Tropical Storm FAXAI Advisory Sat Sep 07

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (FAXAI) WARNING NR
022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 14W (FAXAI), LOCATED APPROXIMATELY 581 NM SOUTH-
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWESTWARD AT 17 KNOTS
(KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS TY 14W AS A RAPIDLY INTENSIFYING SYSTEM, MAINTAINING
A VISIBLE EYE FEATURE. A 070000Z HIMAWARI-8 VISIBLE 1KM IMAGE ALONG
WITH A 062354Z AMSU 89GHZ MICROWAVE IMAGE REVEALS A 10 NM EYE
FEATURE, LENDING HIGH CONFIDENCE TO THE PLACEMENT OF THE INITIAL
POSITION. THE INITIAL INTENSITY (75 KTS) IS ASSESSED WITH HIGH
CONFIDENCE BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES
OF T4.5/77KTS FROM PGTW AND RJTD, CONFIRMED BY AN ADVANCED DVORAK
TECHNIQUE ESTIMATE OF T4.4/75KTS. UPPER-LEVEL ANALYSIS REVEALS THE
SYSTEM REMAINS IN A FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (10-
20 KT) VERTICAL WIND SHEAR (VWS) AND WARM (29-30 CELSIUS) SEA
SURFACE TEMPERATURE (SST). CURRENTLY, THERE IS FAIR POLEWARD OUTFLOW
SUPPORTING THE SYSTEM. TY 14W IS TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF A DEEP-LAYER STR CENTERED TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 12, TY 14W WILL CONTINUE ON THE PRESENT TRACK
AROUND THE PERIPHERY OF THE AFOREMENTIONED DEEP-LAYER STR. BETWEEN
TAUS 24 AND 36, THE SYSTEM WILL GRADUALLY SLOW AS IT ROUNDS THE STR
AXIS. AFTER TAU 36, THE STORM WILL SHIFT TO A NORTHEASTWARD TRACK AN
ACCELERATE THROUGH TAU 72. THE SYSTEM IS FORECAST TO MAKE LANDFALL
SOUTHEAST OF TOKYO AROUND TAU 36 AS A SIGNIFICANT TYPHOON WITH A
PEAK INTENSITY OF 105 KTS. THE ENVIRONMENT WILL REMAIN FAVORABLE FOR
THE NEXT 18 HOURS, MAINTAINING LOW VWS AND WARM SST. HOWEVER, MODELS
DEPICT DEVELOPMENT OF A TRANSIENT UPPER-LEVEL ANTICYCLONE TO THE
NORTHWEST OF THE SYSTEM, INDUCING A BRIEF BREAK IN THE POLEWARD
OUTFLOW AND RESULTING IN A SLOWING IN THE RATE OF INTENSIFICATION.
ONCE THIS ANTICYCLONE MOVES TO THE NORTHEAST OF THE SYSTEM BY AROUND
TAU 24, THE OUTFLOW WILL REINTENSIFY, ALLOWING FOR ANOTHER PERIOD OF
ENHANCED INTENSIFICATION PRIOR TO LANDFALL SOUTHEAST OF TOKYO.
FOLLOWING LANDFALL, AS THE SYSTEM TRANSITS NORTHEAST BACK OVER
WATER, COOLER SSTS AND INCREASING VWS WILL COMBINE TO OFFSET THE
STRONG OUTFLOW AND GRADUALLY WEAKEN TY 14W AS IT BEGINS
EXTRATROPICAL TRANSITION. MODEL GUIDANCE IS IN EXCELLENT AGREEMENT
THROUGH THE EARLY PORTION OF THE FORECAST, WITH ONLY 50 NM SPREAD AT
TAU 48 INCREASING TO 90 NM BY TAU 72 WITH ONLY NAVGEM AS A NORTHERLY
OUTLIER, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC TRACK
FORECAST.
   C. BY TAU 96, TY 14W IS FORECAST TO RAPIDLY MOVE NORTHEASTWARD,
BECOME EMBEDDED IN THE DEEP WESTERLY FLOW, AND TRANSITION TO A GALE-
FORCE EXTRATROPICAL LOW. MODEL GUIDANCE REMAINS IN OVERALL GOOD
AGREEMENT THROUGH TAU 96, WITH INCREASING ALONG AND CROSS-TRACK
UNCERTAINTY IN THE LATER TAUS. BASED ON THE INCREASED SPREAD IN THE
GUIDANCE BY TAU 96, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE
JTWC TRACK FORECAST.//
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