Tropical Storm HALONG Advisory 07 Αυγ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HALONG) WARNING NR 38//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 11W (HALONG), LOCATED APPROXIMATELY 239 NM SOUTHEAST OF
KADENA AB, OKINAWA, JAPAN HAS TRACKED NORTHEASTWARD AT 07 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS A 9-NM DIAMETER EYE WITH INTENSIVE CONVECTIVE
BANDING OVER THE SOUTHERN PERIPHERY TIGHTLY-WRAPPED INTO A LOW-LEVEL
CIRCULATION CENTER. A 061803Z NOAA-19 MICROWAVE IMAGE ALSO REVEALS
THE DEEP CONVECTION TIGHTLY-WRAPPING TOWARDS A WELL-DEFINED
MICROWAVE EYE. THE CURRENT POSITION IS BASED ON THE EIR ANIMATION
AND AFOREMENTIONED MICROWAVE IMAGE WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY OF 90 KNOTS IS BASED ON CONSISTENT DVORAK INTENSITY
ESTIMATES FROM ALL REPORTING AGENCIES. ANIMATED WATER VAPOR IMAGERY
SHOWS A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE
NORTHEAST OF THE SYSTEM ENHANCING THE POLEWARD OUTFLOW,
WHILE A SMALLER TUTT CELL OVER THE NORTHWEST QUADRANT THINS THE
CONVECTION. HOWEVER, UPPER LEVEL ANALYSIS INDICATES TY 11W REMAINS
IN FAVORABLE ENVIRONMENT WITH LOW TO MODERATE VERTICAL WIND SHEAR
(VWS) AND EXCELLENT EQUATORWARD OUTFLOW. TY HALONG IS CURRENTLY
TRACKING NORTHWESTWARD UNDER THE STEERING INFLUENCE OF 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. TY 11 IS EXPECTED TO TRACK NORTHWARD OVER THE NEXT 06 TO 12
HOURS AS THE STR TO THE EAST REORIENTS WITH THE RETROGRADING TUTT
CELL TO THE NORTHEAST. BY TAU 48, THE SYSTEM WILL BE LOCATED ON THE
NORTH-WESTERN QUADRANT OF THE STR, SHIFTING TO A NORTHEASTWARD TRACK
THEREAFTER. FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST, ALLOWING
TY 11W TO MAINTAIN ITS INTENSITY THROUGH TAU 36. BY TAU 48, THE
WESTERLIES WILL BEGIN TO IMPINGE ON THE NORTHWESTERN QUADRANT OF THE
SYSTEM, LEADING TO A SLOW WEAKENING TREND AND THE START OF THE EXTRA-
TROPICAL TRANSITION (ETT) PROCESS.
   C. TY HALONG WILL MAKE LANDFALL INTO SHIKOKU, JAPAN SHORTLY AFTER
TAU 72 AS THE SYSTEM STARTS TO BECOME FURTHER ENTRENCHED WITHIN THE
MID-LATITUDE WESTERLIES. THE COMBINED EFFECTS OF INCREASING VWS AND
FRICTIONAL EFFECTS WILL FURTHER WEAKEN THE SYSTEM. TY 11 IS EXPECTED
TO COMPLETE ETT 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. AVAILABLE MODEL GUIDANCE IS IN BETTER AGREEMENT
IN THE NEAR TERM AND DIVERGES AFTER TAU 48. DUE TO VARIATIONS IN THE
STEERING PATTERN AND COMPLEX UPPER-LEVEL ENVIRONMENT IN THE EXTENDED
TAUS, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST.//
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