WDPN31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.3N 136.9E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 228 NM SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION, AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (GOES H-8 PROXY VIS) SHOWS
A MEDIUM-SIZED SYMMETRICAL CYCLONE THAT HAS MAINTAINED ITS OVERALL
CONVECTIVE AND WRAP STRUCTURE WITH A LARGE 30X40-NM BANDING EYE,
EXPOSING A RAGGED AND IRREGULAR BUT DEFINED LOW LEVEL CIRCULATION
CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE EXPOSED LLCC FEATURE. THE INITIAL INTENSITY OF 85KTS
IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON A 140340Z AMSR2
WINDSPEED GRAPHIC, SUPPORTED BY AUTOMATED DVORAK ESTIMATES, AND
REFLECTS THE SUSTAINED STRUCTURE. ANALYSIS INDICATES A MARGINAL
ENVIRONMENT WITH LOW VWS AND MODERATE OUTFLOW OFFSET BY LOCALIZED
LOW SST AND OHC VALUES DUE TO OCEANIC UPWELLING AND DRY AIR
INTRUSION.

INITIAL WIND RADII BASIS: AMSR2 WINDSPEED GRAPHIC.

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


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 86 KTS AT 140400Z
   CIMSS ADT: 92 KTS AT 140640Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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
NORTHWESTWARD TRACK AND MAKE LANDFALL JUST BEFORE TAU 12 OVER
WAKAYAMA PREFECTURE THEN INLAND JUST TO THE WEST OF KYOTO BY TAU
24. AFTERWARD, IT WILL TRACK MORE NORTHWARD AS THE STR RECEDES IN 
RESPONSE TO A MID-LATITUDE TROUGH APPROACHING FROM THE NORTHWEST, EXIT 
INTO THE SEA OF JAPAN (SOJ), CREST THE STR AXIS BY TAU 36, THEN 
ACCELERATE NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR, CLIPPING THE 
NORTHERN TIP OF HOKKAIDO JUST AFTER TAU 72 AND BACK INTO THE PACIFIC 
OCEAN BY TAU 96. THE MARGINAL ENVIRONMENT WILL BECOME UNFAVORABLE WITH 
DRY AIR INTRUSION, INCREASING VWS, THEN LAND INTERACTION REDUCING IT 
TO 65KTS BY TAU 24. DESPITE THE RELATIVELY WARM SST IN THE SOJ, 
INCREASING VWS, THEN INTERACTION WITH THE BAROCLINIC ZONE AS TY 07W 
BEGINS EXTRA-TROPICAL TRANSITION BY TAU 72, IT WILL GRADUALLY ERODE TO 
A 45-KT COLD CORE LOW BY TAU 96.  


MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY GOOD AGREEMENT WITH
A GRADUAL AND EVEN SPREAD TO JUST 116NM BY TAU 72, LENDING HIGH
CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST. AFTERWARD,
THE MODELS SPREAD OUT TO 388NM BY TAU 96. THIS PLUS THE
UNCERTAINTIES INHERENT WITH EXTRA-TROPICAL TRANSITION LENDS ONLY
MEDIUM CONFIDENCE IN THE EXTENDED PORTION OF THE TRACK FORECAST.
THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST UP TO TAU
72 THEN LOW AFTERWARD FOR THE SAME REASON. 

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