Tropical Storm PODUL Advisory 8月27日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (THIRTEEN)
WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 13W (THIRTEEN), LOCATED APPROXIMATELY 402
NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION WITH
FLARING DEEP CONVECTION OVER THE WESTERN SEMICIRCLE. A 261735Z AMSR
89GHZ MICROWAVE IMAGE INDICATES FRAGMENTED BANDING WRAPPING INTO A
BROAD LLCC, THEREFORE, THERE IS POOR CONFIDENCE IN THE CURRENT
POSITION. THE CURRENT INTENSITY IS ASSESSED AT 25 KNOTS BASED ON A
RJTD DVORAK ESTIMATE OF T1.5 (25 KNOTS) AND A 261301Z PARTIAL ASCAT
IMAGE SHOWING A LARGE SWATH OF 20-25 KNOT WINDS IN THE EASTERN
SEMICIRCLE. ENVIRONMENTAL ANALYSIS REVEALS A MARGINALLY FAVORABLE
ENVIRONMENT WITH MODERATE TO STRONG (20-30) VERTICAL WIND SHEAR
OFFSET BY MODERATELY FAVORABLE DIFFLUENCE ALOFT AND WARM SST
(28-30C). TD 13W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF
A SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. IN THE NEAR TERM, TD 13W WILL TRACK WEST-NORTHWESTWARD MAKING
LANDFALL OVER EASTERN LUZON NEAR TAU 24. DUE TO THE MARGINALLY
FAVORABLE ENVIRONMENT, THE SYSTEM IS EXPECTED TO INCREASE TO MINIMAL
TROPICAL STORM STRENGTH (35 KNOTS) AT TAU 24. TD 13W WILL WEAKEN AS
IT CROSSES LUZON BUT SHOULD RE-INTENSIFY TO 45 KNOTS BY TAU 72. THE
SYSTEM IS EXPECTED TO CONTINUE TRACKING WESTWARD TO
WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR POSITIONED
TO THE NORTH THROUGH TAU 72.
   C. AFTER TAU 72, A DEEP SHORTWAVE TROUGH IS FORECAST TO DIG OVER
EASTERN CHINA WHICH WILL WEAKEN THE STR AND ALLOW THE SYSTEM TO TURN
MORE POLEWARD TOWARD HAINAN ISLAND. THE SYSTEM IS EXPECTED TO
MAINTAIN INTENSITY THROUGH TAU 96 AS IT PASSES ALONG THE SOUTHERN
EDGE OF HAINAN. AFTER TAU 96, TD 13W SHOULD STEER WEST-NORTHWESTWARD
AS IT TRANSITIONS TO THE WESTERN STR WITH SLIGHT WEAKENING AS IT
BEGINS TO INTERACT WITH VIETNAM. THE DYNAMIC MODEL GUIDANCE IS IN
FAIR AGREEMENT WITH TWO OUTLIERS (NAVGEM AND JGSM), THEREFORE, THERE
IS LOW CONFIDENCE IN THE FORECAST TRACK.//
NNNN
NNNN