#76 Postby euro6208 » Sun Aug 23, 2020 10:49 pm
WDPN31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 09W (BAVI), LOCATED APPROXIMATELY 108 NM WEST-NORTHWEST
OF KADENA AB, HAS TRACKED NORTHEASTWARD AT 05 KNOTS OVER THE PAST SIX
HOURS. THE CURRENT POSITION IS BASED ON A RECENT PGTW SATELLITE FIX,
RADAR IMAGERY FROM OKINAWA AND A LOW-LEVEL EYE FEATURE EVIDENT IN
232245Z SSMIS 37 GHZ MICROWAVE SATELLITE IMAGERY. THE INTENSITY IS
SET A BIT BELOW SUBJECTIVE DVORAK ESTIMATES OF 77 KNOTS FROM PGTW AND
KNES TO ACCOUNT FOR LOWER AUTOMATED INTENSITY ESTIMATES RANGING FROM
55 TO 60 KNOTS AND A SUBJECTIVE DVORAK ESTIMATE OF 55 KNOTS FROM
RJTD. THE STRONG CONVECTIVE SIGNATURE AND EYE DEVELOPMENT EVIDENT IN
MICROWAVE SATELLITE IMAGERY SUPPORT AN INTENSITY CLOSER TO THE HIGHER
END SUBJECTIVE DVORAK VALUES. TY 09W HAS CONTINUED TO INTENSIFY OVER
THE PAST SIX HOURS UNDER THE ONGOING INFLUENCE OF LOW (10-15 KNOTS)
VERTICAL WIND SHEAR (VWS), VERY WARM (29-30C) SEA SURFACE
TEMPERATURES (SSTS) AND FAVORABLE RADIAL DIFFLUENCE ALOFT. THE SYSTEM
IS TURNING SLOWLY POLEWARD AS THE PRIMARY STEERING MECHANISM BEGINS
TO SHIFT FROM A STEERING RIDGE TO THE SOUTHEAST TO BUILDING
SUBTROPICAL RIDGING TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 09W WILL CONTINUE TO TURN POLEWARD OVER THE NEXT 12 HOURS AS
THE BUILDING SUBTROPICAL RIDGE TO THE EAST BECOMES THE DOMINANT
STEERING MECHANISM. STEADY TO RAPID INTENSIFICATION IS ANTICIPATED
DUE TO FAVORABLE VWS, SSTS AND UPPER-LEVEL OUTFLOW. RECENT ANIMATED
WATER VAPOR SATELLITE IMAGERY AND CONCURRENT ATMOSPHERIC MOTION
VECTORS INDICATE A DEVELOPING OUTFLOW CHANNEL ENHANCED BY AN UPPER
TROPOSPHERIC TROUGH TO THE WEST. THE NOTED COMBINATION OF FAVORABLE
ENVIRONMENTAL FACTORS MAKE RAPID INTENSIFICATION ABOVE THE INTENSITY
VALUES REFLECTED IN THE CURRENT FORECAST A DISTINCT POSSIBILITY. BY
TAU 72, TY 09W WILL BEGIN THE FIRST PHASE OF EXTRATROPICAL TRANSITION
AS IT INTERACTS WITH A DEVELOPING MID-LATITUDE TROUGH. SIMULTANEOUS
WEAKENING IS ANTICIPATED PRIMARILY DUE TO INCREASING VWS ASSOCIATED
WITH THE MID-LATITUDE TROUGH INTERACTION. NUMERICAL MODEL GUIDANCE IS
IN GOOD AGREEMENT WITH RESPECT TO THE OVERALL TRACK FORECAST
SCENARIO. HOWEVER, THERE IS NOTEWORTHY SPREAD BETWEEN THE WESTERNMOST
CONSENSUS MEMBERS, INCLUDING THE ECMWF MODEL, AND THE EASTERNMOST
MEMBERS, INCLUDING THE GFS MODEL. NONE OF THE AVAILABLE MODEL
FORECASTS INDICATE CENTER PASSAGE OVER SOUTH KOREA, BUT THE EASTERN
GROUP DOES CARRY THE CENTER ALONG THE WESTERN SHORE. THE MULTI-MODEL
CONSENSUS HAS BEEN VERY CONSISTENT FOR MULTIPLE MODEL RUNS. THUS THE
CURRENT JTWC TRACK FORECAST IS SITUATED NEAR THE CONSENSUS, AND
PREVIOUS JTWC FORECASTS, WITH FAIR AND INCREASING CONFIDENCE.
C. TY 09W IS EXPECTED TO MAKE LANDFALL SOMEWHERE NEAR THE BORDER
BETWEEN NORTH KOREA AND NORTHEASTERN CHINA ALONG THE YELLOW SEA
COAST. THE SYSTEM WILL ACCELERATE POLEWARD OVER LAND AS IT BECOMES
FULLY EMBEDDED IN THE AFOREMENTIONED MID-LATITUDE TROUGH. RAPID
WEAKENING IS ANTICIPATED DUE TO UNFAVORABLE UPPER-LEVEL CONDITIONS
AND PASSAGE OVER LAND. THE SYSTEM WILL BE FULLY EXTRATROPICAL BY TAU
96.
NNNN
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