Tropical Storm MAYSAK Advisory Sun Aug 30

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MAYSAK) WARNING NR
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 10W (MAYSAK), LOCATED APPROXIMATELY 587 NM
SOUTH OF KADENA AB, OKINAWA, HAS TRACKED NORTH-NORTHWESTWARD AT 06
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH FORMATIVE CONVECTIVE BANDING WRAPPING
IN TOWARDS THE CENTER. THE MSI, IN CONJUNCTION WITH AN EXTRAPOLATION
OF A MICROWAVE EYE FEATURE OBSERVED IN A 290427Z AMSR2 36 GHZ
MICROWAVE IMAGE, LENDS GOOD CONFIDENCE TO THE INITIAL POSITION. THE
INITIAL INTENSITY REMAINS AT 55KTS BASED ON MULTIAGENCY DVORAK
CURRENT INTENSITY ESTIMATES OF T3.0-3.5 (45-55 KTS) BY PGTW, RJTD,
AND RCTP. ADDITIONALLY, A 290530Z ADVANCED DVORAK TECHNIQUE ESTIMATE
OF 55 KTS AND A 290452Z SATELLITE CONSENSUS ESTIMATE OF 52 KTS PLACE
GOOD CONFIDENCE IN THE INITIAL INTENSITY. ENVIRONMENTAL ANALYSIS
SHOWS LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), AN ESTABLISHED
EQUATORWARD OUTFLOW CHANNEL, AND VERY WARM (30-31 CELSIUS) SEA
SURFACE TEMPERATURES (SST). THEREFORE, THE ENVIRONMENT IS HIGHLY
FAVORABLE FOR CONTINUED DEVELOPMENT. HOWEVER, CONVERGENT FLOW FROM A
WESTWARD PROPAGATING TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL
POSITIONED EAST-NORTHEAST OF THE LLCC IS CURRENTLY LIMITING
DIVERGENCE OVER THE NORTHEASTERN QUADRANT. OCEAN HEAT CONTENT (OHC)
REMAINS HIGH AND CONDUCIVE FOR DEVELOPMENT DESPITE THE CURRENT SLOW
TRACK SPEED OF THE SYSTEM. TS 10W IS TRACKING SLOWLY WITHIN AN
UNCERTAIN STEERING ENVIRONMENT.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 10W IS FORECAST TO TRACK GENERALLY NORTHWARD AS A
SUBTROPICAL RIDGE (STR) TO THE EAST REORIENTS. THROUGHOUT THIS TIME,
THE ENVIRONMENT WILL REMAIN HIGHLY CONDUCIVE FOR INTENSIFICATION
WITH LOW VWS, ROBUST EQUATORWARD OUTFLOW, AND VERY WARM SST. AS THE
SYSTEM MOVES, THE PREVIOUSLY MENTIONED TUTT CELL WILL CEASE
HINDERING THE SYSTEM AND BEGIN TO ENHANCE POLEWARD OUTFLOW.
INTENSITY GUIDANCE INDICATES THAT RAPID INTENSIFICATION MAY OCCUR IN
THE NEAR TERM WITH THE CURRENT FORECAST REACHING 90 KTS BY TAU 24 AS
TS 10W TRACKS NORTHWARD ALONG THE BUILDING STR. AFTER TAU 36, THE
SYSTEM WILL TURN SLIGHTLY TO A NORTH-NORTHWESTWARD TRACK FOLLOWING
THE WESTERN PERIPHERY OF THE STR. HIGHLY FAVORABLE ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO PERSIST, LEADING TO A PEAK INTENSITY OF
115 KTS BY TAU 48. NUMERICAL MODEL GUIDANCE ARE IN FAIR AGREEMENT
THROUGH TAU 48. HOWEVER, MODEL SPREAD INCREASES TO A CROSS-TRACK
SPREAD OF 170 NM BY TAU 72. THERE ARE TWO MAJOR OUTLIERS AT THIS
POINT, GFS ENSEMBLE TO THE EAST AND JGSM TO THE WEST. OF NOTE, ECMWF
AND UKMET CONVERGE WEST OF THE MULTI-MODEL CONSENSUS WHILE GFS AND
NAVGEM LIE TO THE EAST. THE JTWC FORECAST TRACK IS PLACED NEAR THE
MULTI-MODEL CONSENSUS; HOWEVER, DUE TO THE LARGE SPREAD IN
SOLUTIONS, THERE IS ONLY FAIR CONFIDENCE IN THE INITIAL PORTION OF
THE FORECAST TRACK.
   C. IN THE EXTENDED PERIOD, A CONTINUED REORIENTATION OF THE STR
WILL ALLOW TS 10W TO BEGIN TO ROUND THE STR AXIS AND RECURVE TO A
NORTH-NORTHEASTWARD TRACK AFTER TAU 72. DURING THIS TIME, COOLING
SSTS WILL SLIGHTLY WEAKEN THE SYSTEM BUT INCREASED TRACK SPEED, LOW
VWS, AND FAVORABLE UPPER LEVEL DIVERGENCE WILL ALLOW THE SYSTEM TO
MAINTAIN A STRENGTH OF 100 KTS AT TAU 96. AFTER TAU 96,
SIGNIFICANTLY COOLER SST (24-28 CELSIUS) COMBINED WITH DECREASING
DIVERGENT FLOW ALOFT DUE TO AN INCOMING SHORTWAVE TROUGH WILL WEAKEN
TS 10W TO 70 KTS BY TAU 120 AS THE SYSTEM BEGINS EXTRATROPICAL
TRANSITION. IN THE EXTENDED RANGE, THE MAJORITY OF THE MODEL
SOLUTIONS ARE NEAR THE MULTI-MODEL CONSENSUS WITH THE EXCEPTION OF
THE AFOREMENTIONED OUTLIERS AND GFS MODEL WHICH DIVERGES EASTWARD
AFTER TAU 72. DESPITE THIS, THERE IS OVERALL FAIR CONFIDENCE IN THE
JTWC FORECAST TRACK DUE TO THE LARGE SPREAD IN MODEL SOLUTIONS.//
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