WTPA42 PHFO 220913 TCDCP2 HURRICANE NEKI DISCUSSION NUMBER 15 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP032009 1100 PM HST WED OCT 21 2009 HURRICANE NEKI HAS LIKELY REACHED PEAK INTENSITY THIS EVENING. FIXES FROM PHFO AND JTWC REPORT CI OF 5.5 WHILE SAB REPORTS 6.0...UNCHANGED FROM 6 HOURS AGO. PHFO ALSO REPORTS STEADY FOR A 24 HOUR TREND INSTEAD OF DEVELOPING...A FIRST FOR THIS SYSTEM. THE INITIAL INTENSITY IS THEREFORE SET AT 105 KT AS A NOD TO CONTINUITY FROM 6 HOURS AGO. OUTFLOW REMAINS GOOD...IF A BIT ASYMMETRIC. SOUTHWEST SHEAR IS EVIDENT...WITH THE 0600 UTC UW-CIMSS VERTICAL SHEAR PRODUCT SHOWING 18 TO 20 KT OF SHEAR. THIS APPEARS TO BE JUST ENOUGH SHEAR TO AFFECT THE CORE...WHICH PRESENTS AS A CLOUDED EYE AT THIS HOUR. NEKI REMAINS OVER 28 DEGREE C WATER...BUT LITTLE OR NO STRENGTHENING IS EXPECTED. NEKI APPEARS TO HAVE REACHED THE WESTERNMOST POINT OF ITS TRACK...WITH A SLIGHT EAST COMPONENT NOTED IN LAST 6 HOUR MOTION. INITIAL MOTION IS SET AT 010 DEGREES AT 10 KT. A FRONT MOVING SOUTHEASTWARD NEAR LISIANSKI IS ERODING THE SUBTROPICAL RIDGE...URGING NEKI EVER NORTHWARD. NEKI IS EXPECTED TO GRADUALLY SHIFT TO A MORE NORTHEASTERLY TRACK AS IT INTERACTS WITH THE ENCROACHING FRONT AND ITS ASSOCIATED UPPER LEVEL TROUGH. THE FORECAST TRACK IS SLIGHTLY TO THE RIGHT OF THE PREVIOUS ONE...JUST WITHIN THE RIGHT SIDE OF THE GUIDANCE ENVELOPE AND ALONG HWRF...WHICH SEEMS TO HAVE PERFORMED QUITE WELL WITH THIS SYSTEM. NEKI WILL REMAIN IN 26 C OR WARMER WATER THROUGH 48 HOURS...THEN MOVE ACROSS COOLER WATER THROUGH THE REST OF ITS FORECAST TRACK. UW-CIMSS SHOWS NEUTRAL SHEAR IMPACT ON THIS SYSTEM THROUGH 24 HOURS...SO NO WEAKENING IS FORECAST THROUGH TONIGHT. GRADUAL WEAKENING IS INTRODUCED AT 24 HOURS...WITH CONTINUED WEAKENING EXPECTED AFTERWARD. NEKI IS FORECAST TO BE A TROPICAL STORM AFTER 72 HOURS...THEN A DEPRESSION AT 120 HOURS. THE LONG RANGE INTENSITY FORECAST MAY CHANGE DEPENDING ON HOW NEKI INTERACTS WITH THE FRONT AND UPPER TROUGH. ON THE CURRENT TRACK...NEKI WILL BE APPROACHING THE PAPAHANAUMOKUAKEA NATIONAL MONUMENT NEAR FRENCH FRIGATE SHOALS ON FRIDAY...AND A HURRICANE WARNING REMAINS FOR THE MONUMENT FROM NIHOA ISLAND TO MARO REEF. A TROPICAL STORM WATCH REMAINS IN EFFECT FROM MARO REEF TO LISIANSKI...BUT THIS WILL LIKELY BE DROPPED WITH THE NEXT BULLETIN IF THE EASTERLY COMPONENT WITHIN THE TRACK INCREASES. LARGE SWELLS FROM THE SOUTH WILL BUILD TONIGHT AND CONDITIONS WILL DETERIORATE ACROSS PORTIONS OF THE WARNING AREA THURSDAY...WITH SEAS GREATER THAN 20 FT AND SURF UP 25 FT EXPECTED. FORECAST POSITIONS AND MAX WINDS INITIAL 22/0900Z 19.7N 166.5W 105 KT 12HR VT 22/1800Z 21.0N 166.2W 105 KT 24HR VT 23/0600Z 22.7N 165.8W 100 KT 36HR VT 23/1800Z 24.3N 165.1W 90 KT 48HR VT 24/0600Z 25.8N 164.2W 80 KT 72HR VT 25/0600Z 28.7N 162.0W 65 KT 96HR VT 26/0600Z 31.8N 159.7W 50 KT 120HR VT 27/0600Z 35.6N 157.2W 30 KT $$ FORECASTER POWELL