Original source: http://tgftp.nws.noaa.gov/data/raw/wd/wdpn31.pgtw..txt, recovered at: 2017-09-13 2045Z

WDPN31 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (TALIM) WARNING NR 21//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 20W (TALIM), LOCATED APPROXIMATELY 159 NM WEST OF KADENA
AB HAS TRACKED NORTHWESTWARD AT 6 KNOTS OVER THE PAST SIX HOURS.
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES DEEP
CONVECTION CONTINUING TO WRAP INTO A RAGGED 38-NM EYE FEATURE. A
131536Z GPM 37 GHZ MICROWAVE IMAGE SHOWED AN EYEWALL OF VERY
INTENSE CONVECTION NEARLY SURROUNDING THE ENTIRE EYE, THOUGH WITH A
SMALL BREAK INTO THE EAST SIDE. BASED ON SUBSEQUENT ANIMATED
INFRARED IMAGERY, THE SYSTEM MAY BE UNDERGOING AN EYEWALL
REPLACEMENT CYCLE (ERC), WITH DEEP CONVECTION NOW FORMING AGAIN ON
THE EASTERN SIDE OF THE EYE. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON DVORAK FIX LOCATIONS FROM ALL AGENCIES AS
WELL AS RADAR FIX DATA FROM JMA. THE INITIAL INTENSITY IS SET AT
KNOTS AND IS BASED ON SUBJECTIVE DVORAK CURRENT INTENSITY
ESTIMATES OF T5.5 (102 TO 125 KNOTS) FROM ALL REPORTING AGENCIES.
TY 20W IS LOCATED IN A NEARLY OPTIMUM ENVIRONMENT, WITH VERY HIGH
SEAS SURFACE TEMPERATURES AT OR ABOVE 31 DEG CELSIUS, STRONG DUAL
CHANNEL OUTFLOW COMBINED WITH A POINT SOURCE OVER THE SYSTEM, AND
LOW (5-10 KNOTS) VERTICAL WIND SHEAR (VWS), LEADING TO THE RAPID
INTENSIFICATION WITNESSED OVER THE PAST 18-24 HOURS. TY TALIM IS
DRIFTING SLOWLY NORTHWESTWARD IN A WEAK STEERING ENVIRONMENT IN A
COL AREA BETWEEN TWO SUBTROPICAL RIDGE (STR) CENTERS, ONE OVER
CHINA AND THE OTHER IN THE WESTERN PACIFIC AND AN EXTENSION OF THE
EASTERN STR LYING TO THE NORTH OF THE SYSTEM.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. OVER THE NEXT 24 HOURS, TY 20W WILL CONTINUE TO TRACK
GENERALLY NORTHWARD IN THE PREVIOUSLY MENTIONED WEAK STEERING
ENVIRONMENT. WITH THE RIDGE EXTENSION TO THE NORTH, NORTHWARD
MOTION WILL BE SLOW THROUGH THE FIRST 24 HOURS OF THE FORECAST. BY
TAU 36, THE NORTHERN RIDGE EXTENSION WILL WEAKEN AND MOVE
EASTWARDS, ALLOWING TY 20W TO BEGIN TO ROUND THE STR AXIS AND
ACCELERATE NORTHEASTWARDS. TY 20W IS EXPECTED TO MOVE NORTHEASTWARD
AT ABOUT 10 KNOTS, MAKING LANDFALL ALONG THE SOUTHERN PORTION OF
KYUSHU AROUND TAU 72. THE LOW SHEAR, HIGH SSTS, AND DUAL CHANNEL
OUTFLOW ENVIRONMENT WILL ALLOW THE SYSTEM TO CONTINUE TO INTENSIFY,
PEAKING AT 125 KNOTS BY TAU 36. AFTER TAU 36, THE SYSTEM WILL BEGIN
TO WEAKEN AS IT BEGINS TO ENCOUNTER INCREASING VWS AND THE
EQUATORWARD OUTFLOW CHANNEL IS CHOKED OFF BY A RIDGE WHICH DEVELOPS
TO THE SOUTH. DYNAMIC MODEL GUIDANCE IS IN VERY TIGHT AGREEMENT IN
THE TRACK THROUGH TAU 72, WITH NAVGEM BEING THE SOLE OUTLIER TO THE
SOUTH, INDICATING A SHARPER RECURVE AND KEEPING THE SYSTEM OFFSHORE
OF KYUSHU.
   C. IN THE EXTENDED FORECAST, TY TALIM WILL CONTINUE TO
ACCELERATE NORTHEASTWARD AS IT BECOMES EMBEDDED IN A MID-LATITUDE
TROUGH APPROACHING FROM THE WEST. AS THE SYSTEM ADVECTS LARGE
AMOUNTS OF WARM AIR AT THE SURFACE, THE DOWNSTREAM RIDGE WILL
BUILD, KEEPING TY 20W ON A TRACK WHICH WILL CROSS HONSHU AND INTO
THE SEA OF JAPAN BY TAU 96, THEREAFTER CONTINUING OVER HOKKAIDO AN
INTO THE SEA OF OKHOTSK BY TAU 120. THE SYSTEM WILL START TO BECOME
EXTRA-TROPICAL BY TAU 96 AND COMPLETE EXTRA-TROPICAL TRANSITION BY
TAU 120. TY 20W WILL CONTINUE TO WEAKEN AS IT CROSSES HONSHU AND
THEN HOKKAIDO DUE TO TERRAIN INTERACTION COMBINED WITH HIGH VWS AND
DECREASING SSTS. MODEL GUIDANCE IS IN VERY GOOD AGREEMENT ON THE
TRACK ACROSS JAPAN, BUT SHOWS SOME SIGNIFICANT SPEED DIFFERENCES
ALONG THE TRACK DUE TO THE UNCERTAINTY ASSOCIATED WITH THE MID-
LATITUDE TROUGH. WITH THE STRONG AGREEMENT IN THE OVERALL TRACK
THROUGH THE ENTIRE FORECAST, NOTWITHSTANDING THE SPEED DIFFERENCES,
THERE IS OVERALL HIGH CONFIDENCE IN THE JTWC FORECAST./=