WDPN31 PGTW 201500 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W WARNING NR 7//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 201200Z5 TO 231200Z8 OCT 01.
   A. TROPICAL STORM (TS) 26W (PODUL), LOCATED APPROXIMATELY 760 NM 
EAST-SOUTHEAST OF GUAM, HAS BEEN TRACKING NORTH-NORTHEASTWARD AT 13 
KNOTS DURING THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 
201130Z7 INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED 
ON SATELLITE CURRENT INTENSITY ESTIMATES OF 45 KNOTS. ANIMATED 
INFRARED SATELLITE IMAGERY INDICATES THAT THE DEEP CONVECTION HAS 
BECOME MORE ORGANIZED OVER THE PAST SIX HOURS. THE 200 MB ANALYSIS 
AND ANIMATED WATER VAPOR IMAGERY REVEAL THAT TS 26W IS IN A WEAK 
VERTICAL WIND SHEAR ENVIRONMENT WITH GOOD OUTFLOW ALOFT.
   B. A LOW/MID LEVEL SUBTROPICAL RIDGE NORTH OF TS 26W IS EXPECTED 
TO CONTINUE WEAKENING THROUGH THE FORECAST PERIOD AS THE BASE OF A 
SHORTWAVE TROUGH EAST OF JAPAN TRACKS EASTWARD. MEANWHILE, THE NEAR-
EQUATORIAL RIDGE WILL BUILD SOUTH AND EXTEND EAST OF THE SYSTEM, 
RESULTING IN A NORTH-NORTHWESTWARD TRACK THROUGH 72 HOURS. THE 
AVAILABLE DYNAMIC AIDS OF NOGAPS, GEOPHYSICAL FLUID DYNAMICS-NAVY 
(GFDN), THE UKMET OFFICE GLOBAL (EGRR), AND THE JMA GLOBAL (JGSM) 
AND TYPHOON (JTYM) MODELS ARE IN FAIR AGREEMENT WITH TWO DISTINCT 
CLUSTERS. JGSM, NCEP AVIATION, AND JTYM INDICATE A WEAK MID-LEVEL 
RIDGE NORTH OF THE SYSTEM AT 48 HOURS AND TRACK THE SYSTEM 
NORTHEASTWARD INTO THE WEAKNESS THROUGH 72 HOURS. THE SECOND CLUSTER 
CONSISTING OF EGRR, GFDN, AND NOGAPS BUILD THE RIDGE TO THE NORTH, 
RESULTING IN A MORE NORTH-NORTHWESTWARD TRACK. DUE TO POSSIBLE 
COMPENSATING ERRORS IN THE MODEL ANALYSES, OUR FORECAST BLENDS 
PERSISTENCE WITH THE CONSENSUS OF THE AVAILABLE DYNAMIC MODELS.  
   C. TS 26W IS EXPECTED TO INTENSIFY AT A NEAR CLIMATOLOGICAL RATE 
AS IT TRACKS OVER WARM SEA SURFACE TEMPERATURES AND UNDERNEATH THE 
UPPER-LEVEL RIDGE AXIS. 
   D. WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZE 
TROPICAL CYCLONE. 
FORECAST TEAM: VILPORS/WAUGAMAN/SCOTT/SHERRY/LAM/KUMAGA//