WTPA42 PHFO 212136 CCA TCDCP2 HURRICANE NEKI DISCUSSION NUMBER 13 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP032009 1100 AM HST WED OCT 21 2009 NEKI RAPIDLY INTENSIFIED OVERNIGHT AND INTO THE MORNING REACHING CATEGORY THREE STRENGTH. FIXES FROM PHFO...SAB...AND JTWC AT 1800 UTC WERE 5.5...WHILE CIMSS ADT CALCULATED A CI OF 6.3. GOING WITH THE FIX AGENCIES...THE INITIAL INTENSITY IS SET AT 100 KT. THE SATELLITE SIGNATURE REMAINS IMPRESSIVE...WITH OUTFLOW IN ALL QUADRANTS AND AN IMPRESSIVE OUTFLOW CHANNEL TO THE NORTH BEING PRODUCED BY AN ANTICYCLONE ALOFT JUST SOUTH OF THE MAIN HAWAIIAN ISLANDS. THE INITIAL MOTION IS TO THE NORTH-NORTHWEST...345 DEG...AT 8 KT TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE TO THE NORTH. THIS RIDGING IS BEING ERODED BY A FRONT NEAR LISIANSKI THAT IS BEING SUPPORTED BY A BROAD UPPER LEVEL TROUGH NORTH OF 27N. NEKI IS FORECAST TO CONTINUE STRENGTHENING DURING THE NEXT 24 HOURS AS THE CURRENT MOTION GRADUALLY SHIFTS TO THE NORTH. SEA SURFACE TEMPERATURES WILL REMAIN BETWEEN 27 TO 28 CELSIUS AS NEKI MOVES TOWARD THE WEAKNESS IN THE RIDGE AND THE OUTFLOW REMAINS CONDUCIVE FOR ADDITIONAL STRENGTHENING. BEYOND 24 HOURS...NEKI IS EXPECTED TO TURN TO THE NORTH-NORTHEAST AND BEGIN TO WEAKEN AS IT MOVES INTO WESTERLY VERTICAL WIND SHEAR ASSOCIATED WITH THE UPPER LEVEL TROUGH TO THE NORTH. IN ADDITION... NEKI WILL TRAVEL OVER SEA SURFACE TEMPERATURES BELOW 26 CELSIUS BY 72 HOURS...HASTENING THE WEAKENING. THE FORECAST BRINGS NEKI TO ITS PEAK INTENSITY WITHIN 24 HOURS...THEN SHOWS A STEADY WEAKENING TREND THERAFTER. THIS TREND IS IN LINE WITH THE HWRF GUIDANCE AND WEAKENS NEKI SLOWER THAN SHIPS. THE TRACK HAS BEEN NUDGED TO THE RIGHT TO BE ROUGHLY DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE... CLOSE TO THE TVCN AND JUST TO THE LEFT OF THE HWRF AND GFDL...THE TWO TOP PERFORMERS LATELY. BY 120 HOURS...THE TRACK WAS ACCELERATED TO THE NORTHEAST AS ANOTHER FRONT MOVING IN FROM THE NORTHWEST INTERACTS WITH NEKI. ON THE CURRENT TRACK...NEKI WILL BE APPROACHING THE PAPAHANAUMOKUAKEA NATIONAL MONUMENT NEAR FRENCH FRIGATE SHOALS ON FRIDAY...AND A HURRICANE WARNING HAS BEEN ISSUED FOR THE MONUMENT FROM NIHOA ISLAND TO MARO REEF. THE HURRICANE WATCH REMAINS FOR THE MONUMENT FROM MARO REEF TO LISIANSKI...AND THE TROPICAL STORM WATCH FOR JOHNSTON ISLAND HAS BEEN DISCONTINUED. LARGE SWELLS FROM THE SOUTHEAST WILL BUILD WEDNESDAY NIGHT AND CONDITIONS WILL DETERIORATE ACROSS PORTIONS OF THE WARNING AREA EARLY THURSDAY... WITH SEAS OF 15 TO 20 FT AND SURF UP 25 FT EXPECTED. FORECAST POSITIONS AND MAX WINDS INITIAL 21/2100Z 18.0N 166.8W 100 KT 12HR VT 22/0600Z 19.2N 167.0W 110 KT 24HR VT 22/1800Z 20.6N 167.3W 115 KT 36HR VT 23/0600Z 22.0N 167.5W 105 KT 48HR VT 23/1800Z 23.4N 167.5W 100 KT 72HR VT 24/1800Z 25.5N 166.8W 90 KT 96HR VT 25/1800Z 27.5N 165.8W 80 KT 120HR VT 26/1800Z 30.4N 163.8W 65 KT $$ FORECASTER WROE