WDPN31 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (JANGMI) WARNING NR 
07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 23W (JANGMI), LOCATED APPROXIMATELY 352 NM
SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 09
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY (EIR), ALONG WITH RADAR ANIMATION FROM CEBU STATION, 
PHILIPPINES, REVEALS THAT TS JANGMI HAS INTENSIFIED AS IT TRACKED 
ACROSS THE SURIGAO STRAIT AS THE LOW LEVEL CIRCULATION HAS BECOME 
MORE TIGHTLY WRAPPED AND BETTER DEFINED DESPITE A SHALLOWING OF THE 
DEEP CONVECTIVE BANDING AS THE SYSTEM MAKES LANDFALL ACROSS BOHOL 
ISLAND. A 290946Z SSMIS PASS FURTHER REVEALED A FORMATIVE MICROWAVE 
EYE FEATURE AS THE SYSTEM TRACKED ACROSS THE STRAIT. THERE IS GOOD 
CONFIDENCE IN THE INITIAL POSITION AND MOTION OF THE SYSTEM BASED ON 
THIS DATA. THE INITIAL INTENSITY HAS BEEN INCREASED TO 45 KNOTS 
BASED ON THE TIGHTLY WRAPPED STRUCTURE OBSERVED IN THE SATELLITE 
IMAGERY AND RADAR ANIMATION AND AGREES WITH THE DVORAK INTENSITY 
ESTIMATE FROM PGTW THAT INCREASED TO 45 KNOTS AS WELL. UPPER-LEVEL 
ANALYSIS INDICATES A CONTINUALLY FAVORABLE ENVIRONMENT WITH GOOD 
POLEWARD OUTFLOW AND LOW (10 TO 15 KNOTS) VERTICAL WIND SHEAR (VWS). 
TS 23W IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF THE LOW TO MID-
LEVEL REFLECTION OF THE SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 23W IS FORECAST TO TRACK WEST-NORTHWESTWARD TO WESTWARD 
THROUGH TAU 24 AS IT SWITCHES STEERING INFLUENCES FROM THE CURRENT 
STR TO ANOTHER STR ANCHORED NORTH OF SOUTHEAST ASIA AND THE SOUTH 
CHINA SEA. AS THIS STR ASSUMES STEERING, THE SYSTEM IS EXPECTED TO 
TRACK WEST-SOUTHWESTWARD THROUGH TAU 72. TS 23W IS FORECAST TO 
SLIGHTLY WEAKEN OVER THE NEXT DAY AS IT TRACKS OVER THE PHILIPPINE 
ISLANDS BUT IS EXPECTED TO RE-INTENSIFY AS IT EMERGES OVER THE SULU 
SEA.
   C. IN THE EXTENDED TAUS, TS 23W IS FORECAST TO CONTINUE TO TRACK 
WEST-SOUTHWESTWARD ALONG THE STR. FURTHER INTENSIFICATION WILL BE 
LIMITED DUE TO INCREASING INTERACTION WITH A STRONG NORTHEASTERLY 
SURGE EVENT, WHICH WILL ADVECT COOLER, MORE STABLE AIR INTO THE 
SYSTEM INDUCING A WEAKENING TREND. DYNAMIC MODEL GUIDANCE REMAINS IN 
GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC 
FORECAST TRACK AS SUPPORTED BY THE BULK OF THE DYNAMIC MODEL 
GUIDANCE.//
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