Tropical Storm HALONG Advisory Mon Aug 04

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 11W (HALONG) WARNING NR
24//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 11W (HALONG), LOCATED APPROXIMATELY 710 NM
SOUTH-SOUTHEAST OF KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A SYMMETRIC EYEWALL WITH A 26 NM ROUND EYE,
THEREFORE, THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION. A
030536Z SSMI IMAGE DEPICTS CONCENTRIC EYEWALLS AND RECENT MICROWAVE
IMAGERY INDICATES AN INCIPIENT EYEWALL REPLACEMENT CYCLE (ERC)
ALTHOUGH ONLY SLIGHT WEAKENING WAS INDICATED IN INFRARED SATELLITE
IMAGERY. DVORAK FINAL T ESTIMATES DECREASED TO T6.5 (127 KNOTS),
HOWEVER, THE INITIAL INTENSITY REMAINS ASSESSED AT 140 KNOTS BASED
ON DVORAK CURRENT INTENSITY ESTIMATES OF T7.0 (140 KNOTS). AS
INDICATED IN ANIMATED WATER VAPOR IMAGERY, OUTFLOW HAS REMAINED
VIGOROUS, ESPECIALLY EQUATORWARD OUTFLOW, DESPITE SOME PRESSURE ON
THE NORTHERN PERIPHERY OF THE SYSTEM ASSOCIATED WITH UPPER-LEVEL
RIDGING SOUTH OF JAPAN. RECENT 500 MB ANALYSES INDICATE A WEAKENING,
NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED SOUTH OF
CENTRAL JAPAN WITH PERSISTENT SOUTHWESTERLY FLOW FROM TAIWAN TO THE
RYUKYU ISLANDS. STY 11W IS CURRENTLY TRACKING WEST-NORTHWESTWARD
ALONG THE SOUTHWESTERN PERIPHERY OF THIS STR.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY.
   B. THIS SYNOPTIC STEERING ENVIRONMENT IS FORECAST TO MAINTAIN FOR
THE NEXT THREE DAYS, DUE TO THE POSITION OF TD 12W, WHICH SHOULD
ALLOW STY 11W TO TRACK NORTHWARD THROUGH TAU 72. WITH THE EXCEPTION
OF GFDN AND COAMPS-TC, WHICH TRACK THE SYSTEM ERRONEOUSLY NORTH-
NORTHEASTWARD INTO THE STR, THE BULK OF THE DYNAMIC MODEL GUIDANCE
IS IN TIGHT AGREEMENT THROUGH TAU 72 WITH A 105-NM SPREAD IN
SOLUTIONS AT TAU 72, THEREFORE, THE JTWC FORECAST IS POSITIONED
CLOSE TO THE MULTI-MODEL CONSENSUS. STY 11W IS FORECAST TO MAINTAIN
SUPER TYPHOON STRENGTH THROUGH TAU 12 THEN WEAKEN DUE TO THE ERC.
   C. IN THE EXTENDED TAUS, THERE IS INCREASING UNCERTAINTY IN THE
TRACK WITH GREATER SPREAD IN THE SOLUTIONS. AN APPROACHING
MIDLATITUDE SHORTWAVE TROUGH IS FORECAST TO DIG OVER THE KOREAN
PENINSULA AND WESTERN JAPAN, CREATING A BREAK IN THE STR, HOWEVER,
THE DYNAMIC MODELS BUILD THE STR AHEAD OF THE TROUGH TO VARYING
DEGREES. THE MOST LIKELY SCENARIO IS THAT THE SYSTEM TRACKS NORTH-
NORTHWESTWARD AS A MINOR EXTENSION OF THE STR BUILDS TEMPORARILY
NEAR KYUSHU, JAPAN. IN ADDITION TO COAMPS-TC AND GFDN, GFS AND THE
GFS ENSEMBLE (GEFS) SHOW A SHARP NORTHEASTWARD TURN TOWARD SHIKOKU
AND CENTRAL JAPAN, HOWEVER, GFS APPEARS TO TRACK THE SYSTEM INTO THE
STR, WHICH SEEMS UNLIKELY. THEREFORE, THE JTWC FORECAST CONTINUES TO
FAVOR THE ECMWF AND JGSM SOLUTIONS AND IS POSITIONED WEST OF THE
MULTI-MODEL CONSENSUS AFTER TAU 72 TO OFFSET GFS, COAMPS-TC AND
GFDN. 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.//
NNNN
NNNN