Tropical Storm LAN Advisory ср, 18.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (LAN)
WARNING NR 10//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 25W (LAN), LOCATED APPROXIMATELY 212 NM
NORTHWEST OF KAYANGEL, HAS TRACKED NORTH-NORTHEASTWARD AT 04 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY AND RECENT MICROWAVE IMAGERY DEPICT A CONSOLIDATING LOW-
LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED DEEP CONVECTIVE
BANDING WRAPPING INTO A DEFINED CENTER. THE INITIAL INTENSITY IS
ASSESSED AT 60 KNOTS BASED ON AN AVERAGE OF DVORAK INTENSITY
ESTIMATES RANGING FROM T3.5 (55 KNOTS) TO T4.0 (65 KNOTS). UPPER-
LEVEL ANALYSIS SHOWS AN EXCELLENT ENVIRONMENT WITH LOW VERTICAL WIND
SHEAR, STRONG POLEWARD OUTFLOW ENHANCED BY THE TUTT, WARM SST (30C)
AND HIGH OCEAN HEAT CONTENT VALUES. AFTER A BRIEF PERIOD OF QUASI-
STATIONARY MOTION ASSOCIATED WITH THE WEAKENING SUBTROPICAL RIDGE TO
THE NORTH, TS 25W IS TRACKING SLOWLY NORTHWARD TO NORTH-
NORTHEASTWARD UNDER THE STEERING INFLUENCE OF THE BUILDING STEERING
RIDGE TO THE SOUTHEAST AND EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. THE 34-KNOT WIND RADII HAVE BEEN
ADJUSTED LARGER BASED ON A DETAILED ANALYSIS OF A RECENT ASCAT IMAGE
SHOWING EXTENSIVE GALE-FORCE WINDS.
   B. TS 25W IS FORECAST TO TRACK NORTHWARD UNDER THE STEERING
INFLUENCE OF THE BUILDING SUBTROPICAL RIDGE TO THE EAST. DESPITE THE
COMPLEX, EVOLVING SYNOPTIC STEERING PATTERN, DYNAMIC MODEL GUIDANCE
REMAINS IN TIGHT AGREEMENT WITH MINOR DIFFERENCES IN TRACK SPEED. TS
LAN IS FORECAST TO INTENSIFY STEADILY THROUGH TAU 72 TO A PEAK
INTENSITY OF 130 KNOTS DUE TO THE VERY FAVORABLE CONDITIONS.
   C. IN THE EXTENDED PERIOD, TS 25W WILL WEAKEN SLIGHTLY AS THE
SYSTEM BEGINS EXTRA-TROPICAL TRANSITION (ETT) AND INTERACTS WITH
UPPER-LEVEL WESTERLIES. TS 25W WILL REMAIN A VERY LARGE SYSTEM WITH
EXTENSIVE GALE-FORCE WINDS, ENHANCED BY A COLD SURGE OVER THE RYUKYU
ISLANDS AND A STRONG BAROCLINIC SYSTEM OVER JAPAN. THE SYSTEM WILL
COMPLETE ETT JUST PRIOR TO MAKING LANDFALL OVER HONSHU BUT WILL
REMAIN A STRONG TYPHOON STRENGTH EXTRA-TROPICAL LOW. OVERALL, THERE
IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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