WTPA42 PHFO 232100 TCDCP2 TROPICAL STORM NEKI DISCUSSION NUMBER 21 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP032009 1100 AM HST FRI OCT 23 2009 SATELLITE IMAGERY SHOWS THAT NEKI CONTINUES TO DETERIORATE THIS MORNING. VISIBLE IMAGES ARE NOW REVEALING A PARTIALLY EXPOSED LLCC. THE LAYERED CLOUDS AND WHAT REMAINS OF THE DEEP CONVECTION HAVE BEEN PUSHED TO THE NORTHEAST OF THE CENTER BY 25 TO 30 KT OF SOUTHWESTERLY SHEAR...AS ANALYZED IN THE UW/CIMSS SHEAR ANALYSIS. CURRENT INTENSITY ESTIMATES FROM PHFO...JTWC...AND SAB WERE A CONSENSUS 3.5 AND SO THE INTENSITY ESTIMATE WAS SET TO 55 KT FOR THIS ADVISORY. THE INITIAL MOTION ESTIMATE IS 025/4. NEKI IS LOCATED IN A COL BETWEEN SUBTROPICAL HIGH PRESSURE CENTERS TO THE EAST AND WEST... THE LOWER EQUATORIAL PRESSURE TO THE SOUTH...AND A SERIES OF EXTRATROPICAL LOW PRESSURE CENTERS PASSING BY TO THE NORTH. THE MID-LATITUDE SHORTWAVE TROUGHS PASSING BY TO THE NORTH OF NEKI WILL LEAVE THE CYCLONE BEHIND...WITH HIGH PRESSURE BUILDING TO THE NORTH THROUGH 36 TO 48 HOURS. THIS WILL KEEP NEKI IN RELATIVELY WEAK STEERING CURRENTS. BEYOND 48 HOURS...A MUCH STRONGER MID-LATITUDE TROUGH IS EXPECTED TO SWEEP NEKI INTO THE WESTERLIES. THERE IS SOME DISAGREEMENT ABOUT THE EVOLUTION OF WHAT IS LEFT OF NEKI AFTER THAT...WHETHER THE CYCLONE BEGINS TO MERGE WITH EXTRATROPICAL LOW PRESSURE...OR WHETHER THE LOW LEVEL CENTER BECOMES BECOMES ELONGATED AND TORN APART. THE OFFICIAL FORECAST IS CLOSE TO...BUT SOMEWHAT SLOWER THAN THE PREVIOUS FORECAST IN THE SHORT TERM...WITH A SLIGHT ADJUSTMENT TO THE LEFT IN THE LONGER TERM. STRONG SOUTHWEST SHEAR IS EXPECTED TO CONTINUE OVER THE CYCLONE THROUGH AT LEAST THE NEXT 48 HOURS. SOME OF THE GLOBAL MODELS SUGGEST THAT SHEAR WILL WEAKEN BEYOND 48 HOURS...BUT BY THEN NEKI WILL BE APPROACHING THE MUCH COLDER WATERS OF THE NORTH PACIFIC. AGAIN...IT IS UNCERTAIN HOW MUCH BAROCLINIC ENHANCEMENT NEKI COULD GET IN THE LONGER RANGE. LITTLE CHANGE TO THE INTENSITY FORECAST WAS MADE THROUGH 36 HOURS...WITH A SLIGHTLY SLOWER WEAKENING TREND INDICATED FOR 48 HOURS AND BEYOND. THE CLOSEST AVAILABLE OBSERVATION...FROM BUOY 51001...INDICATED WINDS GUSTING TO 35 KT AT 1750 UTC. BASED ON THIS...AND MORE IMPORTANTLY ON THE VERY TIMELY QUIKSCAT WIND PASS FROM 1705 UTC... WE HAVE MADE SOME ADJUSTMENTS TO THE WIND RADII. NEKI/S RELATIVELY CLOSE APPROACH TO THE MAIN HAWAIIAN ISLANDS IS A SOBERING REMINDER THAT WE STILL HAVE MORE THAN A MONTH TO GO IN HURRICANE SEASON. FORECAST POSITIONS AND MAX WINDS INITIAL 23/2100Z 23.1N 165.3W 55 KT 12HR VT 24/0600Z 23.7N 165.1W 50 KT 24HR VT 24/1800Z 24.8N 164.6W 45 KT 36HR VT 25/0600Z 25.8N 164.0W 40 KT 48HR VT 25/1800Z 27.1N 163.2W 35 KT 72HR VT 26/1800Z 30.6N 161.1W 30 KT...DISSIPATING 96HR VT 27/1800Z 36.9N 157.4W 25 KT...EXTRATROPICAL $$ FORECASTER R BALLARD