Tropical Storm SAOLA Advisory 22 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN)
WARNING NR 09//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 27W (TWENTYSEVEN), LOCATED APPROXIMATELY
200 NM SOUTHEAST OF HAGATNA, GUAM, HAS TRACKED WEST-SOUTHWESTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS FLARING, INTENSE CONVECTION OVER THE
NORTHERN SEMI-CIRCLE OF THE LOW-LEVEL CIRCULATION CENTER. A 211822Z
SSMIS 91GHZ INDICATES A SLIGHT IMPROVEMENT IN ORGANIZATION OVER THE
PAST DAY WITH FORMATIVE DEEP CONVECTIVE BANDING WRAPPING AROUND A
DEFINED CENTER. THE INITIAL INTENSITY IS ASSESSED AT 30 KNOTS,
HEDGED HIGHER THAN DVORAK ESTIMATES OF T1.5 FROM KNES AND PGTW,
BASED ON A RECENT ASCAT IMAGE SHOWING 25 TO 30 KNOT WINDS OVER THE
NORTHERN SEMI-CIRCLE. UPPER-LEVEL ANALYSIS INDICATES MODERATE TO
STRONG (25 TO 35 KNOTS) EASTERLY VERTICAL WIND SHEAR OFFSET BY
STRONG DIFFLUENCE ALOFT, ENHANCED BY A WEAKENING TUTT CELL NEAR 28N
153E. TD 27W IS TRACKING SLOWLY WEST-SOUTHWESTWARD WITHIN A
COMPETING STEERING ENVIRONMENT.
3. FORECAST REASONING.
   A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   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 NORTHERLY WINDS AT 850-
600MB, PRODUCING THE SLOW WEST-SOUTHWESTWARD TRACK THROUGH TAU 36.
HOWEVER, THIS SOUNDING SHOWS INCREASING EASTERLY FLOW ABOVE 600MB,
WHICH SUGGESTS A WEAKENING NER AND BUILDING STR AS FORECAST BY THE
MODELS. THE TUTT CELL TO THE NORTH, WHICH IS CURRENTLY AIDING
OUTFLOW, IS FORECAST TO WEAKEN WITH WEAK EASTERLY DIFFLUENT FLOW AND
INCREASING VERTICAL WIND SHEAR PERSISTING OVER THE SYSTEM THROUGH
TAU 36. THIS WILL LIMIT INTENSIFICATION THROUGH TAU 48. AFTER TAU
48, ENVIRONMENTAL CONDITIONS ARE FORECAST TO IMPROVE LEADING TO A
PERIOD OF INTENSIFICATION / CONSOLIDATION. DYNAMIC AIDS ARE IN GOOD
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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