Tropical Storm LAN Advisory 22 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 25W (LAN) WARNING NR 26//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 25W (LAN), LOCATED APPROXIMATELY 303 NM EAST
OF KADENA AB, HAS TRACKED NORTH-NORTHEASTWARD AT 18 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS
A SYMMETRIC EYEWALL SURROUNDING A 38NM ROUND EYE. UPPER-LEVEL
ANALYSIS INDICATES EXCELLENT OUTFLOW, PARTICULARLY POLEWARD, WHICH
IS TAPPING INTO THE MIDLATITUDE WESTERLIES OVER JAPAN. A 211825Z
NOAA-19 89GHZ IMAGE SHOWS AN EXTENSIVE BAND OF DEEP CONVECTION OVER
THE WESTERN SEMI-CIRCLE ASSOCIATED WITH A COLD SURGE AND STRONG
CONVERGENT FLOW. AS A RESULT, THE 34-KNOT WIND RADII ARE EXTENSIVE
AS EVIDENCED BY SURFACE WIND OBSERVATIONS OVER THE RYUKYU ISLANDS
RANGING FROM 30 TO 45 KNOTS. THE INITIAL INTENSITY IS ASSESSED AT
135 KNOTS BASED ON DVORAK INTENSITY ESTIMATES RANGING FROM T6.5 (127
KNOTS) TO T7.0 (140 KNOTS). THE STY ESTIMATE WAS VALIDATED YESTERDAY
BY AIRCRAFT RECONNAISSANCE DATA FROM JAPAN WITH MAXIMUM WINDS AND
MINIMUM SLP IN THE EYEWALL SUPPORTING AN INTENSITY OF 125 TO 130
KNOTS. STY 25W IS ACCELERATING POLEWARD ALONG THE WESTERN PERIPHERY
OF THE DEEP LAYERED SUBTROPICAL RIDGE.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. THIS FORECAST REMAINS HIGHLY
CONSISTENT WITH THE PREVIOUS JTWC FORECASTS. WIND RADII HAVE BEEN
ADJUSTED PRECISELY BASED ON A DETAILED ANALYSIS OF THE 211237Z ASCAT
IMAGE (SUPPORTS UNUSUALLY SMALL 50- AND 64-KNOT WIND RADII) AS WELL
AS RYUKYU ISLAND SURFACE OBSERVATIONS.
   B.  ANIMATED SATELLITE IMAGERY INDICATES SOME EYE WOBBLE,
HOWEVER, STY 25W IS TRACKING GENERALLY POLEWARD TOWARD CENTRAL
JAPAN. DYNAMIC MODEL GUIDANCE REMAINS IN STABLE AND REMARKABLY TIGHT
AGREEMENT WITH ONLY A 60-NM SPREAD IN SOLUTIONS OVER THE KANTO PLAIN
REGION NEAR TAU 24. STY LAN SHOULD WEAKEN SLIGHTLY THROUGH TAU 12
WITH SIGNIFICANT WEAKENING AFTER TAU 12 ASSOCIATED WITH INCREASED
INTERACTION WITH LAND AND THE STRONG BAROCLINIC ZONE AS WELL
INCREASING VERTICAL WIND SHEAR. THE SYSTEM WILL COMPLETE EXTRA-
TROPICAL TRANSITION NEAR TAU 24 AS IT GAINS FRONTAL CHARACTERISTICS
AND BEGINS TO ACCELERATE NORTHEASTWARD. STY 25W IS FORECAST TO
MAINTAIN EXTENSIVE GALE-FORCE WINDS DUE TO THE VERY LARGE SIZE OF
THE SYSTEM, AND PROXIMITY OF COLD-SURGE WINDS AND GRADIENT WINDS
ASSOCIATED WITH THE FRONTAL ZONE CURRENTLY SITUATED OVER JAPAN.
DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGHOUT THE
FORECAST PERIOD, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST TRACK.//
NNNN
NNNN