WDPN33 PGTW 231500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (NEOGURI) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.6N 153.3E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 740 NM EAST-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
25W (NEOGURI) WITH A REDEVELOPMENT OF ROBUST CENTRAL CONVECTION
OVER THE PAST 6 HOURS. A FIELD OF STRATOCUMULUS CLOUDS CAN BE SEEN
WRAPPING INTO THE SYSTEM ALONG THE WESTERN BOUNDARY OF 25W, SHOWING
AN INCREASING AMOUNT OF DRY AIR INTERACTING WITH THE VORTEX. A
231041Z METOP-C ASCAT PASS REVEALED A CORE OF STRONG WINDS (OVER 50
KTS) WITH A LARGE BAND OF GALE FORCE WINDS EXTENDING FAR TO THE
NORTH-NORTHWEST. ENVIRONMENTAL ANALYSIS INDICATES THAT 25W IS IN A
MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD
OUTFLOW ALOFT, LOW TO MODERATE (15-20 KTS) WESTERLY VERTICAL WIND
SHEAR, DRY AIR ENTRAINMENT, AND WARM (28-29 C) SEA SURFACE
TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE AFOREMENTIONED METOP-C ASCAT PASS. THE INITIAL
INTENSITY OF 75 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED
PRIMARILY ON THE AGENCY DVORAK CI ESTIMATES RANGING FROM 4.0-4.5.
CIMSS OBJECTIVE ESTIMATES ARE ANALYZED TO BE FAR TOO LOW, LIKELY
DUE TO THE WEAK CONVECTIVE STRUCTURE.

INITIAL WIND RADII BASIS: 231041Z METOP-C ASCAT SCATTEROMETER DATA

CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT WITH
COMPETING SUBTROPICAL RIDGES TO BOTH THE EAST AND WEST OF THE
SYSTEM.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 52 KTS AT 230758Z
   CIMSS ADT: 45 KTS AT 231130Z
   CIMSS AIDT: 56 KTS AT 231130Z
   CIMSS D-MINT: 55 KTS AT 230853Z
   CIMSS D-PRINT: 55 KTS AT 231130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE NORTH AND WEST

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: 25W IS FORECAST TO CONTINUE TRACKING GENERALLY
NORTHEASTWARD OVER THE NEXT 36 HOURS. NEAR TAU 36, THE EASTERN
RIDGE WILL BUILD AND EXTEND TO THE NORTH OF THE SYSTEM, DRIVING 25W
BACK WESTWARD THROUGH TAU 72. AROUND TAU 72, A SHORTWAVE TROUGH
WILL PROPAGATE EASTWARD AND BREAK DOWN THE RIDGE, ALLOWING THE
VORTEX TO RECURVE TO THE NORTHEAST THROUGH THE REMAINDER OF THE
FORECAST PERIOD. EXTRATROPICAL TRANSITION IS FORECAST TO BEGIN AT
TAU 96 AND COMPLETE AT TAU 120, AS 25W BECOMES EMBEDDED WITHIN THE
BAROCLINIC ZONE AND STRONG UPPER-LEVEL WINDS. REGARDING INTENSITY,
25W IS FORECAST TO WEAKEN AFTER TAU 24 THROUGH TAU 72 AS UPWELLING 
CONTINUES TO BE A FACTOR IN RESPONSE TO THE SLOW TRACK SPEEDS. 
ADDITIONALLY, DRY AIR WILL CONTINUE TO ENTRAIN INTO THE CORE OF THE 
SYSTEM, AIDING IN THE WEAKENING TREND. AS THE SYSTEM BEGINS TO SPEED 
UP AT TAUS 96 AND 120, BAROCLINIC FORCING AND ROBUST POLEWARD OUTFLOW 
WILL ALLOW 25W TO MARGINALLY REINTENSIFY AS EXTRATROPICAL TRANSITION 
ENSUES. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 72 WITH ALL MODELS DEPICTING THE WESTWARD
TURN AFTER TAU 36. HOWEVER, AFTER TAU 72, THE TIMING OF ACCELERATION 
NORTHEASTWARD HIGHLY DIFFERS BETWEEN MODELS. UKMET AND ECMWF ARE 
SLOWER WHILE THE VARIOUS AI MODELS AND GFS ARE CONSIDERABLY FASTER. 
AT TAU 120, THERE IS AROUND 850 NM OF ALONG-TRACK SPREAD, LENDING 
VERY LOW CONFIDENCE TO THE JTWC TRACK FORECAST AFTER TAU 72. 
INTENSITY GUIDANCE IS IN MODERATE AGREEMENT WITH ALL MODELS SHOWING 
GRADUAL WEAKENING AFTER TAU 24 THROUGH TAU 72. AFTER TAU 72, MODELS 
ARE A BIT SPLIT BETWEEN A STEADY INTENSITY AND REINTENSIFICAITON. GFS 
AND COAMPS-TC BOTH DEPICT REINTENSIFICATION WHILE HAFS-A KEEPS A 
STEADY INTENSITY. THE JTWC INTENSITY FORECAST SPLITS THE DIFFERENCE, 
CALLING FOR ONLY MARGINAL INTENSIFICATION AS 25W TRANSITIONS INTO AN 
EXTRATROPICAL CYCLONE.

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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