WDPN31 PGTW 091500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W WARNING NR 11//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 091200Z DEC TO 141200Z DEC 2006.
   A. TYPHOON (TY) 25W (UTOR), LOCATED APPROXIMATELY 260 NM SOUTH-
EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 12
KNOTS OVER THE PAST SIX HOURS.
   B. TY 25W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROP-
ICAL RIDGE ANCHORED NORTHEAST OF LUZON. THE STORM IS EXPECTED TO
CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE INFLUENCE OF THIS
STEERING RIDGE THROUGH TAU 72. THE AVAILABLE DYNAMIC AIDS ARE IN
FAIR AGREEMENT WITH THIS SCENARIO WITH THE EXCEPTION OF JGSM, JTYM
AND EGRR, WHICH DEPICT A MORE EQUATORWARD TRACK DRIVEN BY STRONGER
RIDGING TO THE NORTH. THIS FORECAST IS BASED ON A CONSENSUS OF ALL
AVAILABLE DYNAMIC AIDS.
   C. TY 24W IS EXPECTED TO MAINTAIN INTENSITY OR WEAKEN ONLY
SLIGHTLY THROUGH TAU 24 UNDER THE COMPETING INFLUENCES OF LAND IN-
TERACTION AND GOOD UPPER LEVEL OUTFLOW. THE STORM IS THEN EXPECTED
TO INTENSIFY IN THE SOUTH CHINA SEA AT A SLIGHTLY LESS THAN CLIMA-
TOLOGICAL RATE BETWEEN TAU 24 AND TAU 72 AS CONTINUED GOOD UPPER
LEVEL OUTFLOW IS SOMEWHAT OFFSET BY ENTRAINMENT OF DRIER AIR FROM
THE ASIAN CONTINENT.
   D. CURRENT WIND RADII ARE BASED ON A 090956Z QUIKSCAT PASS AND
RECENT MICROWAVE SATELLITE IMAGERY. FORECAST WIND RADII ARE BASED
ON CLIMATOLOGY FOR AN AVERAGE-SIZED SYSTEM.
   E. IN THE EXTENDED PERIOD, A DEVELOPING MID-LATITUDE TROUGH IS
EXPECTED TO WEAKEN THE STEERING RIDGE SIGNIFICANTLY. UNCERTAINTY
REMAINS IN THE EXTENDED FORECAST TRACK, ALTHOUGH A MAJORITY OF THE
DYNAMIC AIDS, INCLUDING NOGAPS, GFS AND ECMWF, NOW SUGGEST A MORE
POLEWARD TRACK AFTER TAU 72. THE CURRENT FORECAST DEPICTS THE SYS-
TEM ENTERING A WEAK STEERING ENVIRONMENT IN THE COL AREA BETWEEN
THE CURRENT STEERING RIDGE AND A RIDGE TO THE WEST ANCHORED OVER
THE BAY OF BENGAL AFTER TAU 72. IN THIS ENVIRONMENT, THE STORM IS
EXPECTED TO INTENSIFY SLIGHTLY WITH ENHANCED POLEWARD OUTFLOW BUT
CONTINUE TO ENTRAIN DRY AIR INTRODUCED BY THE WESTERN RIDGE. NOGAPS
AND ECMWF ARE IN FAIR AGREEMENT WITH THIS SCENARIO, BUT GFS DEPICTS
ARE MORE AGRESSIVE RECURVATURE INTO THE MID-LATITUDE WESTERLIES.
THIS FORECAST IS BASED ON A CONSENSUS OF THESE EXTENDED FORECAST
MODELS.
FORECAST TEAM: DELTA//
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