Tropical Storm MALAKAS Advisory Fri Sep 16

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (MALAKAS) WARNING NR 20//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
  TYPHOON 18W (MALAKAS), LOCATED APPROXIMATELY 361 NM SOUTHWEST OF
KADENA AB, HAS TRACKED NORTH-NORTHWESTWARD AT 11 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A
161017Z SSMIS 91 GHZ IMAGE DEPICTS IMPROVED DEEP CONVECTION AND A
WELL DEFINED 10 NM EYE FEATURE. THE INITIAL POSITION IS BASED ON
SATELLITE EYE FIXES FROM PGTW AND RJTD WITH GOOD CONFIDENCE. THE
INITIAL INTENSITY IS ASSESSED AT 110 KNOTS AND IS BASED ON AN
AVERAGE OF DVORAK ESTIMATES FROM ALL AGENCIES RANGING FROM T5.5 TO
T6.0 (102 TO 115 KNOTS). UPPER-LEVEL ANALYSIS SHOWS CONSIDERABLE
IMPROVEMENT IN BOTH EQUATORWARD AND POLEWARD OUTFLOW CHANNELS
LEADING TO THE RECENT INCREASE IN INTENSITY. SEA SURFACE
TEMPERATURES ARE CURRENTLY VERY FAVORABLE NEAR 29 TO 30 CELSIUS.
CURRENTLY TY MALAKAS IS TRACKING NORTHWESTWARD ALONG THE PERIPHERY
OF A DEEP-LAYERED SUBTROPICAL RIDGE TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. IN THE NEAR TERM FORECAST TY MALAKAS WILL CONTINUE TO TRACK
NORTHWESTWARD OVER THE NEXT 24 HOURS UNDER THE INFLUENCE OF THE
STEERING RIDGE. BEYOND TAU 24 THE SUBTROPICAL RIDGE WILL REORIENT AS
A SHORTWAVE TROUGH MOVES IN FROM THE WEST, AND THE TRACK WILL SHIFT
TO THE NORTHEAST AS TY MALAKAS ROUNDS THE RIDGE AXIS. SLIGHT
INTENSIFICATION IS EXPECTED OVER THE NEXT 12 HOURS AS CONDITIONS
REMAIN FAVORABLE, BUT A WEAKENING TREND WILL BEGIN SHORTLY AFTERWARD
AS LAND INTERACTION WITH NORTHERN TAIWAN TAKES PLACE. THE WEAKENING
TREND WILL CONTINUE AS TY MALAKAS TURNS NORTHEASTWARD UNDER THE
INFLUENCE OF STRONG WESTERLY FLOW AND INCREASED VERTICAL WIND
SHEAR.
   C. IN THE EXTENDED TAUS, TY MALAKAS WILL CONTINUE NORTHEAST,
GRADUALLY WEAKENING UNDER THE WESTERLY JET AND MAKE LANDFALL ON
KYUSHU NEAR TAU 90. SOMETIME BETWEEN TAU 96 AND 120 TY MALAKAS WILL
BEGIN TO TRANSITION INTO AN EXTRATROPICAL SYSTEM. DYNAMIC MODEL
GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 36 GIVING HIGH CONFIDENCE
TO THIS PORTION OF THE FORECAST TRACK. HOWEVER, THERE IS
DISAGREEMENT IN THE NUMERICAL SOLUTIONS IN THE SPEED AT WHICH TY
MALAKAS WILL ADVANCE ALONG ITS NORTHEASTWARD TRACK, LENDING LOW
CONFIDENCE TO THIS PORTION OF THE FORECAST TRACK.//
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