Tropical Storm TAPAH Advisory Sa, 29.04.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (TAPAH) WARNING NR
06//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 06W (TAPAH), LOCATED APPROXIMATELY 99 NM EAST
OF SAIPAN, HAS TRACKED NORTHWARD AT 11 KNOTS OVER THE PAST SIX
HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS
MAINTAINED OVERALL ORGANIZATION AS THE CENTRAL CONVECTION SLIGHTLY
DEEPENED. ADDITIONALLY, GUAM DOPPLER RADAR IMAGERY CONTINUES TO
INDICATE TIGHTLY-CURVED BANDING WRAPPING INTO THE LOW-LEVEL
CIRCULATION CENTER THAT IS NOW AT THE EDGE OF EFFECTIVE RADAR RANGE.
THE INITIAL POSITION IS BASED ON THE ABOVE IMAGES WITH GOOD
CONFIDENCE. THE INITIAL INTENSITY IS BASED ON THE 281730Z DVORAK
ESTIMATE FROM PGTW. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT WITH LOW (05 TO 10 KNOT) VERTICAL WIND SHEAR (VWS) AND
GOOD POLEWARD OUTFLOW; HOWEVER, POLEWARD OUTFLOW IS WEAKENING AS THE
DEEP MID-LATITUDE LOW QUICKLY SHIFTS NORTHEASTWARD. TS 06W IS
TRACKING NORTHWARD ALONG THE WESTERN EDGE OF A MID-LAYERED
SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
   B. TS 06W IS FORECAST TO TRACK NORTHWARD THROUGH TAU 12 THEN
NORTH-NORTHWESTWARD TO NORTHWESTWARD AS THE STR IS EXPECTED TO
SLIGHTLY BUILD. TS 06W IS FORECAST TO INTENSIFY FOR THE NEXT 24
HOURS AS FAVORABLE ENVIRONMENTAL CONDITIONS OF GOOD POLEWARD OUTFLOW
AND WARM SEA SURFACE TEMPERATURES (NEAR 28 DEGREES CELSIUS) PERSIST.
AFTER TAU 24, POLEWARD OUTFLOW IS FORECAST TO WEAKEN AS AN UPPER-
LEVEL RIDGE BUILDS SOUTH OF JAPAN.
   C. IN THE EXTENDED TAUS, TS 06W IS FORECAST TO RE-CURVE
NORTHEASTWARD AHEAD OF AN APPROACHING SHORTWAVE TROUGH AND SHOULD
ENCOUNTER INCREASING VWS, DECREASING SEA SURFACE TEMPERATURES. THE
SYSTEM SHOULD ALSO BEGIN INTERACTING WITH THE COLD BAROCLINIC ZONE
AT WHICH POINT THE SYSTEM IS FORECAST TO QUICKLY ERODE, DISSIPATING
BY TAU 96. THE DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT. THE
TRACK FORECAST IS LAID EAST OF THE MULTI-MODEL CONSENSUS TO OFFSET
UNLIKELY WESTWARD OUTLIERS. DUE TO THE TIGHT GROUPING OF MODEL
GUIDANCE, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.  //
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