WDPN33 PGTW 220900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (NEOGURI) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.2N 151.8E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 379 NM NORTH-NORTHWEST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS WARMING
CLOUD TOPS AS TYPHOON (TY) 25W HAS STRUGGLED TO COMBAT UPWELLING
AND HIGH VERTICAL WIND SHEAR OVER THE LAST SIX HOURS. AN
UPPER-LEVEL TROUGH IS STRONGLY ENHANCING OUTFLOW, BUT INCREASING
SHEAR UNFAVORABLY AND ERODING THE WESTERN PERIPHERY OF THE SYSTEM.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED ANIMATED EIR. THE INITIAL INTENSITY OF 105 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: COMPETING STEERING ENVIRONMENT BETWEEN
TWO SUBTROPICAL RIDGES

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 140 KTS AT 220531Z
   CIMSS ADT: 104 KTS AT 220540Z
   CIMSS AIDT: 103 KTS AT 220540Z
   CIMSS D-MINT: 146 KTS AT 220505Z
   CIMSS D-PRINT: 138 KTS AT 220640Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: TY 25W WILL REMAIN IN A COMPLEX AND COMPETING
STEERING ENVIRONMENT BETWEEN TWO SUBTROPICAL RIDGES TO THE EAST AND
WEST. WHILE THE TRACK FORECAST CAPTURES A SLOW EAST-NORTHEASTWARD
MOTION, IT WILL BE IRREGULAR AS THE TWO RIDGES GRAPPLE WITH ONE
ANOTHER. ERRATIC TRACK MOVEMENT SUCH AS LOOPING OR DOUBLING BACK
MAY OCCUR BETWEEN TAUS AND IS NOT CAPTURED IN THE WARNING GRAPHIC.
AFTER TAU 48, TY 25W WILL COME UNDER THE PRIMARY STEERING OF THE
RIDGE TO THE EAST AS AN UPSTREAM DEEP-LAYER TROUGH ERODES THE RIDGE
TO THE WEST. A CURVE AFTER TAU 96 WILL OCCUR AS THE TROUGH
PROPAGATES EASTWARD, ERODING THE EASTERN RIDGE AND ALLOWING THE
TROUGH TO THE WEST TO BECOME THE PRIMARY STEERING THROUGH THE END
OF THE FORECAST. WHILE DEPICTED ON THE WARNING GRAPHIC AS A SMOOTH
S-SHAPE, THERE IS STILL A HIGH PROBABILITY OF ERRATIC TRACK MOTION
BETWEEN TAUS. THE APPROACHING MAJOR SHORTWAVE TROUGH WILL INCREASE
VERTICAL WIND SHEAR UNFAVORABLY FOR THE NEXT 48 HOURS, ERODING THE
CYCLONE FROM THE WEST. ADDITIONALLY, SLOW TRACK MOTION AND
UPWELLING WILL PREVENT TY 25W FROM ACCESSING AN APPROPRIATE HEAT
SOURCE AND WILL ALSO LEAD TO THE CONTINUOUS WEAKENING THROUGH THE
END OF THE FORECAST. GIVEN THE SLOW MOTION, THE THERMAL BOUNDARY
REMAINS TO THE NORTH OF THE TYPHOON, AND TRANSITION IS NOT EXPECTED
DURING THE FORECAST PERIOD. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN SLIGHTLY
BETTER AGREEMENT AND NO LONGER INDICATES A BIFURCATION SCENARIO,
HOWEVER, THE COMPLEXITY OF THE SYNOPTIC ENVIRONMENT PRODUCES PEAKY
MODEL SOLUTIONS AND A LOT OF VARIATION. GIVEN THE CONTINUED
UNCERTAINTY OF THE TRACK GUIDANCE, THE JTWC TRACK FORECAST IS MADE
WITH LOW CONFIDENCE. THE INTENSITY GUIDANCE IS IN MUCH BETTER
AGREEMENT AND MAKES SENSE THAT THERE IS CONSISTENT WEAKENING,
MOSTLY DUE TO UPWELLING, FOR THE ENTIRETY OF THE FORECAST PERIOD.

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