Tropical Storm HALONG Advisory mer, 06.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HALONG) WARNING NR 35//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 11W (HALONG), LOCATED APPROXIMATELY 284 NM SOUTH-
SOUTHEAST OF KADENA AB, HAS TRACKED NORTH-NORTHEASTWARD AT 06 KNOTS
OVER THE PAST SIX HOURS. THE ANIMATED MULTISPECTRAL SATELLITE
IMAGERY LOOP CONTINUES TO SHOW A SLIGHT DEGRADATION OF THE DEEP
CONVECTION OVER THE NORTHERN PORTION OF THE LOW LEVEL CIRCULATION
CENTER (LLCC), CONFIRMED BY A PARTIAL 051942Z SSMIS PASS. TY HALONG
CONTINUES TO TRACK SLIGHTLY NORTH-NORTHEASTWARD, DRIVEN BY A
RETROGRADING TUTT CELL TO THE NORTHEAST. ADDITIONALLY, THE TRACK
SPEED HAS SLOWED SLIGHTLY DUE TO THE WEAKER INFLUENCE OF THE
SUBTROPICAL RIDGE (STR), CURRENTLY EAST OF THE STORM, BECAUSE OF THE
INFLUENCE OF THE AFOREMENTIONED TUTT. THE SUBSIDENCE ASSOCIATED WITH
THE TUTT ALONG WITH MODERATE (20 KNOTS) VERTICAL WIND SHEAR (VWS) TO
THE NORTHEAST OF THE SYSTEM ARE OFFSET BY THE GOOD EQUATORWARD
OUTFLOW. THIS, IN ADDITION TO THE FAIRLY GOOD AGREEMENT IN THE
DVORAK CURRENT INTENSITY FROM RJTD AND PTGW, LEADS TO JTWC
MAINTAINING THE INITIAL INTENSITY OF 80 KNOTS.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE PREVIOUS PROGNOSTIC
REASONING.
   B. THE SYSTEM WILL CONTINUE TO TRACK NORTH-NORTHEASTWARD THROUGH
TAU 24 AS THE TUTT TO THE NORTHEAST CONTINUES TO PULL THE SYSTEM
SLIGHTLY TO THE EAST. BEYOND TAU 36, THE TUTT CELL TRACKS NORTHEAST
AHEAD OF THE STORM AND BECOMES ABSORBED IN THE WESTERLIES. THE STR
TO THE EAST OF TY 11W WILL REORIENT SLIGHTLY AS THE TUTT CELL
RETROGRADES TO THE NORTH AND BECOME THE MAIN STEERING INFLUENCE OF
THE SYSTEM. TAU 48 AND BEYOND, THERE CONTINUES TO BE SOME
DISAGREEMENT IN MODELED FORECAST TRACK, WITH JENI AND NAVGEM
CONTINUING TO DRIVE THE SYSTEM SLIGHTLY MORE TO THE WEST DUE TO A
WEAK STEERING ENVIRONMENT AS THEY FAVOR A BUILDING OF A STR WEST OF
THE SYSTEM, OVER EASTERN CHINA AND INTO THE YELLOW SEA. HOWEVER,
NAVGEM HAS SLOWLY BACKED DOWN ON THE STRENGTH OF THAT STR. GFS
CONTINUES TO BE THE FAVORED MODEL FOR BOTH TRACK AND SPEED DUE THE
REBUILDING OF THE STR EAST OF THE SYSTEM. EXPECT THAT THE TRACK
SPEED OF THE STORM TO MAINTAIN THROUGH TAU 72 AS THE STR WILL DRIVE
THE STORM SLIGHTLY TO THE NORTHWEST BEFORE ROUNDING THE STR. THERE
IS STILL SIGNIFICANT AMBIGUITY IN THE UPPER LEVEL ANALYSIS WITH
REGARD TO THE DRIVING FACTOR UP TO TAU 72. REGARDLESS, AS THE SYSTEM
BEGINS TO ROUND THE STR TO THE EAST FROM TAU 48 TO 72, EXPECT THE
SYSTEM TO BEGIN EXTRATROPICAL TRANSITION AND WEAKEN.
   C. HALONG WILL MAKE LANDFALL IN SOUTHERN JAPAN AFTER TAU 72 AS
THE SYSTEM STARTS TO BE ABSORBED BY THE MID-LATITUDE WESTERLIES. TS
11W WILL SPEED UP AND CONTINUE TO WEAKEN WITH THE VWS TO INCREASE
AND TOPOGRAPHICAL INFLUENCE OF THE MOUNTAINOUS AREAS OF SHIKOKU AND
WESTERN HONSHU WEAKEN THE SYSTEM. EXPECT COMPLETION OF EXTRATROPICAL
TRANSITION AFTER THE SYSTEM TRACKS ACROSS SOUTHERN JAPAN INTO THE
SEA OF JAPAN. WHILE THE MODELS ARE IN FAIRLY TIGHT AGREEMENT OVER
THE NEXT 48 HOURS, THE BIFURCATION OF THE MODELS IN THE LATER TAUS
AND THE COMPLEX UPPER-LEVEL ENVIRONMENT LEADS TO AN OVERALL LOW
CONFIDENCE IN JTWC'S FORECAST TRACK.//
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