WDPN33 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (NEOGURI) WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.7N 151.8E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 241 NM NORTH-NORTHWEST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE EYE
FEATURE WITH THE EYEWALL BREAKING DOWN ON THE NORTHERN PERIPHERY.
THE TRACK MOTION HAS SLOWED SLIGHLY OVER THE LAST SIX HOURS AS
TYPHOON (TY) 25W HAS BEGUN TO CURVE NORTHWESTWARD IN A COMPLEX
STEERING ENVIRONMENT. A 210739Z F-17 SSMIS 91GHZ IMAGE REVEALS THAT
THE EYEWALL HAS BROKEN DOWN ALONG THE NORTHERN PERIPHERY OF THE
SYSTEM. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON THE AFOREMENTIONED ANIMATED MSI. THE INITIAL INTENSITY OF 125
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY AND
OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A COMPETING STEERING ENVIRONMENT
BETWEEN TWO SUBTROPICAL RIDGES TO THE EAST AND WEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 125 KTS AT 210322Z
   CIMSS ADT: 122 KTS AT 210540Z
   CIMSS AIDT: 121 KTS AT 210540Z
   CIMSS D-MINT: 118 KTS AT 210322Z
   CIMSS D-PRINT: 126 KTS AT 210700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: THE STEERING ENVIRONMENT WILL BECOME
INCREASINGLY COMPLEX RESULTING IN IRREGULAR S-SHAPED TRACK MOTION
THROUGHOUT THE FORECAST PERIOD. FOR THE NEXT 36 HOURS, TY 25W WILL
CURVE NORTHEASTWARD SLOWLY AS THE SUBTROPICAL RIDGE TO THE WEST
BUILDS. AN UPSTREAM DEEP-LAYER TROUGH WILL SLIGHTLY BREAK DOWN THE
RIDGE TO THE WEST AT TAU 72, CAUSING THE SYSTEM TO CURVE NORTHWARD
BETWEEN TAU 72-120. THE DEEP-LAYER TROUGH WILL CAUSE THE SYSTEM TO
BECOME BAROCLINIC AND GRADUALLY UNDERGO EXTRATROPICAL TRANSITION
THROUGH THE END OF THE FORECAST PERIOD. THE SYSTEM IS STILL
ANTICIPATED TO SLIGHTLY INTENSIFY TO A PEAK OF 130KTS AT TAU 12
WHILE IN A FAVORABLE ENVIRONMENT. AS THE TRACK SPEED SLOWS,
SIGNIFICANT UPWELLING OF COOL WATER IS EXPECTED TO DEPLETE THE
OCEAN HEAT CONTENT BELOW, RESULTING IN A WEAKENING TREND TO 70KTS
BY TAU 120. THE APPROACHING TROUGH WILL INCREASE VERTICAL WIND
SHEAR AND PREVENT TY 25W FROM DEVELOPING IN ANY TROPICAL MANNER.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE HAS A LARGE
BIRFURCATION OF MODEL SOLUTIONS DEPENDING SOLELY ON THE STRENGTH OF
THE RIDGE TO THE WEST AND WHETHER THE UPSTREAM TROUGH
EFFECTIVELY BREAKS IT DOWN. IF THE RIDGE IS NOT BROKEN DOWN, THERE
ARE ALTERNATE SCENARIOS WHERE THE SYSTEM REMAINS IN A
QUASI-STATIONARY PERIOD FOR LONGER OR EVEN TRACKS TO THE SOUTHWEST
RATHER THAN NORTHEAST. THE INTENSITY GUIDANCE IS EQUALLY AS SPREAD
AND IS TIED DIRECTLY TO THE TRACK UNCERTAINTY.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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