WTPA42 PHFO 202109
TCDCP2

TROPICAL STORM NEKI DISCUSSION NUMBER   9
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP032009
1100 AM HST TUE OCT 20 2009

NEKI CONTINUES TO STEADILY INTENSIFY. A WELL DEFINED CONVECTIVE BAND
IS BEGINNING TO WRAP AROUND THE LOW LEVEL CIRCULATION CENTER...WITH
THE RECENT FIXES COMING IN AT 3.5 FROM CPHC AND SAB...4.0 FROM
JTWC...AND 3.7 FROM CIMSS ADT. BASED ON AN AVERAGE OF THESE DATA...
THE INITIAL INTENSITY IS SET AT 60 KT.

NEKI IS MOVING TO THE NORTHWEST TOWARD A WEAKNESS IN THE SUBTROPICAL
RIDGE. TROUGHS MOVING WITHIN A BROAD NORTH PACIFIC JET STREAM
BETWEEN 30N AND 40N WILL CONTINUE TO ERODE RIDGING AT THE SURFACE
AND ALOFT RUNNING ROUGHLY ALONG 25N TO THE NORTH OF NEKI. AS A
RESULT...NEKI WILL GRADUALLY TURN TO THE NORTH-NORTHWEST OVER THE
NEXT 72 HOURS. THE GUIDANCE IS TIGHTLY CLUSTERED ON THIS SCENARIO
BUT SLIGHTLY TO THE RIGHT OF THE PREVIOUS FORECAST. THUS...THE
TRACK HAS BEEN NUDGED SLIGHTLY TO THE RIGHT AND FOLLOWS CLOSELY THE
TVCN AND RECENTLY WELL-PERFORMING HWRF AND GFDL. THIS TRACK KEEPS
NEKI WELL SOUTHWEST OF THE MAIN HAWAIIAN ISLANDS BUT BRINGS IT
CLOSE ENOUGH TO JOHNSTON ISLAND TO WARRANT THE CONTINUATION OF THE
HURRICANE WATCH FOR THAT ISLAND.

NEKI IS FORECAST TO CONTINUE INTENSIFYING OVER THE NEXT 72 HOURS.
SST VALUES WILL REMAIN IN THE 27 TO 28 DEGREE RANGE WITH LITTLE
VERTICAL WIND SHEAR. AN ANTICYCLONE SITTING OVER THE MAIN HAWAIIAN
ISLANDS AND THE BROAD UPPER TROUGHING TO NORTH WILL CONTINUE TO
PROVIDE AN OUTFLOW CHANNEL SUPPORT FURTHER INTENSIFICATION.
 
BEYOND 72 HOURS...NEKI IS FORECAST TO ENTER A REGION OF WEAK
STEERING AND INCREASINGLY HOSTILE CONDITIONS. THE SPREAD OF THE
TRACK GUIDANCE BECOMES CONSIDERABLE AS NEKI WILL BE VERY CLOSE TO
THE COL REGION BETWEEN DEEP TROUGHING TO THE NORTH AND RIDGING TO
THE EAST AND WEST. AS A RESULT...THE TURN TO THE WEST HAS BEEN
DELAYED...CAUSING A SHIFT TO THE RIGHT IN THE TRACK TO BE CLOSE TO
THE TVCN AND BETWEEN THE GFDL AND HWRF SOLUTIONS. A SLOW WEAKENING
IS IN THE FORECAST AS VERTICAL WIND SHEAR MAY COME INTO PLAY. IT IS
IMPORTANT TO NOTE THAT THE TRACK WILL BE CLOSE TO THE EASTERN
PORTION OF THE PAPAHANAUMOKUAKEA NATIONAL MONUMENT NEAR FRENCH
FRIGATE SHOALS AND MARO REEF. LARGE SWELLS FROM THE SOUTHEAST CAN
BE EXPECTED OVER THE SMALL ISLANDS AND SHOALS WITHIN THE MONUMENT
AS EARLY AS THURSDAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/2100Z 14.4N 164.0W    60 KT
 12HR VT     21/0600Z 15.8N 165.3W    65 KT
 24HR VT     21/1800Z 17.4N 166.6W    75 KT
 36HR VT     22/0600Z 18.6N 167.3W    85 KT
 48HR VT     22/1800Z 19.6N 167.9W    95 KT
 72HR VT     23/1800Z 21.4N 168.8W   100 KT
 96HR VT     24/1800Z 22.9N 169.8W    95 KT
120HR VT     25/1800Z 23.9N 171.4W    85 KT
 
$$
FORECASTER WROE