Tropical Storm SAUDEL Advisory do, 22-10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (SAUDEL) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 19W (SAUDEL), LOCATED APPROXIMATELY 336 NM SOUTH-
SOUTHEAST OF HONG KONG, HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
THE CENTRAL CONVECTION HAS BECOME MORE COMPACT AND SYMMETRICAL AS
RAIN BANDS WRAPPED TIGHTER INTO THE LLC. THE INITIAL POSITION IS
PLACED WITH GOOD CONFIDENCE BASED ON AN EVOLVING MICROWAVE EYE IN THE
212308Z SSMIS PASS. THE INITIAL INTENSITY OF 65KTS IS BASED ON THE
DVORAK ESTIMATES OF T4.0/65KTS FROM PGTW, KNES, AND RJTD. THE
ENVIRONMENT REMAINS FAVORABLE FOR CONTINUED DEVELOPMENT WITH LOW
(10-15KT) VERTICAL WIND SHEAR (VWS), WARM (29-30C) SEA SURFACE
TEMPERATURES (SST) IN THE SOUTH CHINA SEA, AND RADIAL UPPER-LEVEL
OUTFLOW. A SHORTWAVE TROUGH DIGGING INTO TAIWAN HAS WEAKENED THE
STEERING SUBTROPICAL RIDGE (STR), PULLING THE CYCLONE POLEWARD INTO
THE COL FORMED BETWEEN THE SPLIT STRS - ONE TO THE WEST AND ONE TO
THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. OVER THE NEXT 24-36HRS, TY 19W WILL TRACK VERY SLOWLY AND/OR
BECOME QUASI-STATIONARY IN THE COL. AFTERWARD, THE STR TO THE EAST
WILL BUILD AND EXTEND WESTWARD, BECOME THE DOMINANT STEERING
MECHANISM, AND SLOWLY DRIVE THE CYCLONE WESTWARD TOWARD CENTRAL
VIETNAM. BY TAU 72, TY 19W WILL HAVE REACHED A POINT APPROXIMATELY
65NM SOUTH-SOUTHWEST OF HAINAN, CHINA. THE FAVORABLE ENVIRONMENT WILL
FUEL INTENSIFICATION TO A PEAK OF 75KTS BY TAU 24; AFTERWARD, COOLING
SST DUE TO UPWELLING IN THE COL AND INCREASING VWS AS THE CYCLONE
TRACKS WESTWARD WILL GRADUALLY WEAKEN THE SYSTEM AND BY TAU 72, WILL
BE DOWN TO 50KTS. NUMERICAL MODELS ARE IN AGREEMENT AS FAR AS
RETAINING THE SYSTEM IN THE COL FOR A PERIOD OF TIME. HOWEVER, THEY
OFFER VARYING SOLUTIONS AS TO WHEN THE CYCLONE WILL EXIT OUT OF THE
COL WITH NVGM TAKING A MORE POLEWARD TRACK AND AFUM, UEMN, AND EGRR
TAKING A MORE DELAYED LOOPING MOTION. IN VIEW OF THESE, THERE IS LOW
CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST.
   C. BEYOND TAU 72, TY SAUDEL WILL TRACK MORE WEST-SOUTHWESTWARD AS
THE STR TO THE WEST ASSUMES STEERING, MAKE LANDFALL JUST NORTH OF
HUE, VIETNAM, BY TAU 78, THEN DRAG ACROSS LAOS AND INTO THAILAND BY
TAU 120. THE RUGGED TERRAIN WILL PRIMARILY ERODE THE SYSTEM TO
DISSIPATION BY TAU 120. THERE IS ALSO LOW CONFIDENCE IN THE EXTENDED
PORTION OF THE JTWC FORECAST TRACK BECAUSE IT IS DEPENDENT OF THE
NEAR-TO-MID TERM PORTION OF THE FORECAST TRACK.//
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