WTPA42 PHFO 242052
TCDCP2

TROPICAL STORM NEKI DISCUSSION NUMBER  25
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP032009
1100 AM HST SAT OCT 24 2009

TROPICAL STORM NEKI CONTINUES TO BE IMPACTED BY SOUTHWESTERLY SHEAR
THIS MORNING WITH INFRARED AND MICROWAVE DATA SHOWING DEEP
CONVECTION DISPLACED SLIGHTLY TO THE NORTHEAST OF THE SYSTEM/S
CENTER. CIMSS ANALYSIS DATA FROM 1800 UTC SHOWED OVER 26 KT OF
VERTICAL SHEAR FROM THE SOUTHWEST. DVORAK DATA FROM PHFO...SAB AND
JTWC ALL INDICATED AN INTENSITY OF 45 KT. HOWEVER...A SCATTEROMETER
PASS FROM AROUND 1640 UTC SHOWED UNFLAGGED 50 KT WINDS SOUTHEAST OF
THE CENTER. GIVEN THE RECENT SCATTEROMETER DATA AND THE RELATIVELY
STEADY STATE PRESENTATION IN THE GOES SATELLITE DATA...THE INITIAL
INTENSITY WILL BE KEPT AT 50 KT FOR THIS FORECAST PACKAGE. 
 
NEKI IS MOVING IN A WEAK STEERING CURRENT WITH A WEAK MIDLEVEL RIDGE
TO THE SOUTHEAST OVER THE MAIN HAWAIIAN ISLANDS AND A TROUGH FAR TO 
THE NORTH. LITTLE CHANGE IS EXPECTED OVER THE NEXT 36 TO 48
HOURS...AFTER WHICH A SHORTWAVE TROUGH WILL MOVE IN FROM THE WEST
AND ABSORB NEKI. THE MAIN DYNAMICAL MODELS SHOW MORE OF A NORTHWARD
TRACK THAN PREVIOUSLY INDICATED SO THE FORECAST HAS BEEN NUDGED A
BIT TO THE WEST ACCORDINGLY. RECENT SATELLITE IMAGES ALSO SUPPORT
THIS TREND.

THE CENTER OF NEKI IS CURRENTLY OVER MARGINAL SEA SURFACE
TEMPERATURES AND THE VERTICAL SHEAR IS NOT EXPECTED TO EASE
SIGNIFICANTLY.  THUS...NEKI IS FORECAST TO WEAKEN SLOWLY OVER THE
NEXT COUPLE OF DAYS...FOLLOWED BY A TRANSITION TO AN EXTRATROPICAL
STATE AS THE PREVIOUSLY MENTIONED SHORTWAVE TROUGH EXERTS ITS
INFLUENCE.
 
THE LATEST BUOY AND SCATTEROMETER DATA WARRANT KEEPING THE TROPICAL
STORM WARNING UP FOR THE PAPAHANAUMOKUAKEA NATIONAL MONUMENT FOR
THIS FORECAST PACKAGE.  CONDITIONS SHOULD IMPROVE AS NEKI MOVES
AWAY FROM THE AREA AND THE WARNING MAY BE DROPPED LATER TODAY
PENDING THE RESULTS OF FURTHER DATA ANALYSIS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/2100Z 24.8N 163.9W    50 KT
 12HR VT     25/0600Z 25.6N 163.7W    45 KT
 24HR VT     25/1800Z 26.6N 163.7W    45 KT
 36HR VT     26/0600Z 27.8N 163.9W    40 KT
 48HR VT     26/1800Z 30.4N 163.9W    35 KT...BECOMING EXTRATROPICAL
 72HR VT     27/1800Z 39.6N 159.3W    35 KT...EXTRATROPICAL
 
$$
FORECASTER KODAMA