Tropical Storm USAGI Advisory 11月20日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 33W (THIRTYTHREE)
WARNING NR 11//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 33W (THIRTYTHREE), LOCATED APPROXIMATELY 323
NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED
WEST-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A RAGGED AND EXPOSED
LOW LEVEL CIRCULATION WITH WEAK FRAGMENTED CONVECTION SHEARED
WESTWARD. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED
IN THE EIR AND PAGASA RADAR LOOPS. THE INITIAL INTENSITY OF 25 KNOTS
IS BASED ON THE DVORAK CURRENT INTENSITY ESTIMATE OF T1.5/25KTS FROM
RJTD. THE ENVIRONMENT IS OVERALL UNFAVORABLE WITH GOOD UPPER LEVEL
OUTFLOW AND WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE (SST) BEING
OFFSET BY MODERATE TO HIGH (20-25 KNOT) VERTICAL WIND SHEAR (VWS) AND
LAND INTERACTION. TD 33W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF
A HIGH-ZONAL SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A.  THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 72, TD 33W IS EXPECTED TO CONTINUE TRACKING
WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STR. THE SYSTEM WILL
STRUGGLE TO CONSOLIDATE AS IT DRAGS ACROSS THE VISAYAN ISLANDS.
HOWEVER, AFTER TAU 24, IT WILL EXIT INTO THE SOUTH CHINA SEA AND
QUICKLY REGROUP AND INTENSIFY AS VWS RELAXES AND FAVORABLE SST AND
OUTFLOW RESUME, PEAKING AT 65 KNOTS BY TAU 72 AS IT APPROACHES
VIETNAM. SPREAD IN THE NUMERICAL MODEL GUIDANCE IS MINIMAL, LENDING
HIGH CONFIDENCE TO THIS PORTION OF THE JTWC FORECAST TRACK.
   C. AFTER TAU 72, TD 33W WILL BEGIN TO SLOWLY TURN POLEWARD AS IT
ROUNDS THE STR AXIS. HIGH VWS AND LAND INTERACTION SHOULD CAUSE THE
SYSTEM TO WEAKEN TO 30 KNOTS BY TAU 120 AS IT SKIRTS THE VIETNAMESE
COAST. SPREAD IN THE MODEL GUIDANCE INCREASES SIGNIFICANTLY WITH NVGM
ON THE EXTREME RIGHT AND JGSM ON THE LEFT MARGIN OF THE MODEL
ENVELOPE. BASED ON THIS, THERE IS LOW CONFIDENCE IN THE EXTENDED
PORTION OF THE JTWC TRACK FORECAST, WHICH IS PLACED JUST TO THE LEFT
OF THE MODEL CONSENSUS TO OFFSET NVGM.//
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