAN THIS WEAKNESS...AND WILL START
TO FEEL INCREASING NORTHERLY SHEAR OVER THE NEXT 12 HOURS WHICH WILL
MAINTAIN A WEAKENING TREND DESPITE GRADUALLY INCREASING SEA SURFACE
TEMPERATURES. EVEN IF ISELLE REACHES THE BIG ISLAND AS A TROPICAL
STORM...SIGNIFICANT IMPACTS WILL STILL BE FELT FROM WIND...RAIN...
AND SURF.
BEYOND 12 HOURS...THE COMBINATION OF MUCH STRONGER NORTHERLY SHEAR
AND INTERACTION WITH THE BIG ISLAND TERRAIN IS EXPECTED TO WEAKEN
ISELLE FURTHER. THE TRACK GUIDANCE SHOWED A LITTLE MORE SPREAD FOR
THIS CYCLE...AND SHIFTED SOMEWHAT TO THE SOUTH BEYOND 24 HOURS...
LIKELY DUE TO UNCERTAINTIES WITH THE INTENSITY OF A WEAKER ISELLE.
THE OFFICIAL FORECAST THUS FOLLOWS A SIMILAR TREND WITH A SLIGHT
SOUTHWARD SHIFT BEYOND 24 HOURS. THE INTENSITY FORECAST IS LOWER
THAN THE CONSENSUS BEYOND 72 HOURS WHEN ISELLE IS EXPECTED TO
INTERACT WITH AN UPPER LEVEL LOW DIGGING SOUTH OVER THE NORTHWEST
HAWAIIAN ISLANDS. THERE IS A GOOD CHANCE ISELLE WILL NOT SURVIVE THE
INTERACTION WITH THIS UPPER TROUGH.
FORECAST POSITIONS AND MAX WINDS
INIT 07/2100Z 18.9N 152.2W 65 KT 75 MPH
12H 08/0600Z 19.4N 154.5W 60 KT 70 MPH
24H 08/1800Z 19.9N 157.4W 55 KT 65 MPH
36H 09/0600Z 20.4N 160.0W 45 KT 50 MPH
48H 09/1800Z 20.9N 162.2W 40 KT 45 MPH
72H 10/1800Z 21.8N 166.2W 35 KT 40 MPH
96H 11/1800Z 23.7N 172.0W 30 KT 35 MPH
120H 12/1800Z 25.9N 178.5W 25 KT 30 MPH...POST-TROP/REMNT LOW