Tropical Storm TALIM Advisory Thu Sep 14

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (TALIM) WARNING NR 25//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 20W (TALIM), LOCATED APPROXIMATELY 195 NM WEST-NORTHWEST
OF KADENA AB, HAS TRACKED NORTHWARD AT 05 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A
WEAKENING SYSTEM, WITH LITTLE DEEP CONVECTION AT WARNING TIME.
THERE HAVE BEEN NO RECENT MICROWAVE PASSES OVER THE STORM, BUT A
141255Z AMSU-B 89 GHZ MICROWAVE IMAGE DEPICTED A VERY WIDE (60 NM)
BUT WELL-DEFINED EYE FEATURE, WITH WEAK CONVECTION WRAPPING INTO
THE CENTER. THE CURRENT POSITION IS PLACED WITH HIGH CONFIDENCE ON
RECENT SATELLITE EYE FIXES FROM PGTW AND RJTD. THE INITIAL
INTENSITY IS ASSESSED AT 95 KNOTS CONSISTENT WITH DVORAK CURRENT
INTENSITY ESTIMATES BETWEEN T4.5 (77 KNOTS) AND T5.5 (102 KNOTS)
FROM MULTIPLE REPORTING AGENCIES. TY 20W APPEARS TO HAVE STARTED TO
MOVE AT A SLIGHTLY QUICKER PACE OVER THE PAST SIX HOURS, NOW MOVING
TO THE NORTH AROUND 5 KNOTS, INDICATING THAT IT HAS OR IS IN THE
PROCESS OF ROUNDING THE SUBTROPICAL RIDGE (STR) AXIS. UPPER-LEVEL
ANALYSIS INDICATES THE SYSTEM RESIDES IN AN OVERALL FAVORABLE
ENVIRONMENT, WITH MODERATE VERTICAL WIND SHEAR (VWS), AND STRONG
POLEWARD OUTFLOW. HOWEVER, THESE FAVORABLE FACTORS ARE BEING OFFSET
BY THE UPWELLING OF SIGNIFICANTLY COOLER WATERS AND THE LOSS OF THE
EQUATORWARD OUTFLOW CHANNEL, RESULTING IN THE RAPID WEAKENING TREND
SEEN OVER THE PAST SIX HOURS.
   A. NEAR-TERM FORECAST INTENSITIES HAVE BEEN ADJUSTED DOWNWARD
BASED ON OBSERVED TRENDS IN THE CONVECTIVE SIGNATURE. OTHERWISE,
THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 20W IS EXPECTED TO SLOWLY ROUND THE STEERING RIDGE AXIS
OVER THE NEXT 12 HOURS THEN START TO ACCELERATE NORTHEASTWARD AHEAD
OF A DEVELOPING MID-LATITUDE TROUGH, REMAINING ON A GENERALLY
NORTHEASTWARD TRACK THROUGH TAU 72. THE SYSTEM IS EXPECTED TO
UNDERGO ADDITIONAL WEAKENING THROUGH TAU 24, AS IT CONTINUES TO
MOVE SLOWLY OVER WATERS WHICH HAVE COOLED DUE TO UPWELLING. A BRIEF
PERIOD OF EQUILIBRIUM AT 80 KNOTS IS EXPECTED BETWEEN TAUS 24 AND
36, AS THE SYSTEM MOVES OVER WARMER WATERS, WHILE TAPPING INTO THE
DIVERGENT FLOW AHEAD OF THE NEGATIVELY TILTED MID-LATITUDE TROUGH.
TY 20W IS FORECAST TO MAKE LANDFALL OVER SOUTHERN KYUSHU NEAR TAU
48 AND DECREASE IN INTENSITY AS IT TRANSITS ACROSS KYUSHU AND
HONSHU BEFORE REEMERGING IN THE SEA OF JAPAN. THE SYSTEM WILL BEGIN
EXTRATROPICAL TRANSITION PRIOR TO TAU 72 AS IT ENCOUNTERS
BAROCLINIC FLOW ASSOCIATED WITH THE TROUGH. NUMERICAL MODEL
GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THIS PORTION OF THE
FORECAST, LENDING HIGH CONFIDENCE TO THE JTWC OFFICIAL FORECAST
TRACK THROUGH TAU 72.
   C. DURING THE EXTENDED FORECAST PERIOD, TY 20W WILL RAPIDLY
TRANSIT NORTHEASTWARD AS IT BECOMES FULLY EMBEDDED IN THE
AFOREMENTIONED MID-LATITUDE TROUGH. EXTRATROPICAL TRANSITION IS
EXPECTED TO BE COMPLETE BY TAU 96. FAVORABLE BAROCLINIC SUPPORT
FROM THE MID-LATITUDE TROUGH WILL ALLOW THE SYSTEM TO BECOME AN
INTENSE EXTRATROPICAL LOW WITH EXTENSIVE GALE FORCE WINDS, AS
REFLECTED IN THE CURRENT FORECAST. NUMERICAL MODEL GUIDANCE REMAINS
IN GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD, LENDING
HIGH CONFIDENCE TO THE JTWC OFFICIAL FORECAST TRACK.//
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