Tropical Storm LEKIMA Advisory Mon Aug 05

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (LEKIMA) WARNING NR
05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 10W (LEKIMA), LOCATED APPROXIMATELY 479 NM
SOUTH-SOUTHEAST OF KADENA AB, HAS TRACKED NORTH-NORTHWESTWARD AT 06
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) REVEALS AN EXPOSED, BROAD LOW LEVEL
CIRCULATION (LLC) WITH DEEP CONVECTION WRAPPING INTO THE CENTER FROM
THE SOUTH. THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION PLACED
USING THE MSI AND SHALLOW BANDING IN A 042238Z SSMIS 91 GHZ
MICROWAVE IMAGE. THE INITIAL INTENSITY OF 35 KTS IS CONSISTENT WITH
MULTI-AGENCY DVORAK ESTIMATES OF T2.5 (35 KTS). THE ENVIRONMENT IS
FAVORABLE WITH RADIAL OUTFLOW, WARM (29-30 CELSIUS) SEA SURFACE
TEMPERATURE, AND LOW (10-15 KT) VERTICAL WIND SHEAR (VWS). TS 10W IS
TRACKING SLOWLY ALONG THE SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE
(STR) THAT IS BEING DISTORTED BY TS 09W.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE OVERALL FORECAST PHILOSOPHY SINCE
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 48, TS 10W IS EXPECTED TO CONTINUE TRACKING
NORTHWESTWARD AND SLOWLY ACCELERATE AS TS 09W MOVES AWAY AND THE STR
BUILDS BEHIND IT. THE FAVORABLE ENVIRONMENT SHOULD SUPPORT STEADY
INTENSIFICATION TO 65 KTS BY TAU 72. UNCERTAINTY IN THE MODEL TRACK
GUIDANCE FOR THIS PORTION OF THE FORECAST IS VERY HIGH AS THREE
OUTLIERS (UKMET AND GALWEM TO THE NORTH, NAVGEM TO THE SOUTH) DIFFER
SIGNIFICANTLY FROM THE REMAINING MEMBERS AND THE JTWC TRACK
FORECAST. AT TAU 72, SPREAD IS OVER 230 NM RESULTING IN LOW
CONFIDENCE IN THE FORECAST TRACK THROUGH TAU 72.
   C. BEYOND TAU 72, TS 10W IS EXPECTED TO GRADUALLY TURN MORE
POLEWARD AS IT ROUNDS THE STR AXIS. ASSUMING THE SYSTEM FOLLOWS THE
FORECAST TRACK, THE FAVORABLE ENVIRONMENT SHOULD CONTINUE AND ALLOW
INTENSITY TO REACH 90 KTS BY TAU 120. TRACK SPREAD EXCEEDS 950 NM BY
TAU 120, WITH MEMBERS PLACING THE CENTER BETWEEN CENTRAL CHINA AND
JUST SOUTH OF JAPAN. THE HIGH UNCERTAINTY IN THE TRACK GUIDANCE
COULD GREATLY AFFECT THE ENVIRONMENTAL AND LAND INTERACTION EFFECTS,
RESULTING IN HIGH UNCERTAINTY IN THE INTENSITY FORECAST. BASED ON
THE VERY HIGH SPREAD IN THE MODEL GUIDANCE, THERE IS LOW CONFIDENCE
IN THE JTWC TRACK FORECAST.//
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