Tropical Storm DUJUAN Advisory 26 Σεπ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (DUJUAN) WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 21W (DUJUAN), LOCATED APPROXIMATELY 417 NM SOUTH-
SOUTHEAST OF KADENA AB, HAS TRACKED NORTH-NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED ENHANCED IR IMAGERY
CONTINUES TO SHOW TIGHTLY-CURVED BANDS WRAPPING INTO A LARGE 35-NM
DIAMETER EYE, WHICH SUPPORTS THE CURRENT POSITION WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 80 KNOTS IS BASED ON THE
CURRENT STRUCTURE AND AN OVERALL ASSESSMENT OF DVORAK INTENSITY
ESTIMATES FROM ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS
INDICATES TY 21W REMAINS IN A FAVORABLE ENVIRONMENT WITH LOW TO
MODERATE (10 TO 20 KNOT) VWS BEING OFFSET BY RADIAL OUTFLOW, AS
EVIDENT ON THE WATER VAPOR IMAGERY, DESPITE SOME SLIGHT DRY AIR
ENTRAINMENT VISIBLE ON THE NORTHEAST QUADRANT. ADDITIONALLY, THE
SHORTWAVE TROUGH PREVIOUSLY FORECAST TO CAUSE A WEAKNESS IN THE
RIDGE OVER THE EAST CHINA SEA HAS FAILED TO MATERIALIZE
SIGNIFICANTLY. TY DUJUAN IS TRACKING SLOWLY ALONG THE SOUTHWESTERN
PERIPHERY OF A DEEP LAYERED STR.
3. FORECAST REASONING.
   A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY DUJUAN WILL MAINTAIN A NORTHWESTWARD TRACK THROUGH THE END
OF THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE STR. DUE
TO PERSISTENT FAVORABLE ENVIRONMENTAL CHARACTERISTICS TO INCLUDE LOW
VWS, GOOD OHC AND GOOD OUTFLOW ALOFT, EXPECT CONTINUED
INTENSIFICATION THROUGH TAU 36 AT A CLIMATOLOGICAL RATE WITH A PEAK
OF 115 KNOTS. HOWEVER, BEYOND TAU 48, EXPECT TY DUJUAN TO BEGIN TO
WEAKEN DUE TO LOWER OHC, DUE TO THE SHALLOW NATURE OF THE EAST CHINA
SEA, AND LAND INTERACTION WITH TAIWAN. EXPECT TY 21W TO MAKE
LANDFALL NEAR TAIPEI BY TAU 72.
   C. IN THE EXTENDED FORECAST, TY 21W WILL DISSIPATE SLIGHTLY AS IT
TRACKS OVER THE MOUNTAINS OF TAIWAN AND INTO THE TAIWAN STRAIT.
MAKING LANDFALL IN CHINA PRIOR TO TAU 96, EXPECT CONTINUED
DISSIPATION OF THE SYSTEM DUE TO TERRAIN FRICTIONAL FORCES THROUGH
THE END OF THE FORECAST PERIOD. AVAILABLE MODEL GUIDANCE HAS COME
INTO BETTER AGREEMENT WITH THE GFS SUITE OF MODELS TRACKING MORE TO
THE WEST, VICE RECURVING INTO THE RYUKYU ISLANDS. AS SUCH, THERE IS
HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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