WDPN31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (UTOR) WARNING NR 16//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 11W (UTOR), LOCATED APPROXIMATELY 346 NM SOUTHEASTWARD OF
HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER THE
PAST SIX HOURS. THE CURRENT POSITION IS BASED ON A RECENT PGTW 
INFRARED SATELLITE FIX AND A 37 GHZ, 121154Z SSMIS MICROWAVE 
SATELLITE IMAGE SHOWING A CLEAR LOW LEVEL EYE FEATURE. THE CURRENT 
INTENSITY OF 85 KNOTS IS CONSISTENT WITH A CONSENSUS OF DVORAK T-
NUMBER ESTIMATES FROM PGTW, RJTD, AND KNES. TY 11W CONTINUES TO 
TRACK ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE. 
THE SYSTEM IS STEADILY RECONSOLIDATING AFTER EMERGING OVER THE SOUTH 
CHINA SEA, WITH MULTIPLE DEEP CONVECTIVE BANDS SPIRALING INTO A 
DEVELOPING RAGGED EYE FEATURE EVIDENT IN RECENT INFRARED SATELLITE 
IMAGERY. TY 11W LIES SLIGHTLY EQUATORWARD OF AN UPPER LEVEL RIDGE 
AXIS, WITH STRONG WESTWARD AND MODERATE POLEWARD DIFFLUENCE ALOFT, 
AND DECREASING EASTERLY VERTICAL WIND SHEAR. 
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE 
PREVIOUS PROGNOSTIC REASONING BULLETIN.
   B. TY 11W WILL CONTINUE TRACKING WEST-NORTHWESTWARD OVER THE NEXT 
36 HOURS UNDER THE STEERING INFLUENCE OF THE CURRENT STEERING RIDGE. 
THE SYSTEM WILL TURN SLIGHTLY POLEWARD AFTER TAU 36 AS IT ENCOUNTERS 
A WEAKNESS IN THE STEERING RIDGE INDUCED BY A SHORTWAVE TROUGH 
PASSING FAR TO THE NORTH, AND IT IS EXPECTED TO MOVE INLAND NEAR 
ZHANJIANG, CHINA JUST PRIOR TO TAU 48. THEREAFTER, THE DISSIPATING 
CYCLONE SHOULD TURN WESTWARD UNDER THE INFLUENCE OF THE REBUILDING 
SUBTROPICAL RIDGE. SLOW INTENSIFICATION OVER THE NEXT 48 HOURS IS 
EXPECTED, AS UPPER-LEVEL DIFFLUENCE REMAINS FAVORABLE, BUT EASTERLY 
VERTICAL WIND SHEAR AND DECREASING ALONG-TRACK OCEAN HEAT CONTENT 
RENDERS SIGNIFICANT INTENSIFICATION UNLIKELY. HOWEVER, THERE IS A 
SLIGHT CHANCE THAT THE SYSTEM WILL INTENSIFY MORE THAN CURRENTLY 
FORECAST JUST PRIOR TO LANDFALL IF DEVELOPMENT OF THE AFOREMENTIONED 
WEAKNESS IN THE STEERING RIDGE OR INTERACTION WITH AN UPPER LEVEL 
LOW ANALYZED TO THE NORTHWEST ALLOWS A SUBSTANTIAL POLEWARD OUTFLOW 
CHANNEL TO DEVELOP. GIVEN THE RELATIVELY STRAIGHTFORWARD STEERING 
ENVIRONMENT AND GOOD AGREEMENT AMONG THE CONSENSUS MODELS, 
CONFIDENCE IN THE FORECAST TRACK THROUGH TAU 72 REMAINS HIGH. 
   C. TY 11W WILL DISSIPATE OVER LAND IN THE EXTENDED PERIOD, 
DROPPING BELOW THE WARNING THRESHOLD INTENSITY OF 25 KNOTS BY TAU 
96. THE NUMERICAL MODEL GUIDANCE, WITH THE EXCEPTION OF THE EASTWARD-
OUTLYING JAPANESE ENSEMBLE AND COAMPS-TC MODEL, IS IN GOOD AGREEMENT 
WITH THE TRACK FORECAST IN THE TAU 72 TO TAU 96 PERIOD, SO FORECAST 
TRACK CONFIDENCE REMAINS HIGH.//
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