WTPA42 PHFO 211448
TCDCP2

HURRICANE NEKI DISCUSSION NUMBER  12
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP032009
500 AM HST WED OCT 21 2009

SATELLITE IMAGERY SHOWED AN IMPRESSIVE INCREASE IN ORGANIZATION FOR
HURRICANE NEKI OVERNIGHT. FIXES FROM PHFO...JTWC AND SAB AT 1200
UTC WERE 4.5...4.5 AND 5.0. THE HURRICANE LOOKED EVEN MORE
IMPRESSIVE JUST AFTER 1200 UTC. WE SET THE INITIAL INTENSITY AT 90
KT. A QUIKSCAT PASS LAST EVENING SHOWED A VERY ASYMMETRIC WIND FIELD
WITH 35 KT WINDS EXTENDING MUCH FARTHER OUT ON THE NORTHEAST AND
SOUTHEAST SIDES OF THE STORM. A TIGHT PRESSURE GRADIENT CONTINUES
BETWEEN NEKI AND A HIGH TO THE NORTHEAST...SO WE HAVE KEPT THE
ASYMMETRIC WIND FIELD IN OUR FORECAST.
 
OVER THE PAST SEVERAL HOURS NEKI HAS SLOWED ITS FORWARD MOTION AND
TAKEN A TURN TOWARD THE NORTH-NORTHWEST. THIS WAS EXPECTED AS A
TROUGH ALOFT IS MOVING BY TO THE NORTH. NEKI IS EXPECTED TO
GRADUALLY CURVE TOWARD THE NORTH AND EVENTUALLY TOWARD THE NORTH
NORTHEAST. THE TRACK GUIDANCE IS NOW A BIT MORE CONSISTENT THAN 6
HOURS AGO WITH MOST MODELS SHOWING NEKI GRADUALLY RECURVING. WE
HAVE ADJUSTED THE FORECAST TRACK FARTHER A BIT FARTHER TO THE 
RIGHT OF OUR PREVIOUS TRACK.
 
NEKI IS FORECAST TO CONTINUE INTENSIFYING OVER THE NEXT 48 HOURS.
SST VALUES WILL REMAIN IN THE 27 TO 28 DEGREE RANGE WITH LITTLE
VERTICAL WIND SHEAR FOR THE NEXT 36 HOURS. AFTER 36 HOURS...WEST TO
NORTHWEST SHEAR WILL INCREASE AND WATER TEMPERATURES WILL COOL.
THOSE CHANGES WILL CAUSE NEKI TO STEADILY WEAKEN AFTER 48 HOURS.
 
THE FORECAST TRACK SHOULD KEEP NEKI FAR ENOUGH NORTHEAST OF JOHNSTON
ISLAND TO KEEP TROPICAL STORM FORCE WINDS FROM REACHING THE ISLAND
BUT THERE IS ENOUGH UNCERTAINTY IN THE TRACK TO WARRANT KEEPING THE
TROPICAL STORM WATCH IN EFFECT FOR JOHNSTON. OUR FORECAST TRACK HAS
NEKI MOVING THROUGH THE PAPAHANAUMOKUAKEA NATIONAL MONUMENT BETWEEN
FRENCH FRIGATE SHOALS AND LISIANSKI ISLAND IN 72 HOURS. LARGE
SWELLS FROM THE SOUTHEAST MAY REACH THE MONUMENT AS EARLY AS
THURSDAY. A HURRICANE WATCH MAY BE NEEDED FOR PAPAHANAUMOKUAKEA AS
EARLY AS TONIGHT.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/1500Z 17.0N 166.6W    90 KT
 12HR VT     22/0000Z 18.2N 167.3W    95 KT
 24HR VT     22/1200Z 19.8N 167.9W    95 KT
 36HR VT     23/0000Z 21.2N 168.2W   105 KT
 48HR VT     23/1200Z 22.4N 168.3W   110 KT
 72HR VT     24/1200Z 24.6N 168.5W   100 KT
 96HR VT     25/1200Z 27.5N 168.5W    90 KT
120HR VT     26/1200Z 30.0N 167.5W    80 KT
 
$$
FORECASTER DONALDSON