Tropical Storm TAPAH Advisory 28 Απρ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX) WARNING
NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 06W (SIX), LOCATED APPROXIMATELY 126 NM
SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED NORTHWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY (EIR) DEPICTS A FLARING CENTRAL DENSE OVERCAST (CDO) FEATURE
ASSOCIATED WITH A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC).
A 271704Z SSMI 37 GHZ MICROWAVE IMAGE DEPICTS THE LLCC IS SLIGHTLY
DISPLACED TO THE WEST FROM THE MID-LEVEL CIRCULATION WHILE THE
CONVECTIVE STRUCTURE HAS SLIGHTLY IMPROVED. THE INITIAL POSITION IS
BASED ON THE MICROWAVE IMAGE AS WELL AS THE EIR LOOP WITH LOW
CONFIDENCE DUE TO THE CDO FEATURE OBSCURING THE LLCC IN THE EIR LOOP
AND SOME AMBIGUITY IN THE SSMI IMAGE. THE INITIAL INTENSITY HAS BEEN
INCREASED TO 30 KNOTS, BASED ON DVORAK INTENSITY ESTIMATES OF THE
SAME VALUE FROM PGTW AND KNES AND IS CONSISTENT WITH THE SLIGHT
IMPROVEMENT IN STRUCTURE. UPPER-LEVEL ANALYSIS REVEALS AN
ESTABLISHED ANTICYCLONE OVER THE SYSTEM, WHICH IS PRODUCING A
FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW (05 TO 10 KNOTS) VERTICAL
WIND SHEAR (VWS) AND EXCELLENT POLEWARD OUTFLOW, WHICH IS BEING
ENHANCED BY A DEEP MIDLATITUDE TROUGH THAT IS LOCATED TO THE NORTH
OF THE SYSTEM. TD 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. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 06W IS FORECAST TO CONTINUE TRACKING NORTHWARD ALONG THE
WESTERN PERIPHERY OF THE LOW-TO MID-LEVEL STR POSITIONED TO THE EAST
THROUGH THE NEXT DAY. AFTER WHICH, THE SYSTEM SHOULD SLOWLY TRACK
NORTHWESTWARD AS THE STR BUILDS TO THE NORTH. TD 06W IS FORECAST TO
CONTINUE SLOWLY INTENSIFY AS THE LLCC ORGANIZES AND FAVORABLE
ENVIRONMENTAL CONDITIONS OF GOOD POLEWARD OUTFLOW AND WARM SEA
SURFACE TEMPERATURES (NEAR 28 DEGREES CELSIUS) PERSIST. AFTER TAU
48, INTERACTION WITH A WEAK BAROCLINIC ZONE ALONG WITH DECREASED
OUTFLOW IS EXPECTED TO HINDER FURTHER DEVELOPMENT.
   C. IN THE EXTENDED TAUS, TD 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. AVAILABLE
DYNAMIC GUIDANCE IS LIMITED BUT IS IN GOOD AGREEMENT, HOWEVER, DUE
TO UNCERTAINTY IN THE INITIAL POSITION AND THE TIMING OF THE
NORTHWESTWARD TURN, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC
FORECAST.//
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