Tropical Storm KROSA Advisory Sat Aug 10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (KROSA) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 11W (KROSA), LOCATED APPROXIMATELY 168 NM SOUTH OF
IWO TO, HAS TRACKED EASTWARD AT 01 KNOTS OVER THE PAST SIX HOURS.
THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION BASED ON A 30 NM
RAGGED EYE IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI).
ENHANCED INFRARED IMAGERY REVEALS AN AREA OF WARMER CLOUD TOP
TEMPERATURES OVER ABOUT 70 PERCENT OF THE EYEWALL. THE INITIAL
INTENSITY OF 85 KTS IS CONSISTENT WITH A T4.5-5.0 (77-90 KTS)
MULTI-AGENCY DVORAK FIX CURRENT INTENSITY ESTIMATE. THIS IS FURTHER
SUPPORTED BY A 090710Z ADT ESTIMATE OF 85 KTS. THE ENVIRONMENT IS
FAIRLY SUPPORTIVE WITH WEAKENING EQUATORWARD AND EASTWARD OUTFLOW,
LOW (05-10 KT) VERTICAL WIND SHEAR (VWS), AND WARM (29-30 CELSIUS)
SEA SURFACE TEMPERATURE BEING PARTIALLY OFFSET BY SUBSIDENCE ALONG
THE NORTHWESTERN SECTOR DUE TO AN INDUCED UPPER-LEVEL TROUGH. TY 11W
IS QUASI-STATIONARY IN A COMPLEX STEERING ENVIRONMENT WITH A NEAR
EQUATORIAL RIDGE (NER) TO THE SOUTH AND A SUBTROPICAL RIDGE (STR) TO
THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. IN THE NEXT 72 HOURS, PRIMARY STEERING FOR TY 11W WILL
GRADUALLY TRANSITION TO THE STR TO THE NORTH OF TY 11W AND THE TRACK
WILL SLOWLY SHIFT NORTHWESTWARD TOWARD JAPAN, PASSING IWO TO AROUND
TAU 36. SLIGHTLY DIMINISHED OUTFLOW, WEAK ENVIRONMENTAL SUBSIDENCE,
AND CONTINUED MARGINAL VWS WILL MAKE THE ENVIRONMENT SOMEWHAT
UNFAVORABLE AND WEAKENING TO 65 KTS IS ANTICIPATED BY TAU 72. MODEL
TRACK GUIDANCE GENERALLY AGREES WITH THE JTWC FORECAST TRACK FORECAST
FOR THIS PORTION OF THE FORECAST. HOWEVER, GIVEN HIGH UNCERTAINTY AS
TO WHEN TY 11W TRANSITIONS BETWEEN STEERING MECHANISMS, THERE IS LOW
CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.
   C. AFTER TAU 72, TY 11W WILL CONTINUE TRACKING NORTHWESTWARD UNDER
THE INFLUENCE OF THE STR UNTIL TAU 96 WHEN IT SHIFTS MORE NORTHWARD
AS IT BEGINS TO ROUND THE STR AXIS. INTENSITY IS EXPECTED TO
GRADUALLY WEAKEN AS THE UPPER LEVEL DIVERGENCE AND SHEAR BECOME
SLIGHTLY LESS FAVORABLE. IN THE EXTENDED PERIOD, NAVGEM BECOMES AN
OBVIOUS EASTERN OUTLIER AND THE JTWC TRACK FORECAST IS PLACED JUST
WEST OF THE CONSENSUS TRACK TO OFFSET THE OUTLIER. TRACK SPREAD AT
TAU 120 IS APPROXIMATELY 250NM. BASED ON HIGH UNCERTAINTY IN THE NEAR
TERM FORECAST, CONFIDENCE IN THE JTWC TRACK FORECAST REMAINS LOW IN
THE EXTENDED PERIOD.//
NNNN
NNNN