Tropical Storm MAN-YI Advisory 11月20日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 33W (THIRTYFOUR)
WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 34W (THIRTYFOUR), LOCATED APPROXIMATELY 337
NM EAST-SOUTHEAST OF CHUUK, HAS TRACKED WEST-NORTHWESTWARD AT 09
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS FLARING CONVECTION WHICH IS CONTINUING TO CONSOLIDATE
AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION
IS PLACED WITH POOR CONFIDENCE AND IS BASED ON A 191806Z GMI 89 GHZ
MICROWAVE IMAGE WHICH SHOWS THE BROAD NATURE OF THE CONVECTION. THE
INITIAL INTENSITY OF 25 KNOTS IS BASED ON A DVORAK CURRENT INTENSITY
(CI) ESTIMATE OF T1.5 (25 KNOTS) FROM PGTW. TD 34W IS EXPERIENCING
FAVORABLE VERTICAL WIND SHEAR (10 TO 15 KNOTS). POLEWARD AND
EQUATORWARD OUTFLOW CHANNELS ARE WEAK BUT CONTINUE TO DEVELOP. SEA
SURFACE TEMPERATURES ALSO REMAIN FAVORABLE, BETWEEN 28 AND 29 DEGREES
CELSIUS. TD 34W IS TRACKING WESTWARD LONG THE SOUTHERN EDGE OF THE
SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTH.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY.
   B. THOUGH TAU 72, TD 34W WILL TRACK NORTHWESTWARD ALONG THE
SOUTHERN EDGE OF THE STR WHICH IS LOCATED TO THE NORTH. FAVORABLE
VERTICAL WIND SHEAR AND SEA SURFACE TEMPERATURES WILL ALLOW TD 34W TO
REACH AN INTENSITY OF 65 KNOTS BY TAU 36. THE STR TO THE NORTH WILL
BE THE PRIMARY STEERING FEATURE FOR TD 34W IN THE SHORT TERM. THE STR
WILL SHIFT SLIGHTLY TO THE EAST AND TD 34W WILL TRACK AROUND ITS
WESTERN EDGE. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THAT TD 34W
WILL TRACK NORTHWESTWARD. HOWEVER, DUE TO THE UNCERTAINTY IN THE
INITIAL POSITION THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.
AS THE STORM CONSOLIDATES AND IT BECOMES EASIER TO LOCATE THE LLCC
THE CONFIDENCE IN THE FORECAST TRACK WILL LIKELY INCREASE. HOWEVER,
BECAUSE OF THE POORLY DEFINED LLCC THERE IS LOW CONFIDENCE IN THE
FORECAST TRACK.
   C. AFTER TAU 72, TD 34W WILL BEGIN TO TURN MORE NORTHWARD AS IT
ROUNDS THE WESTERN EDGE OF THE STR. AN APPROACHING SHORTWAVE TROUGH
WILL ALSO HELP TO TURN TD 34W NORTHWARD AND THEN NORTHEASTWARD.
FAVORABLE SEA SURFACE TEMPERATURES AND FAVORABLE VERTICAL WIND SHEAR
WILL ALLOW TD 34W TO REACH A PEAK INTENSITY OF 100 KNOTS BY TAU 120.
DYNAMIC MODEL GUIDANCE IS IN AGREEMENT THAT TD 34W WILL MAKE A
NORTHWARD TURN BUT THE TIMING AND SHARPNESS OF THE TURN REMAINS
UNCERTAIN. THEREFORE, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE
JTWC FORECAST TRACK.//
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