Tropical Storm KROSA Advisory 10 Αυγ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (KROSA) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 11W (KROSA), LOCATED APPROXIMATELY 150 NM SOUTH OF
IWO TO, JAPAN, HAS TRACKED NORTHWARD AT 01 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS DECAYING
DEEP CONVECTION OVER THE CORE AND NORTHWEST QUADRANT DUE TO THE
PRESENCE OF CYCLONIC FLOW AND CONVERGENCE ALOFT. HOWEVER, STRONG
DIFFLUENCE OVER THE EASTERN AND SOUTHERN FLANK CONTINUE TO FUEL DEEP
CONVECTIVE BANDING, WHICH IS WRAPPING TIGHTLY INTO THE LOW-LEVEL
CIRCULATION CENTER (LLCC). A 092017Z SSMIS 37GHZ IMAGE INDICATES
TIGHTLY-CURVED BANDING WRAPPING INTO A DEFINED LLCC, WHICH SUPPORTS
THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS
ASSESSED AT 75 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF
4.5 (77 KNOTS) FROM RJTD AND PGTW. WITH THE EXCEPTION OF THE
COMPLEX, MARGINALLY-FAVORABLE OUTFLOW, VERTICAL WIND SHEAR AND SST
VALUES REMAIN FAVORABLE. TY 11W IS LOCATED WITHIN A WEAK STEERING
ENVIRONMENT WITH A NORTH-SOUTH SUBTROPICAL RIDGE POSITIONED TO THE
EAST, A WEAK STR OVER WESTERN JAPAN AND A BREAK TO THE NORTH.
THEREFORE, TY 11W IS TRACKING SLOWLY POLEWARD (AND ERRATICALLY).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. IN THE NEXT 72 HOURS, THE PRIMARY STEERING FOR TY 11W WILL
GRADUALLY TRANSITION TO THE BUILDING STR TO THE NORTH OF TY 11W AND
THE TRACK WILL SLOWLY SHIFT NORTHWESTWARD TOWARD JAPAN, PASSING
SOUTHWEST OF IWO TO AROUND TAU 36. SLIGHTLY DIMINISHED OUTFLOW, WEAK
SUBSIDENCE AND POSSIBLE UPWELLING COOLER WATER WILL MAKE THE
ENVIRONMENT SOMEWHAT UNFAVORABLE THROUGH TAU 48 WITH GRADUAL
WEAKENING TO ABOUT 60 KNOTS. AFTER TAU 48, AS THE SYSTEM BEGINS TO
ACCELERATE WEST-NORTHWESTWARD TO NORTHWESTWARD OVER WARM SST, SLIGHT
INTENSIFICATION IS EXPECTED.
   C. AFTER TAU 72, TY 11W WILL RECURVE POLEWARD ALONG THE SOUTHWEST
PERIPHERY OF THE STR, WHICH IS EXPECTED TO WEAKEN AND REORIENT WITH
THE APPROACH OF A DEEP MIDLATITUDE SHORTWAVE TROUGH. TY 11W SHOULD
RE-INTENSIFY TO A PEAK INTENSITY OF 70 KNOTS AS POLEWARD OUTFLOW
IMPROVES. SST VALUES WILL REMAIN CONDUCIVE (28-29C) DURING THIS
EXTENDED PERIOD. NUMERICAL MODEL GUIDANCE DIVERGES SLIGHTLY BUT
REMAINS IN GOOD AGREEMENT WITH A 125NM SPREAD IN SOLUTIONS AT TAU
120. BASED ON THE ERRATIC SHORT-TERM MOTION AND UNCERTAINTY IN THE
LATER TAUS, THERE IS OVERALL MODERATE CONFIDENCE IN THE JTWC
FORECAST TRACK.//
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