Tropical Storm KROSA Advisory 15 Αυγ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR
037//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 11W (KROSA), LOCATED APPROXIMATELY 183 NM
SOUTH OF IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 09 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY
DEPICTS AN EXTENSIVE SYSTEM WITH A RAGGED LOW LEVEL CENTER SURROUNDED
BY POCKETS OF DEEP CONVECTION DISPLACED 50 TO 100 NM AWAY. THE
INITIAL POSITION IS BASED ON MULTI-AGENCY FIXES (INCLUDING RADAR)
WITH GOOD CONFIDENCE, AND SUPPORTED BY A 141715Z NPP PASS. THE
INITIAL INTENSITY IS ASSESSED AT 55 KNOTS AFTER RECENT 08-12Z
SCATTEROMETRY AND SMAP DATA INDICATED 50-PLUS KNOT WINDS WERE PRESENT
IN THE NORTHEAST QUADRANT AT THAT TIME. THESE PEAK WINDS WERE
DISPLACED 100 NM FROM THE CENTER, BUT CLEARLY ASSOCIATED WITH THE
BROAD CONVECTIVE FLOW. THEREFORE, THE 18Z INTENSITY ESTIMATE IS
MAINTAINING THE REVISED 12Z WIND ESTIMATE AND NOT INDICATIVE OF
ACTUAL INTENSIFICATION. DVORAK CURRENT INTENSITY ESTIMATES RANGE FROM
T3.0-T3.5 (45 TO 55 KNOTS) AND SATCON IS CURRENTLY AT 55 KNOTS. AN
EXTENSIVE AREA OF GALES SURROUNDS THE SYSTEM, HOWEVER, AGAIN THE PEAK
WINDS ARE ISOLATED AND DISPLACED WELL TO THE NORTHEAST OF THE CENTER.
 UPPER LEVEL OUTFLOW HAS CONTINUED TO IMPROVE AHEAD OF AN APPROACHING
MIDLATITUDE TROUGH TO ITS WEST, AND THE EQUATORWARD OUTFLOW CHANNEL
REMAINS EXCELLENT. SEA SURFACE TEMPERATURES (SST) REMAIN CONDUCIVE
(28-29 DEGREES CELSIUS). THE CYCLONE IS TRACKING NORTHWARD ALONG THE
WESTERN PERIPHERY OF AN EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. OVER THE NEXT 12 HOURS, TS 11W WILL CONTINUE ON ITS CURRENT
TRACK AS IT ROUNDS THE WESTERN PERIPHERY OF THE AFOREMENTIONED STR.
FORECAST PEAK WINDS AT LANDFALL WERE INCREASED DUE TO THE ADJUSTMENT
TO THE INITIAL INTENSITY, HOWEVER, PEAK WINDS ARE EXPECTED TO REMAIN
ISOLATED WELL AWAY FROM THE CENTER, AND OVER-LAND INTENSITIES SHOULD
BE WEAKER DUE TO TERRAIN AND FRICTIONAL EFFECTS. BEYOND TAU 12, A
MIDLATITUDE TROUGH WILL APPROACH FROM THE WEST, ERODING THE STR AND
ALLOWING TS 11W TO RECURVE POLEWARD AROUND THE STR AXIS. AFTER
RE-EMERGING INTO THE SEA OF JAPAN, GRADUAL WEAKENING IS FORECAST AS
SST DECLINES TO THE NORTH, AND VERTICAL WIND SHEAR INCREASES DUE TO
THE APPROACHING TROUGH. EXTRA-TROPICAL TRANSITION IS EXPECTED TO
BEGIN BY TAU 36, AND GUIDANCE INDICATES THIS TRANSITION WILL BE
COMPLETE BY TAU 48 AS KROSA WILL BE UNDERNEATH THE 200 MB
MID-LATITUDE BAROCLINIC FLOW. DYNAMICAL MODELS ARE IN EXCELLENT
AGREEMENT ON TRACK THROUGH TAU 48. THE JTWC FORECAST TRACK IS PLACED
CLOSE TO THE MULTI-MODEL CONSENSUS AND PRIOR FORECAST WITH HIGH
CONFIDENCE. //
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