T.S. TALAS Prognosis for Dec 12

[Jeb]

WDPN31 PGTW 121500

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

SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 31W WARNING NR 11//

RMKS/

1. FOR METEOROLOGISTS.

2. PROGNOSTIC REASONING FOR 121200Z6 TO 171200Z1 DEC 2004.

A. TROPICAL STORM (TS) 31W (TALAS), LOCATED APPROXIMATELY 435 NM

EAST-SOUTHEAST OF GUAM, HAS TRACKED WESTWARD AT 20 KNOTS OVER THE

PAST 06 HOURS. THE WARNING POSITION IS BASED ON 121130Z8 ENHANCED

INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON

SATELLITE CURRENT INTENSITY ESTIMATES OF 45 AND 55 KNOTS.

B. TS 31W IS FORECAST TO RAPIDLY TRACK WESTWARD ALONG THE SOUTHERN

PERIPHERY OF THE SUBTROPICAL RIDGE ANCHORED TO THE NORTH FOR THE NEXT

12 TO 18 HOURS. THE SYSTEM WILL BEGIN TO SLOW ITS SPEED OF ADVANCE AS

IT BEGINS TO TRACK IN A MORE NORTHWESTWARD DIRECTION ALONG THE SOUTH-

WESTERN PERIPHERY OF THE MID LEVEL STEERING RIDGE AFTER TAU 72. THE

AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, EGRR, GFDN, JGSI, JTYI,

AVN, COAMPS, MM5, TCLAPS, AND WBAR ARE IN FARILY GOOD AGREEMENT.

TCLAPS AND COAMPS ARE THE POLEWARD OUTLIERS AND JGSI THE EQUATORWARD

OUTLIER. THIS FORECAST IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMIC

AIDS.

C. THE INTENSITY OF TS 31W IS EXPECTED TO INCREASE AT LESS THAN

A CLIMATOLOGICAL RATE DUE TO SURPRESSED OUTFLOW AND RAPID SPEED OF

ADVANCE.

D. CURRENT WIND RADII ARE BASED ON A 121031Z8 SSMI MICROWAVE PASS.

FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED

SYSTEM.

E. IN THE EXTENDED FORECAST TS 31W WILL BEGIN TO RECURVE POLEWARD

ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE AS A SHORT WAVE

TROUGH MOVES OVER THE EAST CHINA SEA CREATING A WEAKNESS IN THE RIDGE.

CONFIDENCE IN THE MODELS DURING THE LATE PERIOD OF THE FORECAST IS LOW

AS THERE IS A WIDE SPREAD IN THE MODELS.

3.FORECAST TEAM: PITTS/KLINZMANN/FUNK//

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