WDPN31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (BANYAN) 
WARNING NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 14W (BANYAN), LOCATED APPROXIMATELY 115 NM 
WEST-NORTHWEST OF WAKE ISLAND, HAS TRACKED NORTH-NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS A CENTRAL DENSE OVERCAST FEATURE WITH A FORMATIVE 
EYE, WHICH PROVIDES EXCELLENT SUPPORT FOR THE INITIAL POSITION. 
ANIMATED WATER VAPOR IMAGERY DEPICTS GOOD OVERALL OUTFLOW, 
PARTICULARLY OVER THE EASTERN SEMI-CIRCLE DUE TO THE PROXIMITY OF 
THE TUTT TO THE EAST. THIS FAVORABLE OUTFLOW PATTERN HAS SPURRED THE 
SHARP IMPROVEMENT IN STRUCTURE AND INCREASE IN THE INITIAL INTENSITY 
ASSESSMENT TO 60 KNOTS, WHICH IS BASED ON DVORAK INTENSITY ESTIMATES 
OF T3.5 (55 KNOTS) FROM ALL AGENCIES AND A 121006Z SATCON ESTIMATE 
OF 59 KNOTS. TS 14W IS TURNING POLEWARD ALONG THE SOUTHWESTERN 
PERIPHERY OF A SUBTROPICAL STEERING RIDGE TOWARD THE BASE OF AN 
APPROACHING MID-LATITUDE TROUGH TO THE NORTHWEST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE. 
   B. TS 14W WILL TRACK INCREASINGLY POLEWARD OVER THE NEXT 12 HOURS 
AS IT TRACKS ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE 
(STR), TOWARD THE BASE OF AN UPPER-LEVEL TROUGH CURRENTLY ANALYZED 
TO THE NORTHWEST OF THE SYSTEM. GENERALLY POLEWARD MOTION IS 
EXPECTED TO CONTINUE THROUGH TAU 72, WHEN THE SYSTEM WILL BEGIN TO 
INTERACT DIRECTLY WITH A SECOND TROUGH APPROACHING FROM THE 
NORTHWEST. STEADY INTENSIFICATION IS EXPECTED FOR THE NEXT 36 HOURS 
AS THE CYCLONE PASSES OVER VERY WARM WATER WHILE MAINTAINING A 
FAVORABLE UPPER-LEVEL OUTFLOW PATTERN. SIGNIFICANT WEAKENING IS 
ANTICIPATED AFTER TAU 60 AS THE SYSTEM BEGINS TO TRACK OVER COOLER 
SST AND ENCOUNTER INCREASING VERTICAL WIND SHEAR.
   C. IN THE EXTENDED PERIOD, TS 14W WILL ACCELERATE NORTH-
NORTHEASTWARD TO NORTHEASTWARD AS IT ROUNDS THE NORTHWEST PERIPHERY 
OF THE STR AND BEGINS TO INTERACT WITH THE MIDLATITUDE WESTERLIES. 
TS BANYAN SHOULD COMPLETE EXTRA-TROPICAL TRANSITION NEAR TAU 96 AS 
IT BECOMES EMBEDDED IN STRONG MIDLATITUDE WESTERLY FLOW. NUMERICAL 
MODEL GUIDANCE REMAINS IN FAIR AGREEMENT WITH SIGNIFICANT 
DIFFERENCES IN THE TIMING OF THE RE-CURVE AND TRACK SPEEDS, 
THEREFORE, THERE IS MODERATE OVERALL CONFIDENCE IN THE JTWC FORECAST 
TRACK.//
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