Typhoon NOCK-TEN Update

[Jeb]

WDPN32 PGTW 250300

MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//

SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W

/WARNING NR 45//

RMKS/

1. FOR METEOROLOGISTS.

2. PROGNOSTIC REASONING FOR 250000Z7 TO 290000Z1 OCT 2004.

A. TYPHOON (TY) 28W (NOCK-TEN), LOCATED APPROXIMATELY 315

NM WEST-SOUTHWEST OF OKINAWA, JAPAN, HAS TRACKED NORTHWARD

AT 15 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS

BASED ON 242330Z4 MULTISPECTRAL SATELLITE IMAGERY. THE WARNING

INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES

OF 102 AND 115 KNOTS, AND ADJUSTED DOWNWARD FOR DECREASING

FINAL-T NUMBERS. RECENT ANIMATED SATELLITE IMAGERY SHOWS A

DECREASE IN DEEP CONVECTION DUE TO DRY AIR INTRUSION AND

INTERACTION WITH LAND.

B. TY 28W IS FORECAST TO TRACK NORTHWARD FOR THE NEXT 12

HOURS AS IT CRESTS THE SUBTROPICAL RIDGE AXIS, AND THEN

SHARPLY RECURVE ALONG THE NORTHWESTERN PERIPHERY OF THE

STEERING RIDGE. TY 28W WILL BEGIN TO TRANSITION INTO AN EXTRA-

TROPICAL CYCLONE AS IT INTERACTS WITH THE MID-LATITUDE BARO-

CLINIC ZONE BETWEEN TAU 24 AND TAU 36. THE AVAILABLE DYNAMIC

AIDS CONSISTING OF NOGAPS, COAMPS, GFDN, NCEP GFS, JGSM, JTYM,

UKMET, AFWA MM5, TCLAPS AND WBAR ARE IN GOOD AGREEMENT WITH

THIS SCENARIO THROUGH TAU 24. MODEL FORECASTS OF THE BAROCLINIC

INTERACTION VARY, WITH TWO DIFFERENT SCENARIOS EMERGING. UKMET,

NCEP GFS, AFWA MM5, WBAR, TCLAPS AND NOGAPS FORECAST A WEAK

INTERACTION CONSISTENT WITH THE CURRENT WEAK SYNOPTIC ENVIRON-

MENT, AND EMBED TY 28W INTO THE BAROCLINIC ZONE BY TAU 48. GFDN

AND COAMPS FORECAST A COMPLETE DECOUPLING OF THE SYSTEM, WITH

THE MID AND UPPER LEVELS BECOMING EMBEDDED IN THE MID-LATITUDE

FLOW, AND THE LOW LEVEL CIRCULATION TRACKING AROUND THE EASTERN

PERIPHERY OF AN ANTICYCLONE THAT DEVELOPS OVER CHINA WITHIN THE

NEXT 24 HOURS. GFDN FORECASTS A SIGNIFICANT DECREASE IN FORWARD

SPEED EARLY IN THE FORECAST AS THE SYSTEM IS SHEARED APART. THIS

FORECAST IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS

WITH LESS EMPHASIS PLACED ON GFDN AND COAMPS AFTER TAU 24.

C. THE INTENSITY OF TY 28W IS FORECAST TO DECREASE THROUGH

TAU 72 AS THE SYSTEM ENCOUNTERS DRY AIR AND COOLER SEA SURFACE

TEMPERATURES, AND INTERACTS WITH THE TERRAIN OF TAIWAN AND THE

MID-LATITUDE BAROCLINIC ZONE.

D. CURRENT WIND RADII ARE BASED ON A 242106Z7 QUIKSCAT PASS.

FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED

SYSTEM.

E. IN THE EXTENDED TAUS, TY 28W WILL BECOME EMBEDDED IN THE

BAROCLINIC ZONE AND COMPLETE EXTRATROPICAL TRANSITION SOUTH OF

JAPAN BY TAU 72. THE INTENSITY OF TY 28W IS FORECAST TO RAPIDLY

DECREASE AFTER TAU 72 AS THE SYSTEM ENCOUNTERS HIGHER VERTICAL

WIND SHEAR ASSOCIATED WITH THE MID-LATITUDE WESTERLIES AND COOLER

SEA SURFACE TEMPERATURES.

FORECAST TEAM: BOWER/MENEBROKER/FUNK//

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