WDPN31 PGTW 071500 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (LINGLING) WARNING 
NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 071200Z0 TO 101200Z4 NOV 01.
   A. TROPICAL STORM (TS) 27W (LINGLING), LOCATED IN THE PHILIPPINE 
ISLANDS, HAS TRACKED WEST-NORTHWESTWARD AT 04 KNOTS DURING THE PAST 
SIX HOURS. THE WARNING POSITION IS BASED ON 071130Z2 INFRARED 
SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE 
CURRENT INTENSITY ESTIMATES OF 35 AND 45 KNOTS, AND SYNOPTIC DATA. 
ANIMATED INFRARED SATELLITE IMAGERY INDICATES THE SYSTEM HAS 
MAINTAINED GOOD ORGANIZATION AS IT PASSES THROUGH THE PHILIPPINE 
ISLANDS. WATER VAPOR IMAGERY DEPICTS GOOD OUTFLOW AND AN OUTFLOW 
CHANNEL ON THE POLEWARD SIDE.
    B. THE SUBTROPICAL RIDGE EXTENDS ALONG THE SOUTHERN COAST OF 
CHINA AND CONTINUES TO BE THE PRIMARY STEERING INFLUENCE FOR TS 27W. 
THE SUBTROPICAL RIDGE IS FORECAST TO BUILD EASTWARD BEFORE THE NEXT 
MID-LATITUDE TROUGH WEAKENS THE PATTERN BY THE END OF THE FORECAST 
PERIOD. A PERIPHERAL RIDGE SITUATED TO THE SOUTHEAST OF TS 27W IS 
FORECAST TO BUILD, INDUCING A MORE POLEWARD COMPONENT TO A GENERALLY 
WESTWARD TRACK. THEREFORE, THE SYSTEM IS FORECAST TO TRACK WESTWARD 
THEN WEST-NORTHWESTWARD AS THE RIDGE WEAKENS BY THE END OF THE 
FORECAST PERIOD. THE AVAILABLE DYNAMIC AIDS INCLUDE NOGAPS, COAMPS, 
GFDN, UK-MET OFFICE GLOBAL, NCEP AVIATION AND THE JMA GLOBAL AND 
TYPHOON MODELS. THE MODELS ARE IN FAIR AGREEMENT WITH A WEST-
NORTHWEST TRACK IN THE TROPICAL EASTERLIES SOUTH OF THE SUBTROPICAL 
RIDGE. OUR FORECAST IS BASED PERSISTENCE AND A BLEND OF ALL THE 
AVAILABLE MODELS. 
   C. TS 27W IS EXPECTED TO INTENSIFY OVER THE FORECAST PERIOD 
IN A REGION OF DIFFLUENT EASTERLIES SOUTH OF THE UPPER RIDGE AXIS.
   D. WIND RADII CRITERIA BASED ON CLIMATOLOGY. 
FORECAST TEAM: SMITH/MAYER/KENDALL/PIVIN/WEAVER/TON//
BT
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