Tropical Storm TAPAH Advisory lun, 28-04

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (SIX) WARNING NR
03//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 06W (SIX), LOCATED APPROXIMATELY 134 NM EAST-
SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED NORTHEASTWARD AT 06
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) DEPICTS A RAPIDLY CONSOLIDATING LOW LEVEL CIRCULATION
CENTER WITH IMPROVED BANDING AROUND THE LLCC WHILE AN EYE FEATURE IS
BEGINNING TO TAKE FORM. A 272227Z SSMIS MICROWAVE IMAGE SHOWS THE
MID-LEVEL CIRCULATION HAS BECOME COUPLED WITH LLCC WHICH HAS ALLOWED
FOR A RAPID IMPROVEMENT IN STRUCTURE OVER THE PAST SIX HOURS. THE
INITIAL POSITION IS BASED ON FORMATIVE EYE FEATURE SEEN IN THE MSI
LOOP WITH GOOD CONFIDENCE. THE INITIAL INTENSITY HAS BEEN INCREASED
TO 50 KNOTS, BASED ON THE RAPID IMPROVEMENT IN STRUCTURE WHICH CAN
SEEN BOTH IN THE MSI LOOP AND THE PAST FEW MICROWAVE IMAGES. UPPER-
LEVEL ANALYSIS REVEALS AN FAVORABLE ENVIRONMENT WITH LOW (05 TO 10
KNOTS) VERTICAL WIND SHEAR (VWS) AND VIGOROUS POLEWARD OUTFLOW,
WHICH IS BEING ENHANCED BY A DEEP MIDLATITUDE TROUGH THAT IS LOCATED
TO THE NORTHEAST OF THE SYSTEM. TS 06W IS LOCATED ALONG THE WESTERN
PERIPHERY OF A NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE (STR) AND IS
TRACKING SLOWLY NORTHWARD TOWARD A BREAK IN THE STR CREATED BY THE
AFOREMENTIONED DEEP MIDLATITUDE SHORTWAVE TROUGH.
3. FORECAST REASONING.
   A. THE FORECAST INTENSITIES HAVE BEEN INCREASED DUE TO A RAPID
IMPROVEMENT IN STRUCTURE OVER THE PAST SIX HOURS.
   B. TS 06W IS FORECAST TO CONTINUE TRACKING NORTHWARD ALONG THE
WESTERN PERIPHERY OF THE MID TO DEEP-LAYER REFLECTION OF THE STR
POSITIONED TO THE EAST THROUGH THE NEXT DAY. AFTER WHICH, THE SYSTEM
SHOULD BEGIN TO TRACK NORTH-NORTHWESTWARD AS THE STR BUILDS IN FROM
THE NORTH. TS 06W IS FORECAST TO INTENSIFY FOR THE NEXT 24 HOURS AS
FAVORABLE ENVIRONMENTAL CONDITIONS OF STRONG POLEWARD OUTFLOW AND
WARM SEA SURFACE TEMPERATURES (NEAR 28 DEGREES CELSIUS) PERSIST.
AFTER TAU 24, DECREASING OUTFLOW WILL HINDER FURTHER DEVELOPMENT AS
THE MID-LATITUDE TROUGH IS EXPECTED TO LIFT FURTHER TO THE NORTHEAST.
   C. IN THE EXTENDED TAUS, TS 06W IS FORECAST TO RE-CURVE AHEAD OF
AN APPROACHING SHORTWAVE TROUGH AND SHOULD ENCOUNTER INCREASING
VERTICAL WIND SHEAR, DECREASING SEA SURFACE TEMPERATURES, AND BEGIN
TO INTERACT WITH THE BAROCLINIC ZONE AT WHICH POINT THE SYSTEM IS
FORECAST TO QUICKLY WEAKEN AND DISSIPATE BY TAU 120. NUMERIC MODEL
GUIDANCE HAS STARTED TO SPREAD AS THE TRACKERS GREATLY VARY IN THE
EXTENT OF THE NORTHWEST TURN AFTER TAU 24. NAVGEM AND GFS  HAVE
SHIFTED TO A MORE POLEWARD TRACK WHILE JGSM AND GFDN SHOW A MORE
WESTWARD TRACK, WHICH IS INCONSISTENT WITH THE RECENT STORM MOTION.
DUE TO THIS, LOW CONFIDENCE REMAINS IN THE JTWC FORECAST, WHICH HAS
SHIFTED SLIGHTLY MORE POLEWARD ALONG WITH THE MULTI-MODEL
CONSENSUS.//
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