000 WTPA41 PHFO 310255 TCDCP1 TROPICAL STORM LANA DISCUSSION NUMBER 3 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP062009 ISSUED BY NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 500 PM HST THU JUL 30 2009 LANA HAS CONTINUED TO INTENSIFY THIS AFTERNOON WITH A WELL-DEFINED SPIRAL BAND PATTERN PRESENT ON SATELLITE IMAGERY. IN ADDITION... AN AQUA MICROWAVE PASS AT 2240 UTC SHOWS SIGNIFICANT INNER-CORE STRUCTURE WITH A BROKEN RING OF CONVECTION AROUND THE STORM CENTER. DVORAK ESTIMATES AT 0000 UTC WERE 45 KT FROM TAFB/CIMSS...AND SINCE THAT TIME...THE CYCLONE IS BECOMING BETTER-ORGANIZED WITH INCREASING CONVECTION ON THE WESTERN SIDE. THE INITIAL INTENSITY IS RAISED TO 50 KT...AND THIS COULD BE CONSERVATIVE BASED ON THE MICROWAVE AND RECENT INFRARED SATELLITE DATA. VERTICAL WIND SHEAR IS EXPECTED TO BE LOW FOR THE NEXT DAY OR SO AS LANA REMAINS UNDER THE INFLUENCE OF THE SOUTHWESTERN PORTION OF AN UPPER HIGH. THIS LIGHT SHEAR ALONG WITH WARM SSTS SHOULD ALLOW STRENGTHENING UNTIL THE CYCLONE INTERACTS WITH A LARGE MIDDLE- TO UPPER-LEVEL LOW CURRENTLY SEEN OVER HAWAII. THIS UPPER-LOW SHOULD START TO INCREASE THE SHEAR OVER THE SYSTEM IN A COUPLE OF DAYS AND SIGNIFICANTLY WEAKEN LANA BY THE END OF THE FORECAST PERIOD. THE OFFICIAL NHC FORECAST IS CLOSE TO...BUT A LITTLE HIGHER THAN...THE MODEL CONSENSUS INITIALLY...AND IS CLOSE TO THE SHIPS MODEL IN 3-5 DAYS. THE BEST ESTIMATE OF INITIAL MOTION IS 285/17. A MID-LEVEL HIGH LOCATED TO THE NORTHEAST OF HAWAII SHOULD PROVIDE THE STEERING FOR LANA DURING THE NEXT SEVERAL DAYS...KEEPING THE STORM ON A WEST OR WEST-NORTHWEST HEADING. ALL OF THE GLOBAL MODELS WEAKEN THE STRONG MIDDLE-TO UPPER-LEVEL LOW NEAR HAWAII AND SHOW ENOUGH RIDGING TO ALLOW THE STORM TO REMAIN SOUTH OF THE HAWAIIAN ISLANDS. THERE HAS BEEN A NOTICEABLE NORTHWARD SHIFT OF THE STORM TRACK IN THE RECENT GUIDANCE FROM THE GFS/GFDL/HWRF MODELS. THIS CHANGE COULD BE ATTRIBUTED TO THE GFS MODEL HAVING A MORE REALISTIC REPRESENTATION OF THE STORM THAN EARLIER...ALTHOUGH IT IS DIFFICULT TO TELL THE EXACT REASON AT THIS TIME. THE OFFICIAL NHC FORECAST IS SHIFTED TO THE NORTH FROM THE PREVIOUS ONE...BUT STILL LIES SOUTH OF THE MODEL CONSENSUS...SIGNIFICANTLY SO AT THE LONG-RANGE. FORECAST POSITIONS AND MAX WINDS INITIAL 31/0300Z 12.8N 143.1W 50 KT 12HR VT 31/1200Z 13.2N 145.5W 60 KT 24HR VT 01/0000Z 13.7N 148.4W 65 KT 36HR VT 01/1200Z 14.2N 151.2W 65 KT 48HR VT 02/0000Z 14.6N 153.9W 60 KT 72HR VT 03/0000Z 15.2N 159.5W 50 KT 96HR VT 04/0000Z 16.0N 165.5W 35 KT 120HR VT 05/0000Z 16.5N 171.0W 25 KT...REMNANT LOW $$ FORECASTER BLAKE