Tropical Storm MITAG Advisory Sáb, 28-09

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (MITAG) WARNING NR
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 19W (MITAG), LOCATED APPROXIMATELY 671 NM
SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED WEST-
NORTHWESTWARD AT 23 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 272330Z METOP-A PARTIAL
ASCAT PASS REVEAL TWO LARGE BANDS OF CONVECTION WRAPPING INTO THE
CENTER OF THE SYSTEM, ONE FROM THE NORTH AND ONE FROM THE SOUTH. THE
ASCAT AMBIGUITIES SHOW AN AREA OF LIGHT AND VARIABLE WINDS
SURROUNDED BY HIGHER WINDS, REVEALING THE LOW-LEVEL CIRCULATION
CENTER (LLCC) AND PROVIDING GOOD CONFIDENCE IN THE INITIAL POSITION.
BASED ON A 272340Z ADVANCED DVORAK TECHNIQUE ESTIMATE OF T2.6 (37
KTS), AN AFOREMENTIONED PARTIAL ASCAT PASS SHOWING A LARGE REGION OF
35-40 KT WINDS, AND A DVORAK CURRENT INTENSITY ESTIMATE OF T2.5 (35
KTS) FROM PGTW, THE INITIAL INTENSITY IS SET AT 40 KTS WITH FAIR
CONFIDENCE. UPPER LEVEL ANALYSIS SHOWS LOW (10-15 KTS) VERTICAL WIND
SHEAR (VWS) AND STRONG EQUATORWARD OUTFLOW AROUND THE SYSTEM. HIGH
(30 CELSIUS) SEA SURFACE TEMPERATURES (SST) MAKE THE OVERALL
ENVIRONMENT FAVORABLE FOR INTENSIFICATION. UNDER THE STEERING
INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE NORTH, TS 19W
CONTINUES TO TRACK WEST-NORTHWESTWARD.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. IN THE SHORT-TERM FORECAST, TS 19W WILL TRACK WEST-
NORTHWESTWARD AROUND THE PERIPHERY OF THE AFOREMENTIONED STR. AT TAU
48, THE SYSTEM WILL SHIFT TO A NORTHWARD TRACK AS IT TRANSITS AROUND
THE AXIS OF THE STR. MAINTAINING HIGH SST AND LOW VWS, TS 19W WILL
STEADILY INTENSIFY AS IT ADVANCES ALONG THE TRACK, TURNING NORTH-
NORTHEASTWARD PRIOR TO TAU 72. THE SYSTEM WILL REACH ITS PEAK
INTENSITY OF 100 KTS WEST OF OKINAWA BY TAU 72. DYNAMIC MODEL
GUIDANCE IS IN FAIR AGREEMENT WITH NOTABLE OUTLIERS TO BOTH THE EAST
AND WEST. SOME UNCERTAINTY MAY BE DUE TO THE SPEED OF THE SYSTEM AND
THE TIMING OF THE RECURVE, RESULTING IN BOTH ALONG- AND CROSS-TRACK
SEPARATION. THUS, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE
JTWC FORECAST TRACK.
   C. AFTER TAU 72, TS 19 WILL CONTINUE ALONG A NORTH-NORTHEASTWARD
TRACK AS IT CRESTS THE STR AXIS. THE UPPER LEVEL OUTFLOW WILL REMAIN
FAVORABLE; HOWEVER, COOLING SST AND INCREASING VWS WILL SLOWLY BEGIN
TO WEAKEN THE SYSTEM. UPON ENTERNG THE SEA OF JAPAN AND INTERACTING
WITH MID-LATITUDE WESTERLIES, THE SYSTEM WILL ACCELERATE AS IT
BEGINS EXTRATROPICAL TRANSITION PRIOR TO TAU 120. ALTHOUGH ALL MODEL
GUIDANCE SHOWS THE SYSTEM RECURVING, THERE ARE SIGNIFICANT
DIFFERENCES IN THE TRACKS, PARTICULARLY ALONG-TRACK. IN ADDITION,
THERE ARE TWO NOTABLE OUTLIERS TO BOTH THE EAST (JGSM) AND WEST
(NAVGEM) OF THE ENVELOPE. AS A RESULT, THERE IS LOW CONFIDENCE IN
THE EXTENDED PORTION OF THE JTWC FORECAST TRACK.//
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