WDPN33 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (NEOGURI) WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.7N 153.3E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 737 NM EAST-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 25W
(NEOGURI) WITH INCREASINGLY DISORGANIZED CENTRAL CONVECTION
OBSCURING A STILL WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC).
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 222325Z 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 MEDIUM CONFIDENCE
BASED ON THE ANIMATED MSI. THE INITIAL INTENSITY OF 75 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED PRIMARILY ON THE AGENCY
DVORAK CI ESTIMATES RANGING FROM 4.0-5.0. CIMSS OBJECTIVE ESTIMATES
ARE ANALYZED TO BE FAR TOO LOW, LIKELY DUE TO THE WEAK CONVECTIVE
STRUCTURE.

INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 222325Z 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: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 78 KTS AT 230313Z
   CIMSS ADT: 51 KTS AT 230540Z
   CIMSS AIDT: 49 KTS AT 230540Z
   CIMSS D-MINT: 51 KTS AT 230313Z
   CIMSS D-PRINT: 51 KTS AT 230540Z

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: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE SYSTEM IS NOW FORECAST TO
COMPLETE EXTRATROPICAL TRANSITION NEAR TAU 120.

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 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. GFS AND
ECMWF ARE SLOWER WHILE THE VARIOUS AI MODELS ARE 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 THROUGH TAU 72. AFTER TAU 72, THE SLOWER MODELS (WHICH
INCLUDES HAFS-A) SHOW STRONGER REINTENSIFICATION DUE TO THE SYSTEM
INTERACTING WITH WARMER SEA SURFACE TEMPERATURES AND LESS VERTICAL
WIND SHEAR. THE JTWC INTENSITY FORECAST ONLY CALLS FOR MARGINAL
INTENSIFICATION DUE TO A FASTER RECURVE TIMELINE THAN THE MOST
INTENSE MODELS.

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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