WDPN32 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (PODUL) WARNING NR 
019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.0N 130.9E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 371 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED INFRARED SATELLITE IMAGERY SHOWS COOLING CLOUD TOPS
DEVELOPING OVER THE LOW-LEVEL CIRCULATION CENTER OF TROPICAL STORM
16W, INDICATING STRENGTHENING CONVECTION. THIS DEEP CONVECTION IS
PERSISTING DESPITE HIGH VERTICAL WIND SHEAR FROM THE NORTH. WATER
VAPOR IMAGERY ALSO REVEALS UPPER-LEVEL DIFFLUENCE, WHICH IS A
FAVORABLE CONDITION FOR STORM DEVELOPMENT. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE DUE TO THE INABILITY TO LOCATE THE 
OBSCURED LOW-LEVEL CIRCULATION CENTER IN ANIMATED EIR AND A LACK OF 
RECENT MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 55 KNOTS IS 
ASSESSED WITH MEDIUM CONFIDENCE, BASED ON THE AGENCY AND OBJECTIVE 
FIXES LISTED BELOW. HOWEVER, THE RECENT INCREASE IN CONVECTION OVER 
THE PAST SIX HOURS SUGGESTS THAT THE STORM IS ON AN INTENSIFYING 
TREND.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 57 KTS AT 111017Z
   CIMSS ADT: 43 KTS AT 111140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 30+ KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL STORM 16W IS EXPECTED TO CONTINUE ON
A WEST-NORTHWESTWARD TRACK, STEERED BY A SUBTROPICAL RIDGE TO THE
NORTH. HOWEVER, THE STORM MAY EXHIBIT IRREGULAR MOTION JUST BEFORE
MAKING LANDFALL ON THE EASTERN COAST OF TAIWAN. THIS IS DUE TO THE
KNOWN TRACK DEFLECTION CAUSED BY THE CENTRAL MOUNTAIN RANGE (CMR),
WHICH CAN INDUCE VORTICITY AND LEAD TO UNUSUAL LOOPING OR CURVING
BEHAVIOR IN APPROACHING TROPICAL CYCLONES. AFTER PASSING OVER
TAIWAN AND THE TAIWAN STRAIT, THE STORM WILL MAKE A FINAL LANDFALL
ON MAINLAND CHINA. THE ENVIRONMENT FOR DEVELOPMENT WILL REMAIN
MARGINALLY FAVORABLE OVER THE NEXT 36 HOURS. WHILE WARM SEA SURFACE
TEMPERATURES AND MODERATELY DIFFLUENT UPPER-LEVEL FLOW ARE
FAVORABLE, PERSISTENT 25-30KT VERTICAL WIND SHEAR FROM AN
ENHANCED UPPER-LEVEL RIDGE TO THE NORTH WILL RESTRICT THE RATE OF
INTENSIFICATION. TS 16W IS EXPECTED TO REACH A PEAK INTENSITY OF
75KTS. AFTER 36 HOURS, THE UPPER-LEVEL ENVIRONMENT WILL BECOME MORE
STREAMLINED, AND THE STORM WILL INTERACT MORE SIGNIFICANTLY WITH
THE ENHANCED FLOW, INITIATING A WEAKENING TREND. THIS WEAKENING
WILL ACCELERATE AFTER LANDFALL ON TAIWAN AS THE VERTICAL STRUCTURE
IS DISRUPTED BY THE MOUNTAINOUS TERRAIN OF THE CMR. TS 16W WILL
RE-EMERGE OVER THE TAIWAN STRAIT INTO AN ENVIRONMENT OF HIGH SHEAR
AND LOW OCEAN HEAT CONTENT BEFORE ITS SECOND AND FINAL LANDFALL ON
MAINLAND CHINA. THE MOUNTAINOUS TERRAIN OF TAIWAN WILL ULTIMATELY
LEAD TO DISSIPATION OF TS 16W BY TAU 72.


MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TS 16W WILL TRACK NORTHWESTWARD FOR THE REMAINDER OF THE
FORECAST PERIOD. THE CROSS-TRACK SPREAD AT THE END OF THE FORECAST
IS 118NM. THE INTENSITY GUIDANCE IS HIGHLY SENSITIVE TO SLIGHT
DEVIATIONS IN THE TRACK. THE TRACK SOLUTIONS LYING SOUTH OF THE
JTWC MULTI-MODEL CONSENSUS DEVELOP MORE THAN THE SOLUTIONS LYING
NORTH DUE TO LESS INTERACTION WITH ENHANCED UPPER-LEVEL FLOW, HIGHER 
SHEAR, AND DRIER AIR. THE CONFIDENCE FOR THE INTENSITY FORECAST IS 
LESS CONFIDENT THAN THE NEAR-TERM DUE TO THE SLIGHT DEVIATIONS IN THE 
TRACK GUIDANCE.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: LOW//
NNNN