Tropical Storm HAISHEN Advisory Thu Sep 03

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HAISHEN) WARNING NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 11W (HAISHEN), LOCATED APPROXIMATELY 700 NM EAST-
SOUTHEAST OF KADENA AB, OKINAWA, HAS TRACKED WEST-NORTHWESTWARD AT
09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH AN INCIPIENT
RAGGED EYE FORMING OVER THE NORTHWEST EDGE OF THE CENTRAL
DENSE OVERCAST. A 030007Z AMSU 89GHZ MICROWAVE IMAGE DEPICTS A SMALL
MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD
CONFIDENCE. THE COMPACT CONVECTIVE CORE, PRESENCE OF A CYAN RING IN
RECENT MICROWAVE IMAGERY AND EMERGENCE OF A PINHOLE EYE IN VISIBLE
IMAGERY SUGGEST AN IMMINENT RAPID INTENSIFICATION PHASE. THE INITIAL
INTENSITY IS ASSESSED AT 85 KNOTS BASED ON DVORAK INTENSITY
ESTIMATES RANGING FROM T4.5 (77 KNOTS) TO T5.0 (90 KNOTS). UPPER-
LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH LOW VERTICAL
WIND SHEAR (VWS) AND NEAR-RADIAL OUTFLOW. ADDITIONALLY, SST VALUES
(30-31C) AND HIGH OCEAN HEAT CONTENT VALUES ARE CONDUCIVE FOR
FURTHER DEVELOPMENT. THE 02/1200Z 500MB ANALYSIS SHOWS A DEEP
MIDLATITUDE SHORTWAVE TROUGH OVER THE EAST CHINA SEA AND WESTERN
JAPAN WITH A BROAD SUBTROPICAL RIDGE ENTRENCHED NORTH OF THE SYSTEM.
A COL REGION IS POSITIONED NORTHWEST OF THE SYSTEM AND NORTHEAST OF
OKINAWA WITH MID-LEVEL WESTERLY FLOW OVER OKINAWA REFLECTING THE
POSITION OF THE AFOREMENTIONED TROUGH. TY 11W IS TRACKING WEST-
NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) AND IS TRACKING TOWARD THE COL REGION.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE LAST PROGNOSTIC REASONING MESSAGE.
   B. THE STR IS FORECAST TO BUILD AND REMAIN STATIONARY OVER JAPAN
WITH THE SHORTWAVE TROUGH GRADUALLY FILLING OVER THE KOREAN
PENINSULA. TY 11W WILL TRACK POLEWARD THROUGH THE BREAK (COL) IN THE
STR ALONG THE EASTERN EDGE OF THE SHORTWAVE TROUGH THROUGH TAU 72.
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A SPREAD OF 70NM
AT TAU 72...CURRENTLY ALL TRACKERS FORECAST THE SYSTEM TO PASS EAST
AND NORTHEAST OF OKINAWA. THE 02/12Z ECMWF ENSEMBLE ALSO SHOWS ALL
SOLUTIONS EAST OF OKINAWA. TY 11W IS FORECAST TO RAPIDLY INTENSIFY
OVER THE NEXT 24 TO 36 HOURS WITH A PEAK INTENSITY OF 130 KNOTS
EXPECTED AT TAU 36, HOWEVER, THE PEAK MAY OCCUR EARLIER IN THE
FORECAST PERIOD.
   C. IN THE EXTENDED PERIOD, NUMERICAL MODEL GUIDANCE DIVERGES WITH
INCREASING UNCERTAINTY IN THE EXACT TRACK, WHICH COULD SHIFT
EASTWARD CLOSER TO KYUSHU--THE BULK OF THE 02/12Z ECMWF SOLUTIONS
ARE CLUSTERED FROM 129-131E NEAR KYUSHU. TY 11W IS FORECAST TO BEGIN
EXTRA-TROPICAL TRANSITION (ETT) BY TAU 96 AS IT INTERACTS WITH THE
SHORTWAVE TROUGH AND WILL ACCELERATE POLEWARD AND COMPLETE ETT BY
TAU 120 WHEN IT GAINS FRONTAL CHARACTERISTICS OVER NORTH KOREA.
OVERALL, THERE IS MODERATE CONFIDENCE IN THE JTWC FORECAST TRACK,
WHICH IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.//
NNNN
NNNN