WTPA41 PHFO 021443
TCDCP1

TROPICAL STORM LANA DISCUSSION NUMBER  13
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP062009
500 AM HST SUN AUG 02 2009

AT 200 AM HST...1200 UTC...LANA SHOWED NO SIGNS OF WEAKENING IN
SPITE OF THE 25 KT SOUTHWEST SHEAR CALCULATED BY UW-CIMSS TO BE IN
THE AREA. IN FACT...THUNDERSTORMS THAT FORMED 12 HOURS AGO WERE
STILL PRESENT NORTHEAST OF THE LOW LEVEL CIRCULATION CENTER. CLOUD
TOP TEMPERATURES HAVE BEEN STEADY AT -82C...OR ABOUT 52K FEET BASED
ON THE 1200Z HILO RAOB. PHFO AND SAB CAME UP WITH FINAL T NUMBERS
OF 3.0 WHILE JTWC WENT WITH 2.5. THE UW-CIMSS ADT HAD A CI NUMBER
OF 2.9 AT 1200Z AND 3.0 AT 1230Z. THE OFFICIAL INTENSITY ESTIMATE
REMAINS AT 45 KT...BASED ON THE PERSISTENT DEEP CONVECTION AND THE
MAJORITY OF FIXES AT OR CLOSE TO 3.0.

LANA LIES IN DEEP EASTERLY FLOW SOUTH OF A SUBTROPICAL RIDGE LOCATED
NORTH OF HAWAII. GLOBAL MODELS ARE IN GOOD AGREEMENT IN BUILDING
THE LOW- AND MID-LEVEL RIDGE TO THE WEST...KEEPING LANA WELL WITHIN
THE BROAD EASTERLY TRADE WIND BELT. THE WESTERLY FORECAST TRACK WAS
NUDGED SLIGHTLY SOUTH OF THE PREVIOUS TRACK AND REMAINS ON THE
SOUTH SIDE OF THE CLOSELY GROUPED OBJECTIVE AIDES. FORWARD MOTION
IS IN GOOD AGREEMENT WITH MOST OF THE AIDES AND IS AN EXTENSION OF
THE OLD TRACK. 
 
AN UPPER-LEVEL LOW IS FORECAST TO LINGER SOUTHWEST OF KAUAI NEAR 18N
166W FOR THE NEXT 18 TO 24 HOURS...AND IS FORECAST TO MOVE SLOWLY
TO THE NORTHWEST THEREAFTER. SOUTHWEST WINDS ALOFT EAST OF THE LOW
WILL CONTINUE TO RIDE UP OVER THE LOW- AND MID-LEVEL EASTERLIES
RESULTING IN SUBSTANTIAL VERTICAL SHEARING AT LEAST FOR THE NEXT 24
HOURS. THAT SAID...THE FORECAST OF SLOWLY WEAKENING WINDS HAS BEEN
PUSHED BACK 6 HOURS BECAUSE OF LACK OF CHANGE IN INTENSITY OVER THE
LAST 24 HOURS. THE INTENSITY FORECAST IS CLOSE TO ICON...DSHP AND
SHIPS THROUGH 48 HOURS THEN SHIPS AND NGPI THEREAFTER.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/1500Z 14.4N 158.1W    45 KT
 12HR VT     03/0000Z 14.5N 160.4W    40 KT
 24HR VT     03/1200Z 14.8N 163.4W    35 KT
 36HR VT     04/0000Z 15.2N 166.2W    35 KT
 48HR VT     04/1200Z 15.5N 168.9W    30 KT
 72HR VT     05/1200Z 16.1N 174.3W    25 KT...DISSIPATING
 96HR VT     06/1200Z 16.6N 179.6W    20 KT...REMNANT LOW
120HR VT     07/1200Z 17.1N 174.8E    20 KT...REMNANT LOW
 
$$
FORECASTER CRAIG