WDPN32 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (FRANCISCO)     
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.8N 129.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 361 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 10W REMAINS EMBEDDED WITHIN THE NORTHEASTERN 
PERIPHERY OF A LARGE, APPROXIMATELY 650NM DIAMETER LOW PRESSURE AREA, 
WHICH IS FORECAST TO GRADUALLY DEEPEN AND STRENGTHEN INTO A MONSOON 
DEPRESSION WITH EXPANSIVE GALE FORCE WINDS OVER THE NEXT 24 TO 48 
HOURS. THIS COMPLEX SYNOPTIC PATTERN IS EVIDENT IN THE CIMSS TOTAL 
PRECIPITABLE WATER (TPW) ANIMATION, WITH MULTIPLE TROPICAL SYSTEMS 
ROTATING CYCLONICALLY ALONG THE PERIPHERY (10W, 11W AND INVEST 90W). 
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY 
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) POSITIONED ALONG 
THE NORTHWESTERN EDGE OF THE CONVECTIVE MASS, WHICH HAS BECOME MORE 
ASYMMETRIC AND FRAGMENTED OVER THE PAST FEW HOURS AS INVEST 90W GETS 
ABSORBED IN THE SOUTHERN FLANK OF THE SYSTEM IMPEDING INFLOW. THE 
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE MSI 
IMAGERY. ENVIRONMENTAL CONDITIONS ARE FAVORABLE, WITH ENHANCED POLEWARD 
OUTFLOW EVIDENT IN ANIMATED WATER VAPOR IMAGERY AND IMPROVING OUTFLOW 
OVER THE SOUTHWESTERN QUADRANT, LOW VERTICAL WIND SHEAR AND WARM (29-
30C) SST VALUES. THERE IS SOME PRESSURE ON THE WESTERN FLANK OF THE 
SYSTEM ASSOCIATED WITH AN UPPER-LEVEL LOW TO THE NORTHWEST. THE INITIAL 
INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE 
PGTW DVORAK ESTIMATE AS WELL AS RECENT ASCAT DATA. 

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE POSITIONED TO THE EAST 
AND NORTH, WITH LARGE CYCLONIC FLOW PATTERN, AND EXTENSIVE WESTERLIES 
FROM SOUTHEAST ASIA TO THE EAST PHILIPPINE SEA.   

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 39 KTS AT 230000Z
   CIMSS AIDT: 36 KTS AT 230000Z
   CIMSS D-MINT: 30 KTS AT 222108Z
   CIMSS D-PRINT: 28 KTS AT 230100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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: TS 10W IS FORECAST TO CONTINUE TO TRACK
NORTH-NORTHWESTWARD TO NORTHWESTWARD AROUND THE NORTHEASTERN AND
NORTHERN PERIPHERY OF THE LARGE LOW PRESSURE AREA OR DEVELOPING
MONSOON DEPRESSION THROUGH TAU 48. THE SYSTEM IS EXPECTED TO
INTENSIFY SLOWLY TO A PEAK OF 40 KNOTS BY TAU 12, MAINTAINING 40
KNOTS THROUGH TAU 48. TS 10W IS EXPECTED TO MAINTAIN TROPICAL
CHARACTERISTICS, WITH A RADIUS OF MAXIMUM WINDS UNDER 100NM AND
CORE CONVECTION AT LEAST THROUGH TAU 36. AFTER TAU 36, AS THE
SYSTEM APPROACHES OKINAWA, IT WILL BEGIN TO GRADUALLY MERGE INTO
THE MONSOON DEPRESSION CENTER, WITH EXTENSIVE GALE FORCE WINDS
DISPLACED OVER THE EASTERN AND NORTHERN FLANK OF THE SYSTEM. THESE
GALE FORCE WINDS ARE EXPECTED TO EXTEND AS FAR AS 175NM OVER THE
NORTHEAST QUADRANT. THE EXACT TIMING OF THIS TRANSITION IS
DIFFICULT TO PINPOINT BUT COULD OCCUR EARLIER. HOWEVER, THE OVERALL
WIND IMPACTS TO OKINAWA WILL REMAIN CONSISTENT REGARDLESS.    

MODEL DISCUSSION: AS DISCUSSED EARLIER, THIS SYNOPTIC PATTERN IS
EXTREMELY COMPLEX AND CHALLENGING. THEREFORE, JTWC TRACK CONFIDENCE
REMAINS LOW. DETERMINISTIC GUIDANCE IS IN FAIR AGREEMENT, WITH A
130NM CROSS-TRACK SPREAD AT TAU 36. THE BULK OF THE TRACKERS ARE
SOUTH OF THE JTWC FORECAST TRACK AND CONTINUE TO TRACK THE BROAD
MONSOON DEPRESSION CENTER. THE JTWC TRACK FORECAST CONTINUES TO
FAVOR THE ECMWF AND ECENS TRACKERS BUT ARE SPECIFICALLY TRACKING A
DISCRETE LOW-LEVEL VORTICITY MAXIMUM WITHIN THE NORTHERN PORTION OF
THE BROAD LOW PRESSURE CENTER. THIS PREFERENCE FOR THE ECMWF MODELS
IS BASED ON THE SUPERIOR PERFORMANCE OF THE MODEL IN THE 
DEVELOPMENT STAGE AND INITIAL TRACK TO THIS POINT. THE JTWC TRACK
FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, WITH SOME
MINOR ADJUSTMENTS BASED ON THE 230000Z INITIAL POSITION. AS A 
CONSEQUENCE, THE CPA TO KADENA HAS INCREASED FROM 78NM TO 97NM. DUE TO 
THE NATURE OF THE SYSTEM AND ITS EXPECTED EVOLUTION OVER THE NEXT FEW 
DAYS, SHIFTS IN BOTH THE INITIAL POSITION AND TRACK ARE VERY LIKELY. 
THE 221200Z ECENS SHOWS A SIMILAR SWATH OF SOLUTIONS OVER AND TO THE 
SOUTH OF OKINAWA, WITH A GENERAL TRACK TOWARD EASTERN CHINA SOUTH OF 
30N LATITUDE. THE 221800Z GEFS ENSEMBLE INDICATES MORE UNCERTAINTY IN
THE TRACK ESPECIALLY AFTER PASSING WEST OF OKINAWA. 

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