WDPN31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (KROVANH) WARNING 
NR 08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 20W (KROVANH), LOCATED APPROXIMATELY 386 NM 
NORTH-NORTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WESTWARD AT 10 
KNOTS OVER THE PAST SIX HOURS. ANIMATED EIR SATELLITE IMAGERY 
DEPICTS IMPROVING STRUCTURE WITH TIGHTLY-CURVED BANDS WRAPPING INTO 
THE CENTER. A 161150Z METOP-B MICROWAVE IMAGE ALSO REVEALS 
CONVECTIVE BANDING WRAPPING INTO A WELL-DEFINED MICROWAVE EYE. THE 
CURRENT POSITION IS BASED ON THE EIR LOOP, MICROWAVE EYE FEATURE AND 
CORRESPONDING FIXES FROM PGTW AND RJTD WITH HIGH CONFIDENCE. BASED 
ON THE CURRENT STRUCTURE, THE INITIAL INTENSITY OF 60 KNOTS IS 
HEDGED HIGHER THAN DVORAK INTENSITY ESTIMATES OF T3.5 (55 KNOTS) 
FROM ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES KROVANH 
REMAINS IN A FAVORABLE ENVIRONMENT WITH LOW VWS AND RADIAL OUTFLOW 
AS EVIDENT ON THE WATER VAPOR IMAGERY. ADDITIONALLY, WARM SSTS IN 
THE AREA ARE CONDUCIVE FOR THE INTENSIFICATION. TS 20W CONTINUES TO 
TRACK ALONG THE PERIPHERY OF A SUBTROPICAL STEERING RIDGE TO THE 
NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 20W IS EXPECTED TO TRACK GENERALLY WEST-NORTHWESTWARD ALONG 
THE PERIPHERY OF THE CURRENT STEERING RIDGE FOR THE NEXT 36 HOURS 
BEFORE TURNING POLEWARD AND ROUNDING THE RIDGE AXIS THROUGH TAU 72. 
CONTINUED FAVORABLE ENVIRONMENTAL AND UPPER-LEVEL CONDITIONS WILL 
ALLOW THE SYSTEM TO UNDERGO RAPID INTENSIFICATION, LEADING TO A PEAK 
INTENSITY OF 115 KNOTS BY TAU 48.
   C. IN THE EXTENDED TAUS, TS 20W WILL REMAIN ON THE NORTHEASTWARD 
TRAJECTORY. INCREASING VWS AND COOLER SSTS WILL BEGIN TO WEAKEN THE 
SYSTEM AS IT ACCELERATES INTO THE MIDLATITUDE BAROCLINIC ZONE. 
DYNAMIC MODEL GUIDANCE IS OVERALL IN GOOD AGREEMENT LENDING TO HIGH 
CONFIDENCE IN THE JTWC TRACK FORECAST WHICH IS POSITIONED CLOSE TO 
MULTI-MODEL CONSENSUS.//
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