Tropical Storm LINGLING Advisory Wed Sep 04

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (LINGLING) WARNING
NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 15W (LINGLING), LOCATED APPROXIMATELY 396
NM SOUTH-SOUTHWEST OF KADENA AB, HAS TRACKED NORTHWARD AT 09 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS TIGHTLY-CURVED BANDING WRAPPING INTO AN OBSCURED LOW-
LEVEL CIRCULATION CENTER (LLCC). A 030716Z SSMIS 37GHZ IMAGE,
HOWEVER, DEPICTS A SMALL MICROWAVE EYE FEATURE, WHICH SUPPORTS THE
INITIAL POSITION WITH GOOD CONFIDENCE ALTHOUGH THE WARNING POSITION
MAY BE SLIGHTLY (12NM) NNW OF THE ACTUAL POSITION. THE INITIAL
INTENSITY IS ASSESSED AT 60 KNOTS BASED ON AN AVERAGE OF DVORAK
INTENSITY ESTIMATES RANGING FROM T3.5 TO T4.0 (55 TO 65 KNOTS).
ENVIRONMENTAL ANALYSIS SHOWS TS 15W IS EXPERIENCING FAVORABLE (5 TO
10 KNOT) VERTICAL WIND SHEAR. THERE IS A STRONG EQUATORWARD OUTFLOW
CHANNEL, WHILE THE POLEWARD OUTFLOW CHANNEL CONTINUES TO DEVELOP. SEA
SURFACE TEMPERATURES ARE FAVORABLE FOR ADDITIONAL DEVELOPMENT, NEAR
30 DEGREES CELSIUS. TS 15W IS TRACKING NORTHWARD WHILE UNDER THE
INFLUENCE OF A SUBTROPICAL RIDGE (STR), LOCATED TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THE STR LOCATED TO THE EAST WILL BE THE PRIMARY STEERING
FEATURE FOR TS 15W THROUGH TAU 72. FAVORABLE SEA SURFACE TEMPERATURES
AND FAVORABLE VERTICAL WIND SHEAR WILL ALLOW TS 15W TO QUICKLY
INTENSIFY, REACHING 100 KNOTS BY TAU 72. DYNAMIC MODEL GUIDANCE IS IN
FAIR AGREEMENT THAT TS 15W WILL TRACK NORTHWARD TO NORTH-
NORTHEASTWARD THROUGH TAU 36 AND THEN TRACK NORTHWARD. THERE IS A
100NM SPREAD IN MODEL GUIDANCE AT TAU 48 NEAR OKINAWA, THUS, THERE
CONTINUES TO BE SOME UNCERTAINTY IN THE SHORT-TERM FORECAST TRACK.
ADDITIONALLY, THE 03/00Z ECMWF ENSEMBLE INDICATES A SIMILAR SPREAD
IN SOLUTIONS. THE JTWC FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL
CONSENSUS WITH MODERATE CONFIDENCE.
   C. IN THE LONG TERM, TS 15W WILL CONTINUE TO TRACK NORTHWARD WHILE
POSITIONED ALONG THE WESTERN EDGE OF THE STR. AN APPROACHING WEST TO
EAST MOVING SHORTWAVE TROUGH WILL HELP TO ACCELERATE TS 15W
NORTHWARD. AS TS 15W TRACKS NORTHWARD IT WILL BEGIN EXTRATROPICAL
TRANSITION (ETT) BY TAU 96 AND COMPLETE ETT BY TAU 120. DYNAMIC MODEL
GUIDANCE HAS BOTH A LARGE ALONG-TRACK AND CROSS-TRACK DISAGREEMENT
WITH A SPREAD OF 425 NM. THE JTWC FORECAST TRACK IS PLACED NEAR THE
MULTI-MODEL CONSENSUS WITH MODERATE CONFIDENCE.//
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