Tropical Storm HALONG Advisory 03 Αυγ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 11W (HALONG) WARNING NR
22//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 11W (HALONG), LOCATED APPROXIMATELY 783 NM
SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WEST-
NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
SATELLITE IMAGERY DEPICTS THE SYSTEM HAS MAINTAINED A SYMMETRICAL 25-
NM EYE SURROUNDED BY A WELL-DEFINED DEEP CONVECTIVE EYEWALL. THE
CURRENT POSITION IS BASED ON THIS EYE FEATURE WITH WITH HIGH
CONFIDENCE. A 021825Z SSMI IMAGE DEPICTS 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
INTENSITY IS ASSESSED AT 140 KNOTS 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 WEST-NORTHWESTWARD
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 EXPECT TO CONTINUE TRACKING WEST-NORTHWESTWARD
UNDER THE STEERING INFLUENCE OF THE STR OVER THE NEXT 24 TO 36
HOURS. BETWEEN TAU 36 AND 48, A MIGRATORY UPPER-LEVEL TROUGH LOCATED
TO THE NORTHEAST OF NORTHERN JAPAN IS FORECAST TO EXTEND
SOUTHWESTWARD, MODIFYING THE STR AND CAUSING TY 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 THROUGH TAU 24 AND THEN WEAKEN
SLIGHTLY AS IT TRACKS INTO INCREASING NORTHERLY VWS.
   C. AFTER TAU 72, THE STR IS EXPECTED TO REORIENT TO THE EAST OF
STY 11W AND WILL ASSUME THE STEERING PATTERN, PERMITTING TY HALONG
TO CONTINUE TRACKING 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 36 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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