WDPN33 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (CO-MAY)       
WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.3N 127.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 13 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH
SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. HOWEVER, AFTER
THE LLCC APPROACHED KADENA AIR BASE NEAR 280000Z, THE LLCC QUICKLY
BEGAN LOOPING CYCLONICALLY EAST OF KADENA AIR BASE. SURFACE WINDS
AT KADENA AIR BASE HAVE MAINTAINED AT 10-15 KNOTS SUSTAINED SINCE
272100Z, WITH SLP NEAR 988MB. SURFACE OBSERVATIONS OVER THE RYUKYU
ISLANDS HAVE REMAINED FAIRLY UNIMPRESSIVE, WITH MAXIMUM WINDS OF 26
KNOTS (10-MINUTE AVERAGE) CURRENTLY REPORTED AT KASARI (28.4N
129.7E) AND LESS THAN 20 KNOTS OVER OKINAWA. RECENT ASCAT DATA
INDICATES STRONGER NEAR GALE FORCE WINDS ASSOCIATED WITH THE DEEP
CONVECTIVE BANDING DISPLACED TO THE EAST OF OKINAWA. ANIMATED RADAR
IMAGERY SHOWS WEAK CURVED BANDS JUST NORTH OF OKINAWA, WITH THE
PRIMARY CONVECTIVE BAND DISPLACED TO THE EAST AND SOUTH. ANIMATED
WATER VAPOR IMAGERY REVEALS AN UPPER LOW POSITIONED TO THE WEST,
WHICH IS HINDERING CONVECTIVE DEVELOPMENT OVER THE WESTERN
SEMICIRCLE, WITH ROBUST EASTWARD AND EQUATORWARD OUTFLOW FUELING
THE PERSISTENT DEEP CONVECTION OVER THE EASTERN SEMICIRCLE. THE
INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE AGENCY DVORAK ESTIMATES AS WELL AS THE CIMSS ADT AND
AIDT OBJECTIVE ESTIMATES. THE 280046Z ASCAT-C BULLS-EYE IMAGE
SUPPORTS THE INITIAL POSITION AND SHOWS A BAND OF 25-30 KNOT WINDS
TO THE EAST AND A MORE EXTENSIVE REGION OF 30-35 KNOT WINDS
DISPLACED OVER 90NM TO THE NORTH.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT, WITH A
LOW- TO MID-LEVEL SUBTROPICAL RIDGE POSITIONED TO THE NORTH AND
NEAR-EQUATORIAL RIDGE TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 29 KTS AT 280010Z
   CIMSS AIDT: 35 KTS AT 280010Z
   CIMSS D-MINT: 30 KTS AT 272136Z
   CIMSS D-PRINT: 28 KTS AT 280100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG EASTWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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: AFTER COMPLETING THE CYCLONIC LOOP, TS 11W IS
FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD TO NORTHWESTWARD
THROUGH TAU 48 ALONG THE SOUTHERN PERIPHERY OF THE DOMINANT
STEERING INFLUENCE TO THE NORTH. GRADUAL INTENSIFICATION IS
EXPECTED AS THE SYSTEM MOISTENS AND DRY AIR ENTRAINMENT DECREASES.
ADDITIONALLY, THE UPPER LOW TO THE WEST IS EXPECTED TO WEAKEN AND
SHIFT SOUTHWESTWARD OVER TAIWAN, WHICH WILL ENHANCE POLEWARD
OUTFLOW. AS THE SYSTEM TRACKS WESTWARD OVER THE NEXT 12 TO 24
HOURS, THE NEAR GALE FORCE WINDS ALONG THE EASTERN FLANK MAY SHIFT
WESTWARD AND IMPACT OKINAWA. AFTER TAU 48, THE SYSTEM WILL RECURVE
POLEWARD OVERLAND, WITH STEADY WEAKENING AND DISSIPATION BY TAU
120.   

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT
THROUGH TAU 36, WITH A 90 NM CROSS-TRACK SPREAD IN THE GUIDANCE AT
TAU 36. THE 271800Z GEFS AND ECENS RUNS INDICATE CONSIDERABLE
UNCERTAINTY IN TRACK OVER THE NEXT 48 HOURS, WITH MEDIUM OVERALL 
CONFIDENCE IN THE JTWC FORECAST TRACK. THERE IS MEDIUM CONFIDENCE IN 
THE JTWC INTENSITY FORECAST, WITH RELIABLE INTENSITY GUIDANCE SHOWING 
A LARGE SPREAD, RANGING FROM 29 TO 53 KNOTS THROUGH TAU 36. AFTER THE 
FORECAST PERIOD, THERE IS LOW PROBABILITY THAT THE REMNANTS MAY TRACK 
BACK OVER THE WEST SEA. HOWEVER, UPPER-LEVEL WESTERLIES OVER THE WEST 
SEA AND THE KOREAN PENINSULA WILL LIMIT RE-DEVELOPMENT.       

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW
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