WDPN31 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (BANYAN) 
WARNING NR 09//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 14W (BANYAN), LOCATED APPROXIMATELY 177 NM NORTHWEST OF 
WAKE ISLAND, HAS TRACKED NORTH-NORTHWESTWARD AT 07 KNOTS OVER THE 
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A 
TIGHTLY WOUND SYSTEM WITH COMPACT RING OF PERSISTENT DEEP 
CONVECTION AND A PINHOLE EYE FEATURE, LENDING HIGH CONFIDENCE IN 
THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 90 KNOTS 
AND IS BASED ON SUBJECTIVE DVORAK ESTIMATES RANGING OF T5.0 (90 
KNOTS) FROM ALL AGENCIES. UPPER-LEVEL OUTFLOW REMAINS ROBUST 
FEEDING INTO A SHORTWAVE TROUGH OFF TO THE EAST, AND A POINT-SOURCE 
ANALYZED DIRECTLY OVER THE SYSTEM. VERTICAL WIND SHEAR IS ALSO VERY 
LOW SUPPORTING DEVELOPMENT, AND TY 14W IS TRACKING OVER VERY WARM 
WATER TEMPERATURES AROUND 30 CELSIUS. CURRENTLY TY 14W IS TRACKING 
NORTH-NORTHWEST ALONG THE WESTERN BOUNDARY OF A DEEP-LAYERED 
SUBTROPICAL RIDGE (STR).       
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE. 
   B. TS 14W WILL TRACK POLEWARD OVER THE FORECAST PERIOD GUIDED BY 
THE CURRENT STEERING RIDGE. WARM SSTS WILL PERSIST WITH EXCELLENT 
OUTFLOW OVER THE NEXT 24 HOURS, AND TY 14W WILL CONTINUE TO 
INTENSIFY REACHING A PEAK INTENSITY OF 110 KNOTS. AROUND TAU 24 TO 
36 AN UPPER-LEVEL RIDGE IS FORECAST TO BUILD IN NORTH OF THE SYSTEM 
INTRODUCING SOME RESISTANCE TO POLEWARD OUTFLOW, THUS HALTING THE 
INTENSIFICATION TREND. AROUND TAU 48 A SHORTWAVE TROUGH WILL 
DEVELOP ERODING THE UPPER-LEVEL RIDGE AND INCREASING VERTICAL WIND 
SHEAR. EVENTUALLY THE TROUGH WILL CAPTURE TY 14W BY TAU 72 AND SSTS 
WILL COOL AS THE SYSTEM TRACKS POLEWARD.   
   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. DYNAMIC 
MODEL GUIDANCE SHOWS GENERAL AGREEMENT IN THE FORECAST PHILOSOPHY, 
BUT THERE IS STILL A DEGREE OF UNCERTAINTY AS THE SYSTEM ROUNDS THE 
STR AXIS AND ACCELERATES NORTHEASTWARD. BECAUSE OF THIS 
UNCERTAINTY, THERE IS OVERALL MODERATE CONFIDENCE IN THE FORECAST 
TRACK.//
NNNN