Tropical Storm SAOLA Advisory 20.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (TWENTYSEVEN)
WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 27W (TWENTYSEVEN), LOCATED APPROXIMATELY 345 NM
EAST-SOUTHEAST OF GUAM, HAS TRACKED SOUTHWARD AT 09 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED MULTI-SPECTRAL SATELLITE IMAGERY
DEPICTS AN AREA OF BUILDING CONVECTION CENTRALLY LOCATED OVER A
LOW-LEVEL CIRCULATION CENTER (LLCC). A 192026Z 27GHZ WINDSAT
MICROWAVE IMAGE DEPICTS FORMATIVE BANDING WRAPPING INTO A CENTRAL
DEEP CONVECTIVE AREA FROM BOTH THE NORTHERN AND SOUTHERN SEMI-
CIRCLES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON THE PGTW SATELLITE FIX AND EXTRAPOLATION FROM A 192224Z OSCAT
IMAGE. THE INITIAL INTENSITY OF 35 KNOTS IS HEDGED SLIGHTLY ABOVE
THE PGTW DVORAK ESTIMATE OF T2.0 (30 KNOTS) AND IS SUPPORTED BY THE
PREVIOUSLY MENTIONED OSCAT IMAGE SHOWING 35 AND 40 KNOT WIND BARBS.
ENVIRONMENTAL ANALYSIS REVEALS THAT THE SYSTEM IS IN AN AREA OF LOW
(5-10 KNOTS) VERTICAL WIND SHEAR (VWS) AND IS TRACKING THROUGH WARM
(31 CELSIUS) SEA SURFACE TEMPERATURES (SSTS). TS 27W HAS DEVELOPED
A POLEWARD OUTFLOW CHANNEL THAT IS FLOWING INTO A TUTT CELL. THE
SYSTEM HAS BEEN TRACKING TO THE SOUTH UNDER THE INFLUENCE OF A NEAR
EQUATORIAL RIDGE LOCATED TO THE SOUTHWEST AND A BUILDING
SUBTROPICAL RIDGE LOCATED TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THE FORECAST PHILOSOPHY HAS CHANGED AS PEAK INTENSITIES HAVE
INCREASED DUE TO A POSSIBLE RAPID INTENSIFICATION SCENARIO.
   B. TS 27W IS FORECAST TO TRACK NORTHWEST OVER THE NEXT 48 HOURS
UNDER THE INFLUENCE OF THE BUILDING SUBTROPICAL RIDGE TO THE
NORTHEAST. AFTER TAU 48, THE SYSTEM WILL TRACK MORE NORTH-NORTHWEST
AS IT ROUNDS THE RIDGE AXIS. DUE TO THE POLEWARD OUTFLOW CHANNEL
BEING ENHANCED BY THE TUTT CELL, A PERIOD OF RAPID INTENSIFICATION
IS FORECAST TO OCCUR THROUGH TAU 36, PEAKING AT 60 KNOTS. AFTER TAU
48, TS 27W WILL BEGIN TO WEAKEN AS THE ENVIRONMENT BECOMES
UNFAVORABLE DUE TO INCREASING VERTICAL WIND SHEAR, THE RESULT OF
THE SYSTEMS PROXIMITY TO TYPHOON 25W. THE WEAKENING TREND WILL
PERSIST UNTIL THE SYSTEM IS ABSORBED BY TY 25W AROUND TAU 96.
DYNAMIC MODEL GUIDANCE IS IN STRONG AGREEMENT IN THE LATER TAUS FOR
THE TRACK DIRECTION. THE INITIAL TRACK DIRECTION HAS NOT TURNED TO
THE NORTHWEST AS RAPIDLY AS FORECAST CAUSING UNCERTAINTY IN THE
INITIAL FORECAST TRACK. THIS UNCERTAINTY, COMBINED WITH THE COMPLEX
NATURE OF THE FORECAST TRACK, LENDS LOW CONFIDENCE IN THE JTWC
TRACK FORECAST.//
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