Tropical Storm NOUL Advisory Fri Sep 18

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (NOUL) WARNING NR
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 13W (NOUL), LOCATED APPROXIMATELY 272 NM EAST
OF DA NANG, VIETNAM, HAS TRACKED NORTHWESTWARD AT 17 KNOTS (KTS)
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS A FULLY-EXPOSED, WELL-DEFINED LOW LEVEL CIRCULATION
CENTER (LLCC), SUPPORTING THE INITIAL POSITION WITH GOOD CONFIDENCE.
THE MSI SHOWS LIMITED DEEP CONVECTION OVER THE WESTERN QUADRANT OF
THE LLCC. A 170539Z ATMS 88.2 GHZ MICROWAVE IMAGE REVEALS LIMITED
DEEP CONVECTIVE BANDING OFFSET FROM THE LLCC OVER THE WESTERN
SEMICIRCLE. THE INITIAL INTENSITY REMAINS ASSESSED AT 45 KTS BASED
ON THE HIGHER END OF DVORAK ESTIMATES OF T2.5-3.0 (35-45 KTS,
PGTW/RJTD). FURTHERMORE, THE INITIAL INTENSITY IS BASED ON A 170610Z
ADVANCED DVORAK TECHNIQUE ESTIMATE OF T3.4 (ABOUT 55 KTS) AND A
170136Z SATCON ESTIMATE OF 48 KTS. ENVIRONMENTAL ANALYSIS INDICATES
PERSISTENT 20-25 KT NORTHEASTERLY VERTICAL WIND SHEAR (VWS) BEING
OFFSET BY EQUATORWARD OUTFLOW, WARM SST VALUES (30-31 CELSIUS), AND
HIGH OCEAN HEAT CONTENT VALUES, MAINTAINING AN OVERALL MARGINAL
ENVIRONMENT FOR DEVELOPMENT. POLEWARD OUTFLOW IS BEING RESTRICTED BY
CONVERGENT FLOW TO THE NORTH. TS 13W IS TRACKING ALONG THE
SOUTHEASTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) LOCATED TO THE
NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE. ALL WIND RADII HAVE BEEN
UPDATED BASED ON RECENT ASCAT DATA.
   B. FOR THE REMAINDER OF THE FORECAST PERIOD, TS 13W WILL TRACK
WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR. THE WARM
WATERS OF THE SOUTH CHINA SEA WILL ENABLE THE SYSTEM TO SLIGHTLY
INTENSITFY IN THE NEAR TERM DESPITE CONTINUED MODERATE TO HIGH (20-
30 KT) VWS. THIS INTENSIFICATION WILL BE FURTHER SUPPORTED BY
CONTINUED EQUATORWARD OUTFLOW, REACHING A PEAK INTENSITY OF 50 KTS
BY TAU 12. THE SYSTEM IS EXPECTED TO MAINTAIN THIS INTENSITY UNTIL
IT MAKES LANDFALL NEAR HUE, VIETNAM JUST AFTER TAU 24. FOLLOWING
LANDFALL, THE MOUNTAINOUS TERRAIN AND CONTINUED STRONG VWS WILL
STEADILY WEAKEN THE SYSTEM AND FULL DISSIPATION OVER LAND IS
ANTICIPATED BY TAU 48 AS TS 13W TRACKS DEEPER INTO SOUTHEAST ASIA.
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A SPREAD OF 107
NM AT TAU 24. THE GFS AND JGSM SOLUTIONS ACT AS THE SOUTHERLY AND
NORTHERLY OUTLIERS, RESPECTIVELY. OVERALL, THERE IS HIGH CONFIDENCE
IN THE JTWC FORECAST TRACK.//
NNNN
NNNN