Tropical Storm HALONG Advisory sáb, 09-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (HALONG) WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 24W (HALONG), LOCATED APPROXIMATELY 293 NM NORTH-
NORTHEAST OF MINAMI TORI SHIMA, JAPAN, HAS TRACKED NORTHEASTWARD AT
24 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY AND A 080444Z SSMIS 91GHZ IMAGE DEPICT A LARGE AREA OF DEEP
CONVECTION SURROUNDING AN APPARENT MICROWAVE EYE FEATURE, LENDING
GOOD CONFIDENCE TO THE INITIAL POSITION. UPPER-LEVEL ANALYSIS
REVEALS A MARGINALLY UNFAVORABLE ENVIRONMENT WITH MODERATE (20 TO 25
KNOTS) WESTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY CONTINUED,
STRONG POLEWARD OUTFLOW. THE CURRENT INTENSITY IS ASSESSED AT 75
KNOTS BASED ON A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF 4.5 (77
KNOTS). TY 24W IS TRACKING WITHIN THE MIDLATITUDE WESTERLY FLOW
ALONG THE NORTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE
(STR).
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY HALONG WILL CONTINUE TO TRACK NORTHEASTWARD AND GRADUALLY
TURN EAST-NORTHEASTWARD BY TAU 12. THE ENVIRONMENT WILL BECOME MORE
UNFAVORABLE WITH INCREASING VWS AND COOLING SSTS, LEADING TO RAPID
WEAKENING. EXTRA-TROPICAL TRANSITION (ETT) WILL BEGIN AT TAU 12 AS
TY 24W BEGINS TO INTERACT WITH THE BAROCLINIC ZONE. BY TAU 36 THE
SYSTEM WILL COMPLETE ETT AND WEAKEN TO 35 KNOTS. NUMERICAL MODELS
ARE IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK.//
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