Tropical Storm IN-FA Advisory Вс, 22.11.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (IN-FA) WARNING NR 20//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 27W (IN-FA), LOCATED APPROXIMATELY 198 NM NORTH OF
YAP, HAS TRACKED WEST-NORTHWESTWARD AT 15 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE SHOWS AN EXPANSION OF
CONVECTIVE BANDING ALONG THE NORTHERN HALF OF THE SYSTEM. A
NOTICEABLE WEAKENING OF THE POLEWARD OUTFLOW CHANNEL CAN BE OBSERVED
IN THE EIR IMAGERY. OVER THE PAST 12 HOURS DVORAK ESTIMATES FROM
PGTW, KNES, AND RJTD HAVE SHOWN A SLOW WEAKENING TREND, WHICH
MATCHES THE RECENT LOSS OF THE EYE, AS IT HAS BECOME CLOUD-FILLED.
GIVEN THE OBSERVED WEAKENING TREND AND LOSS OF ORGANIZATION IN THE
UPPER LEVEL OUTFLOW PATTERN, THE INITIAL INTENSITY HAS BEEN
DECREASED TO 110 KNOTS. A MINOR INCREASE IN VERTICAL WIND SHEAR AS
TY 27W TRACKS CLOSER TO THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE NORTH HAS STIFLED STRONGER INTENSIFICATION IN THE LAST SIX
HOURS. THE STR ANCHORED TO THE NORTH REMAINS THE PRIMARY STEERING
INFLUENCE, MAINTAINING THE SYSTEM ON A WEST-NORTHWESTWARD TRACK.
   A. THE INTENSITY TREND HAS SHIFTED FROM A MARGINAL INCREASE IN
THE 12 TO 24 HOUR RANGE, TO A STEADY-STATE TREND OVER THE NEXT 12
HOURS WITH THE BEGINNING OF A WEAKENING TREND BEYOND TAU 12. THE
TRACK FORECAST PHILOSOPHY REMAINS UNCHANGED.
   B. TY 27W IS FORECAST TO MAINTAIN A WEST-NORTHWESTWARD TRACK
THROUGH TAU 36 UNDER THE STEERING INFLUENCE OF THE DEEP LAYERED STR
TO THE NORTH. BEYOND THAT, THE SYSTEM WILL TRACK MORE POLEWARD AS IT
ROUNDS THE SOUTHWESTERN PERIPHERY OF THE STR, AS AN APPROACHING MID-
LATITUDE TROUGH CREATES A WEAKNESS ALONG THE WESTERN EXTENT OF THE
STR. A STEADY INCREASE IN VWS WITH A SLOW DECREASE IN SEA SURFACE
TEMPERATURES WILL START THE WEAKENING TREND OVER THE NEXT 12 TO 24
HOURS AS TY IN-FA TRACKS TO THE NORTHWEST THROUGH TAU 36. BEYOND TAU
36, AS THE TRACK TAKES A NORTHEASTERN TURN AROUND THE AXIS OF THE
STR, THE ENVIRONMENTAL CONDITIONS WILL QUICKLY BECOME UNFAVORABLE,
LEADING TO AN INCREASED WEAKENING TREND THROUGH TAU 72.
   C. IN THE EXTENDED FORECAST, TY IN-FA WILL ACCELERATE AS IT
TRACKS TO THE NORTHEAST, BEGINNING TO INTERACT WITH THE MID-LATITUDE
WESTERLIES. EXTRA-TROPICAL TRANSITION IS EXPECTED TO COMMENCE NEAR
TAU 96. HIGH VWS IS EXPECTED TO CONTINUE TO ERODE THE SYSTEM THROUGH
THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE REMAINS IN
TIGHT AGREEMENT THROUGH TAU 120, LENDING TO HIGH CONFIDENCE TO THE
JTWC TRACK FORECAST WHICH IS POSITIONED CLOSE TO THE MULTI- MODEL
CONSENSUS.//
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