Advisories

WDPN32 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (CHOI-WAN) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.6N 146.4E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 402 NM EAST-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE LARGE
CLOUD FIELD ASSOCIATED WITH TYPHOON (TY) 26W. THE SYSTEM HAS NOT
DEGRADED ALL THAT MUCH IN THE LAST SIX HOURS, CONSISTING OF
EXTENSIVE BANDING FEATURES ALONG THE PERIPHERY AND A COMPACT
CENTRAL DENSE OVERCAST. THE SMALL EYE REMAINS CLOUD-FILLED, AND THE
AREAL EXTENT OF CLOUD TOP TEMPERATURES COLDER THAN -70 DEGREES
CELSIUS HAS DECREASED. A 060228Z AMSR3 PASS REVEALED EROSION OF THE
UPPER-LEVEL EYEWALL OVER THE SOUTHEAST QUADRANT, WHILE THE
LOWER-LEVEL EYEWALL REMAINED INTACT, SURROUNDED BY EXTENSIVE
RAINBANDS IN ALL QUADRANTS. THE ENVIRONMENT IS MARGINAL,
CHARACTERIZED BY STRONG POLEWARD OUTFLOW ALOFT OFFSET BY MARGINALLY
WARM SEA SURFACE TEMPERATURES (SST) OF 26-27 DEGREES CELSIUS, LOW
OCEAN HEAT CONTENT (OHC), AND MODERATE VERTICAL WIND SHEAR (VWS).
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
CLOUD-FILLED EYE EVIDENT IN THE MSI. THE INITIAL INTENSITY HAS BEEN
LOWERED TO 85 KTS WITH MEDIUM CONFIDENCE, REFLECTING THE GRADUAL
WARMING OF CLOUD TOP TEMPERATURES. THIS ASSESSMENT IS SUPPORTED BY
THE CONSENSUS OF THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A SUBTROPICAL
RIDGE CENTERED NEAR 34N 163E

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.0 - 90 KTS
   CIMSS SATCON: 94 KTS AT 060259Z
   CIMSS ADT: 74 KTS AT 060610Z
   CIMSS AIDT: 88 KTS AT 060610Z
   CIMSS D-MINT: 81 KTS AT 060356Z
   CIMSS D-PRINT: 81 KTS AT 060610Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: TY 26W WILL ACCELERATE NORTHEASTWARD ALONG THE
NORTHWESTERN PERIPHERY OF THE STR AS IT BECOMES INCREASINGLY
EMBEDDED WITHIN THE MID-LATITUDE, DEEP-LAYER WESTERLIES. THE SYSTEM
WILL UNDERGO RAPID EXTRATROPICAL TRANSITION AS IT INTERACTS WITH A
MID-LEVEL TROUGH EXTENDING FROM KAMCHATKA TO HONSHU, BECOMING FULLY
EXTRATROPICAL NO LATER THAN TAU 36. THE SYSTEM WILL CROSS THE
26-DEGREE CELSIUS ISOTHERM BY TAU 12, WHILE VWS INCREASES
SIGNIFICANTLY. THESE CONDITIONS WILL GRADUALLY ERODE THE INNER CORE
AND RESULT IN WEAKENING THROUGH TAU 24. THEREAFTER, STRONG
BAROCLINIC FORCING WILL SUPPORT TYPHOON-FORCE WINDS THROUGH TAU 36
AS THE SYSTEM COMPLETES EXTRATROPICAL TRANSITION. THE WIND FIELD
WILL REMAIN EXPANSIVE AND PRODUCE VERY HIGH SEAS.

MODEL DISCUSSION: TRACK GUIDANCE IS IN EXCELLENT AGREEMENT WITH
VERY SMALL ALONG-TRACK AND CROSS-TRACK SPREAD AMONG THE DYNAMICAL
AND AI MODELS. FROM TAU 24 TO TAU 36, THE AI MODELS LIE ON THE
POLEWARD SIDE OF THE GUIDANCE ENVELOPE. THE JTWC FORECAST TRACK IS
VIRTUALLY UNCHANGED FROM THE PREVIOUS CYCLE AND IS BASED ON A BLEND
OF THE MULTI-MODEL CONSENSUS (CONW) AND THE MEAN OF THE AI MODELS.
HIGH CONFIDENCE IS ASSESSED DUE TO THE TIGHT CLUSTERING OF THE
AVAILABLE TRACK GUIDANCE. THE INTENSITY AIDS ARE ALSO IN GOOD
AGREEMENT, DEPICTING STEADY WEAKENING. THE JTWC INTENSITY FORECAST
IS SET WITH HIGH CONFIDENCE NEAR THE GFS SOLUTION, WHICH IS A TAD
HIGHER THAN THAT OF GOOGLE DEEPMIND.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
NNNN