WTPA42 PHFO 260903
TCDCP2

TROPICAL STORM NEKI DISCUSSION NUMBER  31
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP032009
1100 PM HST SUN OCT 25 2009

THE LOW LEVEL CIRCULATION CENTER OF NEKI REMAINS TUCKED UNDER THE
WEST SIDE OF A PERSISTENT CONVECTIVE CLUSTER. THE FIX AGENCIES
REPORT A CI OF 2.5 BASED ON A SHEAR PATTERN...WITH LITTLE OR NO
CHANGE IN INTENSITY OVER THE LAST 24 HOURS. THE INITIAL INTENSITY
OF NEKI HAS BEEN LOWERED TO 35 KT IN AGREEMENT WITH THE FIX DATA.

NEKI IS LOCATED ON THE SOUTHWEST END OF A LARGE SUBTROPICAL RIDGE
AND SOUTHEAST OF AN EQUALLY LARGE AND INTENSIFYING MID-LATITUDE
LOW. OVER THE LAST 24 HOURS THE STEERING WINDS WERE LIGHT OUT OF
THE EAST-SOUTHEAST AROUND THE RIDGE AND IN THE GENERAL DIRECTION OF
THE LOW...RESULTING IN THE WEST-NORTHWEST DRIFT OF NEKI. THE
SURFACE LOW AND FRONT EXTENDING SOUTHWEST OF THE LOW...ALONG WITH A
LONGWAVE UPPER LEVEL TROUGH...HAVE MOVED TO THE EAST HOWEVER... 
PLACING NEKI IN INCREASINGLY STRONGER SOUTHERLY STEERING WINDS.

WITH THE DEEP LAYER MEAN FLOW NOW INCREASING OUT OF THE SOUTH AND
SOUTHWEST...THE VERTICAL SHEAR AS CALCULATED BY UW-CIMSS HAS
DROPPED OFF...AND IS NO LONGER A MAJOR PLAYER. THE SHEAR IS NOT
EXPECTED TO INCREASE...SO NEKI IS KEPT AT 35 KT THROUGH THE NEXT 36
HOURS. THE LARGEST 35 KT WIND RADII IS IN THE NORTHEAST QUADRANT
WHERE THERE IS A TIGHT PRESSURE GRADIENT BETWEEN NEKI AND THE
RIDGE. THE INTENSITY FORECAST IS IN THE MIDDLE OF THE ENVELOP...
CLOSEST TO GFNI AND AVNI. 

WITH NEKI UNDER THE INCREASING INFLUENCE OF THE STRENGTHENING LOW TO 
THE NORTHWEST...IT/S FORWARD MOTION SHOULD DRAMATICALLY INCREASE 
OVER THE NEXT 36 HOURS. THE TRACK FORECAST WHICH REFLECTS THIS IS IN 
THE MIDDLE OF THE OBJECTIVE AIDES...AND IS CLOSEST TO THE VARIOUS 
CONSENSUS FORECASTS. NEKI IS FORECAST TO TRANSITION INTO AN 
EXTRATROPICAL LOW AND BE ABSORBED INTO THE MID-LATITUDE LOW IN 24 TO 
36 HOURS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0900Z 25.9N 165.5W    35 KT
 12HR VT     26/1800Z 27.7N 165.3W    35 KT
 24HR VT     27/0600Z 32.0N 164.0W    35 KT...EXTRATROPICAL
 36HR VT     27/1800Z 38.5N 160.9W    35 KT...EXTRATROPICAL
 48HR VT     28/0600Z...EXTRATROPICAL
 
$$
FORECASTER CRAIG