Tropical Storm SAOLA Advisory dom, 22-10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN)
WARNING NR 10//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 27W (TWENTYSEVEN), LOCATED APPROXIMATELY
240 NM SOUTHEAST OF HAGATNA, GUAM, HAS TRACKED SOUTHWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS AN EXPOSED, DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
PERSISTENT DEEP CONVECTION OVER THE WESTERN SEMI-CIRCLE. THE INITIAL
INTENSITY IS ASSESSED AT 30 KNOTS BASED ON DVORAK INTENSITY
ESTIMATES OF T2.0 (30 KNOTS) FROM KNES AND PGTW, CONSISTENT WITH A
RECENT ASCAT IMAGE SHOWING 25 TO 30 KNOT WINDS OVER THE SOUTHWEST
QUADRANT. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH
MODERATE TO STRONG (25 TO 35 KNOTS) EASTERLY VERTICAL WIND SHEAR
(VWS). TD 27W IS TRACKING ERRATICALLY WITHIN A COMPETING STEERING
ENVIRONMENT.
3. FORECAST REASONING.
   A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE, HOWEVER, THE DEGRADING ENVIRONMENTAL
CONDITIONS AND SOUTHWARD TRACK MAY LEAD TO DISSIPATION OVER THE NEXT
24 TO 36 HOURS IF THE SYSTEM FAILS TO SURVIVE.
   B. TD 27W IS POSITIONED WITHIN A COMPETING STEERING ENVIRONMENT
WITH A LOW-LEVEL (700MB) SUBTROPICAL RIDGE (STR) TO THE NORTH AND
NORTHEAST, AND A NEAR-EQUATORIAL RIDGE (NER) TO THE WEST AND
SOUTHWEST. A RECENT GUAM UPPER-AIR SOUNDING SUPPORTS THE PRESENCE OF
THE NER POSITIONED WEST OF GUAM WITH NORTH-NORTHWESTERLY WINDS AT
850-700MB, WHICH WILL PRODUCE A SOUTHWARD TO SOUTHWESTWARD TRACK
THROUGH TAU 12. HOWEVER, THIS SOUNDING SHOWS INCREASING EASTERLY
FLOW ABOVE 700MB, WHICH SUGGESTS A WEAKENING NER AND BUILDING STR AS
FORECAST BY THE MODELS. PERSISTENT VWS WILL LIMIT INTENSIFICATION
THROUGH TAU 24 TO 36. AFTER TAU 36, ENVIRONMENTAL CONDITIONS ARE
FORECAST TO IMPROVE LEADING TO A PERIOD OF SLOW INTENSIFICATION /
CONSOLIDATION. DYNAMIC AIDS ARE IN FAIR AGREEMENT AFTER TAU 36 WITH
SOLUTIONS ACCELERATING TD 27W WEST-NORTHWESTWARD TO NORTHWESTWARD AS
THE STR ASSUMES STEERING CONTROL.
   C. IN THE EXTENDED PERIOD, TD 27W IS FORECAST TO RE-CURVE
POLEWARD TOWARD A WEAKNESS IN THE STR. IMPROVED POLEWARD VENTILATION
WILL ALLOW TD 27W TO INTENSIFY TO A PEAK INTENSITY OF 65 KNOTS BY
TAU 120. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST DUE
TO UNCERTAINTY IN THE TRACK IN THE EARLY PORTION OF THE FORECAST.
AFTER TAU 120, STRONG ZONAL WESTERLIES ARE FORECAST TO PERSIST OVER
JAPAN MAKING LANDFALL OVER MAINLAND JAPAN EXTREMELY UNLIKELY.//
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