Tropical Storm DUJUAN Advisory mer, 23.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (DUJUAN) WARNING NR
06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 21W (DUJUAN), LOCATED APPROXIMATELY 503 NM
SOUTH-SOUTHWEST OF IWO TO, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MSI DEPICTS PERSISTENT DEEP CONVECTION TO
THE WEST OF A PARTIALLY EXPOSED LLCC. THE INITIAL POSITION IS BASED
ON THE PARTIALLY EXPOSED LLCC IN THE MSI ANIMATION AND A 222058Z
CORIOLIS IMAGE WITH MODERATE CONFIDENCE. THE CURRENT INTENSITY HAS
BEEN INCREASED TO 40 KNOTS BASED ON A 222100Z WINDSAT IMAGE WITH 40
KNOT WIND BARDS AS WELL AS A SATCON INTENSITY ESTIMATE OF 43 KNOTS.
UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH 10 TO 20
KNOTS OF EASTERLY VWS BEING PARTIALLY OFFSET BY DIVERGENCE ALOFT. TS
21W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP LAYERED STR.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS DUJUAN WILL CONTINUE TO TRACK WEST-NORTHWESTWARD OVER THE
NEXT 36 HOURS AS THE STR REMAINS TO THE NORTH OF THE SYSTEM. DURING
THIS TIMEFRAME, EXPECT MARGINAL INTENSIFICATION DUE TO MODERATE VWS
AFFECTING THE SYSTEM. BEYOND TAU 36, EXPECT A SHORTWAVE MID-LATITUDE
TROUGH TO CREATE A SMALL BREAK IN THE STR, ALLOWING A STRONGER TS
21W TO GAIN A MORE POLEWARD TRAJECTORY. ADDITIONALLY, EXPECT
IMPROVED OUTFLOW TO ALLOW FOR NEAR RAPID INTENSIFICATION FOR THE
SYSTEM THROUGH TAU 72, NEARING 100 KNOTS.
   C. IN THE EXTENDED FORECAST, TS 21W WILL CONTINUE TO INTENSIFY
DUE TO FAVORABLE ENVIRONMENTAL CONDITIONS, ALBEIT AT A SLOWER RATE
THAN PREVIOUSLY. DYNAMIC MODEL GUIDANCE CONTINUES TO DISPLAY A WIDE
ARRAY OF SOLUTIONS REGARDING THE TIMING AND EXTENT OF THE RECURVE,
WITH ECMWF NOW DEPICTING A SLIGHTLY LATER RE-CURVE, COMING MORE IN
ALIGNMENT WITH GFS AND NAVGEM. DUE TO THE CONTINUED WIDE SPREAD IN
DYNAMIC MODEL GUIDANCE, THERE REMAINS LOW CONFIDENCE IN THE JTWC
TRACK FORECAST.//
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