WDPN31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (IN-FA) WARNING NR 15//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 27W (IN-FA), LOCATED APPROXIMATELY 189 NM SOUTH-
SOUTHEAST OF ANDERSEN AFB, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE 
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND 
GUAM RADAR IMAGERY SHOW A COMPACT SYSTEM WITH A 4-NM PINHOLE EYE. A 
200841Z SSMIS IMAGE INDICATES DEEP CONVECTIVE BANDING WRAPPING 
TIGHTLY INTO THE CONSOLIDATED LOW-LEVEL CIRCULATION CENTER. OVERALL, 
THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION AND RECENT TRACK 
MOTION. THE INITIAL INTENSITY REMAINS ASSESSED AT 100 KNOTS BASED ON 
A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF 102 KNOTS. UPPER LEVEL 
ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND 
SHEAR (VWS) AND NEAR RADIAL OUTFLOW. TY 27W IS TRACKING ALONG THE 
SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE 
NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE. 
   B. TY 27W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD 
THROUGH TAU 48 UNDER THE STEERING INFLUENCE OF THE DEEP STR, WHICH IS
EXPECTED TO REMAIN ENTRENCHED TO THE NORTH. AFTER TAU 48, THE SYSTEM 
WILL BEGIN TO TRACK MORE POLEWARD AS IT ROUNDS THE SOUTHWEST 
PERIPHERY OF THE STR. THE SYSTEM IS EXPECTED TO MAINTAIN RELATIVELY 
FAST TRACK SPEEDS THROUGH TAU 48 WHILE INTENSIFYING TO A PEAK OF 120 
KNOTS NEAR TAU 24.
   C. IN THE EXTENDED TAUS, TY IN-FA WILL BEGIN SLOWING AS IT BEGINS 
TO RE-CURVE POLEWARD IN RESPONSE TO AN APPROACHING MIDLATITUDE
TROUGH. EXTRA-TROPICAL TRANSITION IS EXPECTED TO COMMENCE NEAR TAU
96 AS THE SYSTEM BEGINS TO INTERACT WITH THE BAROCLINIC ZONE AND THE
STRONG MIDLATITUDE WESTERLIES. HIGH VWS VALUES ARE EXPECTED TO
WEAKEN THE SYSTEM AFTER TAU 72. DYNAMIC MODEL GUIDANCE IS IN
TIGHT AGREEMENT THROUGH TAU 120, LENDING HIGH CONFIDENCE TO THE JTWC 
TRACK FORECAST. THE JTWC FORECAST IS POSITIONED CLOSE TO THE MULTI-
MODEL CONSENSUS, WHICH HAS REMAINED CONSISTENT OVER THE PAST DAY.//
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