Tropical Storm MITAG Advisory Mon Sep 30

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (MITAG) WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 19W (MITAG), LOCATED APPROXIMATELY 449 NM
SOUTH-SOUTHWEST OF KADENA AB, HAS TRACKED NORTHWESTWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL IMAGERY (MSI) SHOWS
CONVECTIVE BANDING WRAPPING INTO A LOW LEVEL CIRCULATION CENTER
(LLCC) PARTIALLY OBSCURED BY THE CIRRUS SHIELD. THE POSITION IS
SUPPORTED BY A 290510Z AMSR2 MICROWAVE IMAGE WITH FAIR CONFIDENCE IN
THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 55 KTS
WITH GOOD CONFIDENCE, SUPPORTED BY MULTI-AGENCY DVORAK INTENSITY
ESTIMATES OF T3.5 (55 KNOTS). UPPER LEVEL ANALYSIS REVEALS MODERATE
(10-20 KTS) VERTICAL WIND SHEAR (VWS) AND EXCELLENT EQUATORWARD
OUTFLOW. THE CONVECTION IS LARGELY DISPLACED TO THE SOUTH OF THE LLCC
AS UPPER LEVEL CONVERGENCE TO THE NORTH IS LIMITING CONVECTION IN
THAT REGION. AT 28-29 CELSIUS, SEA SURFACE TEMPERATURE (SST) REMAINS
FAVORABLE. OVERALL, THE ENVIRONMENT IS FAVORABLE FOR INTENSIFICATION.
TS 19W IS UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR)
TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 48, TS 19W WILL TRANSITION AROUND THE STR AXIS, AND
THEN GRADUALLY TURN NORTH-NORTHEASTWARD THROUGH TAU 72. BY TAU 36, AS
THE SYSTEM CRESTS THE STR AXIS, FORECAST INTENSITY WILL PEAK AROUND
75 KTS. DESPITE A SUPPORTIVE ENVIRONMENT WITH INCREASED UPPER LEVEL
OUTFLOW, TS 19W WILL BE TEMPERED BY FRICTIONAL EFFECTS FROM LAND
INTERACTION AND INCREASING VWS AS IT TRACKS ALONG THE COAST OF CHINA.
MODEL GUIDANCE IS IN FAIR AGREEMENT WITH A CROSS-TRACK SPREAD AT TAU
72 OF 140 NM. JGSM REMAINS THE SOLE OUTLIER TO THE EAST. THE JTWC
FORECAST TRACK IS PLACED NEAR MODEL CONSENSUS, LENDING FAIR
CONFIDENCE TO THIS PORTION OF THE TRACK.
   C. AFTER TAU 72, TS 19W TURNS NORTHEASTWARD, AND BEGINS TO
INTERACT WITH THE MID-LATITUDE WESTERLIES, AND STARTS TO UNDERGO
EXTRATROPICAL TRANSITION (ETT). DESPITE CONTINUED FAVORABLE UPPER
LEVEL OUTFLOW, COOL SST,  HIGH VWS, AND LAND INTERACTION WILL BEGIN
TO ERODE TS 19W AS IT TRANSITS TOWARD THE KOREAN PENINSULA AND ACROSS
THE SEA OF JAPAN. ETT IS EXPECTED TO BE COMPLETE BY TAU 120.
NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH THE RECURVE PORTION OF
FORECAST. HOWEVER, WITH SUFFICIENT DIFFERENCES IN THE TIMING OF THE
RECURVE, CONFIDENCE IN THE JTWC FORECAST TRACK REMAINS FAIR.//
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