WDPN32 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 32W (FUNG-WONG) WARNING 
NR 029//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1N 118.6E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 279 NM EAST-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM 32W (FUNG-WONG) WITH WIDESPREAD SHALLOW CONVECTION OBSCURING
THE LOW-LEVEL CIRCULATION CENTER (LLCC). AN 110152Z METOP-B ASCAT
IMAGE REVEALED GALE-FORCE WINDS ASSOCIATED WITH THE ENHANCED
NORTHWESTERLY SURGE EXTENDING ALL THE WAY THROUGH THE TAIWAN
STRAIT. THE ASCAT ALSO REVEALED THAT THE STRONGEST WINDS ARE
CONFINED TO A SWATH OF WESTERLY WINDS WITHIN THE SOUTHERN
SEMICIRCLE. ENVIRONMENTAL ANALYSIS INDICATES THAT 32W IS IN AN
UNFAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD OUTFLOW
AND WARM (27-28 C) SEA SURFACE TEMPERATURES, GREATLY OFFSET BY
MODERATE (15-20 KTS) SOUTHEASTERLY VERTICAL WIND SHEAR AND
SIGNIFICANT DRY AIR ENTRAINMENT. THE INITIAL POSITION IS PLACED
WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED MSI. THE INITIAL
INTENSITY OF 55 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY DVORAK FIXES AND CIMSS OBJECTIVE INTENSITY ESTIMATES LISTED
BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 110152Z METOP-B
ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE CENTERED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 56 KTS AT 110545Z
   CIMSS ADT: 65 KTS AT 110600Z
   CIMSS AIDT: 58 KTS AT 110600Z
   CIMSS D-PRINT: 48 KTS AT 110600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: NORTHWESTERLY SURGE FLOW INTRODUCING COLD, DRY
AIR TO THE VORTEX.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 32W IS FORECAST TO CONTINUE ROUNDING THE
WESTERN EXTENT OF THE SUBTROPICAL RIDGE THROUGH TAU 48 WITH A
GENERALLY NORTHEASTWARD TRACK. LANDFALL WITHIN THE SOUTHWESTERN
COAST OF TAIWAN IS EXPECTED TO OCCUR JUST AFTER TAU 24. THE
ENVIRONMENT WILL CONTINUE TO BE UNFAVORABLE, CAUSING 32W TO WEAKEN
THROUGH THE APPROACH TO TAIWAN. THE SYSTEM WILL THEN QUICKLY TRACK
ACROSS SOUTHERN TAIWAN AND EMERGE BACK OVER WATER. THE COMBINATION
OF EFFECTS FROM THE MOUNTAINOUS TERRAIN, INCREASING WESTERLY
VERTICAL WIND SHEAR, AND DRY AIR WILL FURTHER DETERIORATE THE
VORTEX. 32W IS THEN EXPECTED TO QUICKLY BECOME ABSORBED INTO THE
FORMING FRONTAL BOUNDARY NO LATER THAN TAU 72, NEAR OKINAWA. THE
WINDS ASSOCIATED WITH FUNG-WONG ARE FORECAST TO WEAKEN, HOWEVER,
GALE-FORCE WINDS ASSOCIATED WITH THE OVERALL FRONTAL BOUNDARY ARE
STILL POSSIBLE FOR OKINAWA. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 48 WITH A CROSS-TRACK SPREAD OF AROUND 80 NM. AFTER TAU
48, MODELS RAPIDLY BEGIN TO DIVERGE WITH DIFFERING REACTIONS TO
THE INTERACTION WITH THE FRONTAL BOUNDARY. SOME MODELS TURN THE
SYSTEM TOWARD THE SOUTHEAST WHILE OTHERS CONTINUE ON AN
EAST-NORTHEASTWARD TRACK. THE JTWC TRACK FORECAST IS PLACED CLOSE
TO THE MULTI-MODEL CONSENSUS THROUGH TAU 72 WITH MEDIUM CONFIDENCE.
INTENSITY GUIDANCE AGREES ON WEAKENING THROUGH TAU 36, BUT THEN
DISAGREES AFTERWARD. SOME MODELS DEPICT CONSISTENT WEAKENING WHILE
OTHERS MAINTAIN AROUND 40 KTS THROUGH TAU 60, LIKELY ACCOUNTING FOR
THE BACKGROUND SURGE FLOW. THE JTWC INTENSITY FORECAST CALLS FOR
CONSISTENT WEAKENING IN AN ATTEMPT TO ACCOUNT FOR WINDS ASSOCIATED
PRIMARILY WITH 32W. THE DISAGREEMENT AFTER LANDFALL IN TAIWAN
CAUSES THERE TO BE LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: LOW//
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