WDPN31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.9N 141.4E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 394 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A MEDIUM-SIZED
SYMMETRICAL CYCLONE THAT HAS MAINTAINED ITS OVERALL CONVECTIVE AND
WRAP STRUCTURE AND A LARGE 40-NM BANDING EYE. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE BANDING EYE THAT WAS
CONCENTRIC WITH THE MICROWAVE EYE FEATURE IN THE 120611Z SSMIS
IMAGE. THE INITIAL INTENSITY OF 85KTS IS BASED ON AN OVERALL
ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS
THE SUSTAINED 6-HR CONVECTIVE AND WRAP STRUCTURE. ANALYSIS
INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VWS AND
MODERATE OUTFLOW OFFSET BY LOCALIZED LOW SST AND OHC VALUES DUE TO
OCEANIC UPWELLING.

INITIAL WIND RADII BASIS: AMSR2 WINDSPEED DATA.

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 76 KTS AT 120056Z
   CIMSS ADT: 82 KTS AT 120530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR INTRUSION FROM THE NORTHWEST.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TYPHOON LAN WILL CONTINUE ON ITS CURRENT TRACK
TOWARD CENTRAL HONSHU, JAPAN. AFTER TAU 48, IT WILL TRACK MORE
NORTHWARD AS THE STR RECEDES IN RESPONSE TO A MID-LATITUDE TROUGH
APPROACHING FROM THE NORTHWEST, MAKE LANDFALL NEAR MINAMISE, CREST
THE STR AXIS AROUND TAU 72 AS IT PASSES JUST TO THE EAST OF KYOTO,
EXIT INTO THE SEA OF JAPAN (SOJ), THEN ACCELERATE NORTHEASTWARD ON
THE POLEWARD SIDE OF THE STR. THE MARGINAL ENVIRONMENT WILL SUSTAIN
THE CURRENT INTENSITY OF 85KTS UP TO TAU 48; AFTERWARD, LAND
INTERACTION AND INCREASING VWS WILL REDUCE IT TO 65KTS BY TAU 72.
DESPITE THE RELATIVELY WARM SST IN THE SOJ, INCREASING VWS, THEN
INTERACTION WITH THE BAROCLINIC ZONE AS TY 07W BEGINS
EXTRA-TROPICAL TRANSITION AROUND TAU 96 WILL GRADUALLY ERODE IT TO
A 40-KT COLD CORE LOW BY TAU 120.  

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY GOOD AGREEMENT WITH
A GRADUAL AND EVEN SPREAD TO JUST 138NM BY TAU 72, THEN TO 213NM BY
TAU 120, LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST UP TO
TAU 72 THEN MEDIUM CONFIDENCE AFTERWARD. THERE IS MEDIUM CONFIDENCE
IN THE JTWC INTENSITY FORECAST UP TO TAU 72 THEN LOW AFTERWARD DUE
TO VARIABILITY INHERENT WITH EXTRA-TROPICAL TRANSITION.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
NNNN