Tropical Storm MALAKAS Advisory ven, 16.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (MALAKAS) WARNING NR 19//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
  TYPHOON 18W (MALAKAS), LOCATED APPROXIMATELY 274 NM SOUTH-
SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTHWESTWARD AT 13
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A TIGHTLY WOUND SPIRAL SYSTEM WITH A NEWLY FORMED
PINHOLE EYE IN THE LAST SIX HOURS WHICH IS ALREADY BEGINNING TO
FILL.  THE INITIAL POSITION IS BASED ON SATELLITE EYE FIXES FROM
PGTW AND RJTD WITH GOOD CONFIDENCE.  THE INITIAL INTENSITY IS
ASSESSED AT 90 KNOTS AND IS BASED ON RECENT DVORAK ESTIMATES FROM
PGTW AND RJTD REPORTING THE CURRENT INTENSITY AS T5.0 (90 KNOTS).
THE INITIAL WIND DISTRIBUTION WAS ADJUSTED SLIGHTLY TO REFLECT DATA
OBTAINED FROM A 160155Z METOP-B ASCAT IMAGE SHOWING THE EXTENT OF
THE 35 AND 50 KNOT WIND RADII TO BE LESS THAN PREVIOUSLY THOUGHT.
UPPER-LEVEL ANALYSIS SHOWS MODERATE RADIAL OUTFLOW AND LOW VERTICAL
WIND SHEAR WITH A TUTT CELL TO THE EAST. 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, ENHANCING OUTFLOW. THE
TRACK WILL SHIFT TO THE NORTHEAST AS TY MALAKAS ROUNDS THE RIDGE
AXIS. SLIGHT INTENSIFICATION IS EXPECTED AS CONDITIONS IMPROVE, BUT
WILL BEGIN A WEAKENING TREND AS THE WIND FIELD IS DISRUPTED FROM
LAND INTERACTION WITH NORTHERN TAIWAN. THE WEAKENING TREND WILL
CONTINUE AS STRONG WESTERLY FLOW INCREASES VERTICAL WIND SHEAR.
   C. IN THE EXTENDED TAUS, TY MALAKAS WILL CONTINUE NORTHEAST,
GRADUALLY WEAKENING UNDER THE WESTERLY JET. 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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