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 WTPA42 PHFO 210311
 TCDCP2
 
 HURRICANE NEKI DISCUSSION NUMBER  10
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP032009
 500 PM HST TUE OCT 20 2009
 
 NEKI STRENGTHENED INTO A HURRICANE DURING THE DAY AS A WELL-DEFINED
 BAND OF DEEP CONVECTION WRAPPED AROUND THE LOW LEVEL CENTER AND
 FORMED A RAGGED EYE. FIXES FROM PHFO...SAB...AND JTWC ALL CAME IN
 AT A 4.0...AND CIMSS ADT CALCULATED A CI OF 4.1. THUS...THE INITIAL
 INTENSITY IS SET AT 65 KT.
  
 NEKI IS MOVING TO THE NORTHWEST...320/13...TOWARD A WEAKNESS IN THE
 SUBTROPICAL RIDGE. MID LATITUDE WEATHER SYSTEMS MOVING WITHIN A
 BROAD NORTH PACIFIC JET STREAM BETWEEN 30N AND 40N WILL CONTINUE TO
 ERODE RIDGING AT THE SURFACE AND ALOFT THAT RUNS 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 SHOWS THIS
 GENERAL TURN TO THE NORTH-NORTHWEST BUT STEADILY DIVERGES THROUGH
 TIME. THROUGH 72 HOURS...THE TRACK HAS BEEN NUDGED SLIGHTLY TO THE
 RIGHT...PUTTING IT ROUGHLY DOWN THE MIDDLE OF THE GUIDANCE CONSENSUS 
 BUT SLIGHTLY LEFT OF THE TVCN...HWRF...AND GFDL. WITH CONFIDENCE 
 BUILDING THAT NEKI WILL PASS EAST OF JOHNSTON ISLAND...THE HURRICANE 
 WATCH FOR THAT ISLAND HAS BEEN CHANGED TO A TROPICAL STORM WATCH.
  
 NEKI IS FORECAST TO CONTINUE INTENSIFYING OVER THE NEXT 48 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 SUPPORTING FURTHER INTENSIFICATION. BY 72
 HOURS...THIS OUTFLOW CHANNEL WILL BREAK DOWN AND INTENSIFICATION
 IS EXPECTED TO CEASE AS NEKI APPROACHES THE AREA OF TROUGHING
 ALOFT. THE PEAK INTENSITY OF NEKI HAS BEEN HELD BACK SLIGHTLY TO BE
 IN BETTER AGREEMENT WITH THE HWRF...WHICH SHOWS A SIMILAR INTENSITY
 TREND AS THE FORECAST.
  
 BEYOND 72 HOURS...NEKI IS FORECAST TO ENTER A REGION OF WEAK
 STEERING AND MARGINAL ATMOSPHERIC CONDITIONS WHERE THE SPREAD OF THE
 TRACK GUIDANCE BECOMES CONSIDERABLE. THE MAIN QUESTION REMAINS
 WHETHER OR NOT A SURFACE HIGH WILL BUILD TO THE NORTH AND STEER
 NEKI ON A WESTWARD TRACK. THE CONSENSUS MODELS...GFS...HRWF...AND
 GFDL ARE SUGGESTING THAT PERSISTENT SURFACE TROUGHING WILL INHIBIT
 THE DEVELOPMENT OF THE RIDGE. THUS...THE WESTWARD TURN HAS BEEN
 ELIMINATED IN FAVOR OF A SLOW NORTHWARD MOTION AND GRADUAL 
 WEAKENING. 
 
 IT IS IMPORTANT TO NOTE THAT DURING THE WEEKEND NEKI IS FORECAST TO 
 BE CLOSE TO THE EASTERN PORTION OF THE PAPAHANAUMOKUAKEA NATIONAL 
 MONUMENT BETWEEN FRENCH FRIGATE SHOALS AND LAYSAN ISLAND. 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      21/0300Z 15.5N 165.2W    65 KT
  12HR VT     21/1200Z 16.8N 166.3W    75 KT
  24HR VT     22/0000Z 18.2N 167.2W    80 KT
  36HR VT     22/1200Z 19.3N 167.7W    90 KT
  48HR VT     23/0000Z 20.4N 168.3W    95 KT
  72HR VT     24/0000Z 22.2N 169.3W    95 KT
  96HR VT     25/0000Z 23.6N 170.3W    90 KT
 120HR VT     26/0000Z 25.1N 171.0W    80 KT
  
 $$
 FORECASTER WROE