Tropical Storm KROSA Advisory Sun Aug 11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (KROSA) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 11W (KROSA), LOCATED APPROXIMATELY 115 NM SOUTH OF
IWO TO, HAS TRACKED WEST-NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX
HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS
CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION
CENTER (LLCC). HOWEVER, DEEP CONVECTION OVER THE CORE AND NORTHWEST
QUADRANT REMAINS COMPARATIVELY WEAK DUE TO THE PRESENCE OF CYCLONIC
FLOW AND CONVERGENCE ALOFT WHILE STRONG DIFFLUENCE OVER THE EASTERN
AND SOUTHERN FLANK CONTINUE TO FUEL DEEP CONVECTIVE BANDING. A 100520
SSMI 85GHZ IMAGE INDICATES TIGHTLY-CURVED BANDING WRAPPING INTO A
DEFINED, BROAD LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 65 KNOTS, HEDGED
SLIGHTLY BELOW DVORAK CURRENT INTENSITY ESTIMATES OF 4.5 (77 KNOTS)
BASED ON WARMING CLOUD TOPS ACROSS THE SOUTHERN PERIPHERY. 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 WITH
A NORTHWESTWARD TRACK TOWARD JAPAN, PASSING SOUTHWEST OF IWO TO
AROUND TAU 12. SLIGHTLY DIMINISHED OUTFLOW, WEAK SUBSIDENCE AND
POSSIBLE UPWELLING OF 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 BEGIN TO RECURVE POLEWARD ALONG THE
SOUTHWEST
PERIPHERY OF THE STR TO THE NORTH, 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 UNTIL UPPER LEVEL CONVERGENCE AND LAND INTERACTION
GRADUALLY WEAKENS TY 11W. SST VALUES WILL REMAIN CONDUCIVE (28-29C)
DURING THIS EXTENDED PERIOD. NUMERICAL MODEL GUIDANCE DIVERGES
SLIGHTLY BUT REMAINS IN GOOD AGREEMENT WITH SOME UNCERTAINTY IN TRACK
SPEED AS TY 11W APPROACHES THE SOUTHERN COAST OF KYUSHU. BASED ON THE
ERRATIC SHORT-TERM MOTION AND UNCERTAINTY IN THE LATER TAUS, THERE IS
OVERALL MODERATE CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN
NNNN