Tropical Storm NOUL Advisory Thu Sep 17

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (NOUL)
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 13W (NOUL), LOCATED APPROXIMATELY 363 NM
EAST-SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD
AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED, WELL-DEFINED LOW-
LEVEL CIRCULATION CENTER (LLCC), WHICH SUPPORTS THE INITIAL POSITION
WITH GOOD CONFIDENCE, WITH LIMITED DEEP CONVECTION OVER THE WESTERN
QUADRANT. A 162228Z AMSU 89GHZ IMAGE REVEALS LIMITED DEEP CONVECTIVE
BANDING OVER THE WESTERN SEMICIRCLE. THE INITIAL INTENSITY REMAINS
ASSESSED AT 45 KNOTS BASED ON THE HIGHER END OF DVORAK ESTIMATES
RANGING FROM T2.5 TO T3.0 (35 TO 45 KNOTS). ADT ESTIMATES ARE HIGHER
AT 3.4-3.5 (ABOUT 55 KNOTS) WITH A 162227Z SATCON ESTIMATE OF 50
KNOTS. A 170047Z ASCAT-A IMAGE INDICATED 40-45 KNOT WINDS OVER THE
WESTERN QUADRANT, WHICH ALSO SUPPORTS THE INITIAL INTENSITY
ESTIMATE. ENVIRONMENTAL ANALYSIS INDICATES PERSISTENT NORTHEASTERLY
VERTICAL WIND SHEAR (VWS) OF 20-25 KNOTS OFFSET BY VIGOROUS
EQUATORWARD OUTFLOW, WARM SST VALUES (31C) AND HIGH OCEAN HEAT
CONTENT VALUES. ANIMATED WATER VAPOR IMAGERY REVEALS WEAK POLEWARD
OUTFLOW RESTRICTED BY CONVERGENT FLOW TO THE NORTH. TS NOUL
CONTINUES TO TRACK ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS NOUL WILL CONTINUE TO TRACK GENERALLY WEST-NORTHWESTWARD
UNDER THE STEERING INFLUENCE OF THE STR THROUGHOUT THE FORECAST
PERIOD. AS IT TRAVERSES OVER THE VERY WARM WATERS OF THE SOUTH CHINA
SEA, IT WILL CONTINUE TO STEADILY INTENSIFY DESPITE CONTINUED
MODERATE TO HIGH (15-25 KTS) VWS AS A RESULT OF THE WARM SSTS AND
STRONG EQUATORWARD OUTFLOW AND REACH A MAXIMUM INTENSITY OF 60 KTS
BY TAU 24. NEAR TAU 30 THE SYSTEM WILL MAKE LANDFALL NEAR HUE,
VIETNAM. AFTER MAKING LANDFALL THE SYSTEM WILL BEGIN TO WEAKEN DUE
TO INTERACTION WITH THE MOUNTAINOUS TERRAIN. AS TS NOUL TRACKS
DEEPER INTO SOUTHEAST ASIA, IT WILL BEGIN TO DISSIPATE OVER LAND AND
SHOULD DISSIPATE BY TAU 48. NUMERICAL MODEL SOLUTIONS ARE IN GOOD
AGREEMENT WITH A 92 NM SPREAD IN SOLUTIONS AT TAU 24, LENDING
OVERALL HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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