Tropical Storm MITAG Advisory 29 Σεπ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (MITAG) WARNING NR
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 19W (MITAG), LOCATED APPROXIMATELY 510 NM
SOUTH OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WESTWARD AT 13 KNOTS
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS A BROAD AREA OF CONVECTIVE BANDS SPIRALING INTO A
PARTIALLY OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). WITH THE
PRESENCE OF THE CIRRUS SHIELD AND SOME FLARING CONVECTION, THE LLCC
IS DIFFICULT TO TRACK, PLACING LOW CONFIDENCE IN THE INITIAL
POSITION. BASED ON A DVORAK ESTIMATE OF T3.0 (45 KTS) FROM PGTW, THE
INITIAL INTENSITY IS SET AT 50 KTS (BELOW A SATCON INTENSITY
ESTIMATE OF 53 KTS) AS THERE HAVE NOT BEEN ANY INDICATIONS OF
STRENGTHENING IN THE LAST SIX HOURS. THE UPPER LEVEL ENVIRONMENT IS
CHARACTERIZED BY LOW (5-10 KT) VERTICAL WIND SHEAR (VWS) ALONG WITH
STRONG EQUATORWARD OUTFLOW AND FAIR POLEWARD OUTFLOW. SEA SURFACE
TEMPERATURE (SST) REMAINS HIGH AT 28-29 CELSIUS, MAINTAINING AN
OVERALL FAVORABLE ENVIRONMENT FOR CONTINUED DEVELOPMENT. A
SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTH IS STEERING TS 19W
ALONG A NORTHWESTWARD TRACK.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 72, TS 19W WILL GRADUALLY TURN NORTH-NORTHEASTWARD
AS IT ROUNDS THE STR AXIS. AROUND TAU 48, THE INTENSITY WILL
PEAK AROUND 80 KTS. AFTER TAU 48, THE INTENSITY WILL SLOWLY WEAKEN AS
TS 19W EXPERIENCES FRICTIONAL EFFECTS FROM LAND INTERACTION, PASSING
WITHIN 100 NM OF CHINA AROUND TAU 60, AND INCREASING VWS. MODEL
GUIDANCE FOR THE SHORT-TERM FORECAST IS IN FAIR AGREEMENT,
INCREASING TO A CROSS-TRACK SPREAD OF 116 NM AT TAU 72 WITH ECMWF
(WEST) AND JGSM (EAST) AS OUTLIERS TO THE MODEL ENVELOPE. THUS,
THERE IS FAIR CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.
   C. AFTER TAU 72, TS 19W TRACKS NORTHEASTWARD AS IT BEGINS
INTERACTING WITH THE MID-LATITUDE WESTERLIES AND BEGIN EXTRATROPICAL
TRANSITION (ETT). COOLING SST AND INCREASING VWS WILL BEGIN TO
ENHANCE THE EROSION OF THE SYSTEM DESPITE PERSISTING FAVORABLE UPPER
LEVEL OUTFLOW. ADDITIONALLY, LAND INTERACTION WITH KOREA PRIOR TO
TAU 96 WILL CREATE FRICTIONAL EFFECTS, FURTHER WEAKENING THE SYSTEM.
ETT IS EXPECTED TO BE COMPLETE BY TAU 120. ALL MODEL GUIDANCE DEPICT
THE RECURVE OF TS 19W; HOWEVER, THERE ARE SUFFICIENT DIFFERENCES IN
TIMING AND SPEED OF RECURVE AMONG THE MODELS TO KEEP CONFIDENCE IN
THE TRACK AS FAIR.//
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