Tropical Storm HALONG Advisory dom, 03-08

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 11W (HALONG) WARNING NR
23//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 11W (HALONG), LOCATED APPROXIMATELY 759 NM
SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WESTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS AN INTENSE SYSTEM AS A THICK RING OF DEEP CONVECTION
HAS PERSISTED AROUND A SHARPLY 28-NM EYE. THE MSI ALSO SHOWS A
SLIGHT THINNING OF THE CONVECTION ALONG THE NORTHERN QUADRANT OF THE
SYSTEM. A SERIES OF MICROWAVE IMAGERY INCLUDING A 022249Z SSMIS
MICROWAVE IMAGERY REVEAL THE DEEP CONVECTION WITHIN THE EYEWALL HAS
SLIGHTLY DEGRADED IN VARIOUS LOCATIONS, AND COULD BE THE RESULT OF
AN EYEWALL REPLACEMENT CYCLE (ERC). THE CURRENT POSITION IS BASED ON
THE EYE FEATURE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 140
KNOTS IS BASED ON CONSISTENT DVORAK CURRENT INTENSITY ESTIMATES FROM
PGTW AND KNES. UPPER-LEVEL ANALYSIS INDICATES A POINT SOURCE
ANTICYCLONE OVER THE SYSTEM PROVIDING EXCELLENT OUTFLOW OFFSETTING
THE MODERATE NORTHEASTERLY VERTICAL WIND SHEAR (VWS). STY 11W IS
CURRENTLY TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. STY 11W IS EXPECTED TO TRACK WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR OVER THE NEXT 24. BETWEEN TAU 36 AND
48, AN UPPER-LEVEL TROUGH PASSING OVER THE KOREAN PENINSULA AND
WESTERN JAPAN CREATES A BREAK IN THE STR, CAUSING STY HALONG TO TURN
NORTH-NORTHWESTWARD. IN ADDITION TO WARM SEA SURFACE TEMPERATURES,
FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST ALLOWING STY 11W TO
MAINTAIN SUPER TYPHOON STRENGTH OVER THE NEXT 24 HOURS AND THEN
WEAKEN SLIGHTLY AS IT TRACKS INTO INCREASING NORTHERLY VWS.
   C. AFTER TAU 72, STY HALONG IS FORECAST TO TRACK NORTHWARD ALONG
THE WESTERN PERIPHERY OF THE STR THROUGH THE REMAINDER OF THE
FORECAST PERIOD. DUE TO THE UNCERTAINTY IN TIMING OF THE POLEWARD
TURN NEAR TAU 24 AND THE DEPICTION OF THE TROUGH AND STR IN THE
EXTENDED TAUS, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST,
WHICH IS POSITIONED CLOSE TO MULTI-MODEL CONSENSUS.//
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