Tropical Storm HAGUPIT Advisory Thu Dec 11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (HAGUPIT) WARNING
NR 42//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 22W (HAGUPIT), LOCATED APPROXIMATELY 354 NM
EAST-NORTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WEST-
SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS PERSISTENT DEEP
CONVECTION SHEARED TO THE NORTHEAST OVER A PARTIALLY-EXPOSED LOW-
LEVEL CIRCULATION CENTER. AN 110155Z METOP-B MICROWAVE IMAGE REVEALS
SHALLOW CONVECTIVE BANDING WRAPPING INTO THE CENTER. AN 110156Z
ASCAT PASS PARTIALLY SHOWS 3O KNOT WINDS ON THE NORTHWESTERN
QUADRANT. THE CURRENT POSITION IS BASED ON THE MSI AND THE PGTW FIX
WITH GOOD CONFIDENCE. THE INITIAL INTENSITY REMAINS AT 35 KNOTS
BASED ON AN OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM
ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS
LOCATED IN AN AREA OF MARGINAL VERTICAL WIND SHEAR (VWS) OFFSET BY
GOOD POLEWARD OUTFLOW. TS 22W IS CURRENTLY TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 22W IS EXPECTED TO MAINTAIN A WEST-SOUTHWESTWARD TRAJECTORY
THROUGH THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF LOW-
LEVEL NORTHEASTERLY FLOW. TS HAGUPIT WILL CONTINUE TO WEAKEN IN
RESPONSE TO MORE STABLE AIR AND CONTINUED VWS ASSOCIATED WITH THE
NORTHEASTERLY SURGE. THE SYSTEM IS FORECAST TO MAKE LANDFALL OVER
SOUTHERN VIETNAM BY TAU 18 AND SHOULD DISSIPATE OVER LAND BY THE END
OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT
AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST WHICH
IS POSITIONED CLOSE TO MULTI-MODEL CONSENSUS.//
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