Tropical Storm HALONG Advisory Wed Aug 06

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HALONG) WARNING NR 37//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 11W (HALONG), LOCATED APPROXIMATELY 250 NM SOUTHEAST OF
KADENA AB, OKINAWA, HAS TRACKED NORTHEASTWARD AT 07 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS
THE CENTRAL STRUCTURE OF THE SYSTEM HAS STRUGGLED TO MAINTAIN AS THE
EYEWALL HAS OPENED ALONG THE NORTHERN HALF OF THE LOW LEVEL
CIRCULATION CENTER (LLCC). BASED ON THE DVORAK ENHANCEMENT OF THE
INFRARED SATELLITE IMAGERY, THERE HAS BE A SLIGHT DECREASE IN DEEP
CENTRAL CONVECTION, BUT GIVE THE DVORAK ESTIMATES FROM PGTW AND RJTD,
THE CURRENT INTENSITY HAS BEEN MAINTAINED AT 85 KNOTS. ANIMATED WATER
VAPOR IMAGERY SHOWS THE TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT)
CELL TO THE NORTHEAST OF THE SYSTEM CONTINUES TO RETROGRADE NORTHWARD
OVER THE PAST SIX HOURS AND HAS BEEN HELPING TO ENHANCE THE POLEWARD
OUTFLOW FOR TY 11W. UPPER LEVEL ANALYSIS INDICATES A WEAKLY DEFINED
POINT SOURCE ANTICYCLONE OVER TY 11W IS HELPING TO MAINTAIN THE
CURRENT INTENSITY. TY 11W HAS SHOWN SOME INDICATIONS OF AN EASTWARD
WOBBLE OVER THE PAST FEW HOURS AND HAS SHIFTED TO A MORE NORTHEAST-
WARD TRACK AROUND A DEEP LAYERED SUBTROPICAL RIDGE (STR) LOCATED TO
THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE PREVIOUS PROGNOSTIC
REASONING.
   B. THE SYSTEM WILL START TO TRACK MORE NORTHWARD IN THE NEXT 12
HOURS AS THE STR TO THE EAST REORIENTS WITH THE RETROGRADING TUTT
CELL TO THE NORTHEAST. BY TAU 48 TY 11W WILL BE LOCATED ON THE NORTH-
WESTERN QUADRANT OF THE STR, SHIFTING TO A NORTHEASTWARD TRACK
THEREAFTER. IMPROVING POLEWARD OUTFLOW, AS TY 11W TAPS INTO THE MID-
LATITUDE WESTERLIES, OVER THE NEXT 36 HOURS WILL ALLOW FOR A BRIEF
PERIOD OF INTENSIFICATION. BEYOND TAU 36 THE WESTERLIES WILL BEGIN TO
IMPINGE ON THE NORTHWESTERN QUADRANT OF THE SYSTEM, LEADING TO A SLOW
WEAKENING TREND THROUGH TAU 72 AND THE START OF THE EXTRA-TROPICAL
TRANSITION (ETT) PROCESS.
   C. TY HALONG WILL MAKE LANDFALL IN SOUTHERN JAPAN SLIGHTLY AFTER
TAU 72 AS THE SYSTEM STARTS TO BECOME FURTHER ENTRENCHED WITHIN THE
MID-LATITUDE WESTERLIES. THE LLCC WILL SPEED UP AND CONTINUE TO
WEAKEN
WITH INCREASING VERTICAL WIND SHEAR AND TOPOGRAPHICAL IMPACTS FROM
THE MOUNTAINOUS AREAS OF SHIKOKU AND WESTERN HONSHU. EXPECT ETT TO
BE COMPLETED BY TAU 120 AS THE SYSTEM MOVES INTO THE NORTHEASTERN
REGION OF THE SEA OF JAPAN AND IS FULLY ABSORBED WITHIN THE MID-
LATITUDE WESTERLIES. MODEL GUIDANCE REMAINS WIDELY SPREAD PAST TAU
24, WITH A LARGE VARIATION IN THE STEERING FLOW THROUGH TAU 48. THIS
FORECAST FAVORS THE AVNO AND ECMF SOLUTIONS BUT BASED ON LARGE
VARIATION IN THE STEERING PATTERN AND COMPLEX UPPER-LEVEL ENVIRON-
MENT THE CONFIDENCE IN THE FORECAST TRACK REMAINS LOW.//
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