Tropical Storm LEKIMA Advisory Sat Aug 10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 10W (LEKIMA) WARNING NR 22//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 10W (LEKIMA), LOCATED APPROXIMATELY 126 NM
NORTH-NORTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTHWESTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. A 5-10 NM ROUND EYE IN ANIMATED
MULTISPECTRAL SATELLITE IMAGERY PROVIDES HIGH CONFIDENCE IN THE
INITIAL POSITION. DESPITE THE EYE REMAINING SMALL AND ROUND, ANIMATED
ENHANCED INFRARED SATELLITE IMAGERY REVEALS THE SURROUNDING
CONVECTION HAS BECOME ASYMMETRIC WITH WARMER CLOUD TOP TEMPERATURES
ON THE NORTHERN SIDE. THE INITIAL INTENSITY OF 105 KTS IS BETWEEN
CURRENT INTENSITY ESTIMATES FROM T5.0-6.0 (90-115 KTS) AND IS JUST
UNDER A 090600Z ADT ESTIMATE OF 107 KNOTS. THE ENVIRONMENT HAS GOOD
POLEWARD AND WEAKENING EQUATORWARD OUTFLOW, LOW (10-15 KT)
VERTICAL WIND SHEAR (VWS), AND WARM (29-30 CELSIUS) SEA SURFACE
TEMPERATURE IS CONDUCIVE; HOWEVER, THERE DOES APPEAR TO BE SOME
COMPARATIVELY DRY, CONTINENTAL AIR ENTRAINING IN FROM THE WEST THAT
IS LIKELY CONTRIBUTING TO THE CONTINUED WEAKENING SEEN OVER THE PAST
12 HOURS. TY 10W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. SHORTLY AFTER MAKING LANDFALL ABOUT 170 NM SOUTH OF SHANGHAI,
CHINA AROUND TAU 12, TY 10W WILL BEGIN TRACKING NORTHWARD AS THE STR
REORIENTS AND RECEDES SLIGHTLY TO THE EAST. THE SYSTEM SHOULD PASS
NEAR SHANGHAI ON A NORTHWARD TRACK AROUND TAU 30 AND PASS BRIEFLY
OVER THE YELLOW SEA ON A NORTH-NORTHWESTWARD TRACK BEFORE MAKING A
SECOND LANDFALL NEAR QINGDAO, CHINA PRIOR TO TAU 60. LAND INTERACTION
IS EXPECTED TO WEAKEN THE SYSTEM TO 45 KNOTS BY TAU 72. THE INTENSITY
FORECAST IS VERY UNCERTAIN BECAUSE SMALL SHIFTS IN THE TRACK COULD
SIGNIFICANTLY IMPACT THE AMOUNT OF WEAKENING DUE TO LAND INTERACTION.
NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT FOR
THIS PORTION OF THE FORECAST, LENDING TO GOOD CONFIDENCE IN THE JTWC
TRACK FORECAST THROUGH TAU 72.
   C. BETWEEN TAU 72 AND 120, TY 10W IS EXPECTED TO CONTINUE TRACKING
NORTH-NORTHWESTWARD AND BEGIN ROUNDING THE STR AXIS. HIGH VWS AND
LAND INTERACTION ARE EXPECTED TO CONTINUE WEAKENING THE SYSTEM;
HOWEVER, UNCERTAINTY IN THE INTENSITY FORECAST REMAINS HIGH DUE TO
UNCERTAINTY IN THE AMOUNT OF LAND INTERACTION. NUMERICAL MODEL SPREAD
INCREASES SIGNIFICANTLY AS ALL MODELS (EXCEPT JGSM, WHICH TURNS
SOUTHEAST AFTER TAU 72) FOLLOW THE RECURVE SCENARIO TO VARYING
DEGREES; HOWEVER, WITH FAR DIFFERENT TRACK SPEEDS, WITH A TRACK
SPREAD OF OVER 500 NM AT TAU 120. THE JTWC TRACK FORECAST FAVORS THE
RECURVE SCENARIO WITH LOW CONFIDENCE.//
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