Tropical Storm MALAKAS Advisory Tue Sep 20

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (MALAKAS) WARNING NR 31//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
    TYPHOON (TY) 18W (MALAKAS), LOCATED APPROXIMATELY 188 NM
SOUTH-SOUTHWEST OF SASEBO, JAPAN, HAS TRACKED NORTHEASTWARD AT 13
KNOTS OVER THE PAST SIX HOURS.  ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) SHOWS THE SYSTEM HAS MAINTAINED ITS CONVECTIVE SIGNATURE AND A
WELL-DEFINED 10-NM EYE. THE INITIAL POSITION IS BASED ON THE EYE
FEATURE WHICH LINES UP WITH A SYMMETRIC MICROWAVE EYE FEATURE IN
THE 190311Z GCOM PASS. THE INITIAL INTENSITY OF 105 KNOTS IS BASED ON
CONGRUENT DVORAK ESTIMATES FROM PGTW AND RJTD. UPPER-LEVEL ANALYSIS
INDICATES THE SYSTEM IS IN MODERATE TO STRONG (20-25 KNOT) SOUTHERLY
VERTICAL WIND SHEAR (VWS); HOWEVER, THE VWS IS OFFSET BY THE IN-PHASE
STORM MOTION, EXCELLENT DUAL OUTFLOW AND WARM SEA SURFACE
TEMPERATURES. THE CYCLONE IS TRACKING ALONG THE NORTHWESTERN
PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 18W WILL ACCELERATE NORTHEASTWARD ON THE POLEWARD SIDE OF
THE STR AS IT BECOMES EMBEDDED DEEPER INTO THE STRONG MID-LATITUDE
WESTERLIES. IT IS EXPECTED TO MAKE LANDFALL IN KYUSHU BEFORE TAU 12.
TY MALAKAS WILL THEN DRAG ACROSS THE SOUTHERN COAST OF JAPAN. THE
LAND INTERACTION, IN ADDITION TO STRONG VWS (GREATER THAN 40 KNOTS),
WILL CAUSE ITS RAPID DISSIPATION. CONCURRENTLY, THE CYCLONE WILL
UNDERGO EXTRA-TROPICAL TRANSITION. THE NUMERIC GUIDANCE REMAINS IN
TIGHT AGREEMENT WITH SOME DIFFERENCES IN LATERAL SPEED, BUT OVERALL,
THE TIGHT GROUPING LENDS FAIR CONFIDENCE IN THE JTWC TRACK FORECAST.//
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