Tropical Storm LIONROCK Advisory lun, 29.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (LIONROCK) WARNING NR 45//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   290300Z POSITION NEAR 31.1N 142.1E.
   TYPHOON 12W (LIONROCK), LOCATED APPROXIMATELY 307 NM SOUTH-
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS THE BANDING STRUCTURE BECOMING ELONGATED AND EYE
FEATURE BECOMING CLOUD-FILLED. A 282139Z SSMIS 91GHZ MICROWAVE IMAGE
SHOWS SIGNIFICANT WEAKENING IN THE CONVECTIVE STRUCTURE WITH NOTABLE
WEAKENING ON THE WESTERN EYE WALL AND NORTHWESTERN PERIPHERY. THE
INITIAL POSITION IS BASED ON SATELLITE EYE FIXES FROM PGTW AND RJTD
WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 95 KNOTS
AND IS BASED ON THE DETERIORATING STRUCTURE AND DROPPING DVORAK
ESTIMATES FROM ALL AGENCIES WITH THE CURRENT INTENSITY BEING HELD BY
CONSTRAINTS AT T5.5 TO T6.0 (102 TO 115 KNOTS). UPPER-LEVEL ANALYSIS
INDICATES SIGNIFICANT DISRUPTION TO OUTFLOW OVER THE LAST SIX HOURS.
THE DEEPENING TROUGH TO THE NORTHWEST IS CREATING STRONG
SOUTHWESTERLY FLOW RESTRICTING THE EQUATORWARD CHANNEL. A TUTT CELL
TO THE NORTHEAST IS FURTHER EXACERBATING THE RESTRICTED EXHAUST OVER
THE SYSTEM. CURRENTLY TY 12W IS TRACKING NORTHEASTWARD ALONG THE
EXTENSION OF A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 12W IS EXPECTED TO CONTINUE TO TRACK NORTHEASTWARD UNDER
THE INFLUENCE OF THE NER WHILE UNDERGOING SIGNIFICANT WEAKENING IN
THE NEXT 24 TO 36 HOURS AS IT TRACKS INTO COOLER WATERS AND UPPER-
LEVEL CONDITIONS CONTINUE TO DETERIORATE. BEYOND TAU 24, STEERING
WILL BEGIN TO SHIFT TO A NORTHERN DEEP-LAYERED RIDGE ANCHORED NEAR
THE KURIL ISLANDS AND TURN TY 12W ON A NORTHWESTERLY TRACK INTO THE
DEEPENING TROUGH OVER JAPAN. LANDFALL IS EXPECTED OVER NORTHERN
HONSHU JUST BEFORE TAU 36 WITH THE INTENSITY NEAR 60 KNOTS. TY 12W
IS EXPECTED TO START EXTRATROPICAL TRANSITION AS IT BEGINS TO
INTERACT WITH BAROCLINIC ZONE WITHIN THE TROUGH AROUND THE SAME TIME
IT MAKES LANDFALL. THE MOUNTAINOUS TERRAIN OF NORTHERN HONSHU WILL
SIGNIFICANTLY DISRUPT THE LOW LEVEL WIND FLOW RESULTING IN A
SEVERELY WEAKENED SYSTEM BY TAU 48 AS IT RESURFACES OVER THE SEA OF
JAPAN WITH AN INTENSITY OF APPROXIMATELY 45 KNOTS. TY 12W IS
EXPECTED TO BECOME FULLY EXTRATROPICAL BY TAU 72 AS IT TRACKS INTO
MANCHURIA. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT AND CONTINUES
TO SHOW TIGHTER GROUPING IN THE NORTHWESTERN TURN WITH EACH
SUCCESSIVE RUN OVER THE LAST 18 HOURS. COAMPS-TC IS THE ONLY OUTLIER
OFF TO THE EAST SHOWING A SLIGHTLY WIDER AND SLOWER TURN WHICH
DOESN'T REFLECT THE CURRENT SYNOPTIC SITUATION WELL. THE FORECAST
TRACK IS NOW PLACED CLOSE TO THE MULTI-MODEL CONSENSUS. THERE IS
GOOD CONFIDENCE IN THE FORECAST TRACK, BUT A DEGREE OF UNCERTAINTY
STILL REMAINS AS THE TY 12W BEGINS ACCELERATING INTO THE TROUGH AND
STARTS TRANSITIONING INTO AN EXTRATROPICAL SYSTEM.//
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