WDPN31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.8N 137.5E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 237 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 37 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (HM9 CIRA PROXY VIS)
SHOWS TYPHOON (TY) LAN'S RAGGED EYE TIGHTENING OVER TIME, CONTRACTING 
FROM A 55NM DIAMETER TO 35NM IN JUST SIX HOURS.  THE CONVECTIVE 
CANOPY APPEARS TO HAVE INCREASED IN DEPTH (COOLER CLOUD TOPS ON HM9 
IR-BD IMAGERY) AND EXPANDED RADIALLY FROM THE CORE, OBSCURING THE 
PREVIOUSLY OBSERVED FLARING CONVECTIVE CELLS. STRONG POLEWARD OUTFLOW 
IS EVIDENT IN THE CIRRUS LAYER, WITH OUTFLOW RESTRICTED ELSEWHERE. 
GOES-H9 ANIMATED WATER VAPOR IMAGERY DEPICTS DRY AIR ALONG THE ENTIRE 
WESTERN PERIPHERY OF THE CIRCULATION, WHICH IS CORROBORATED BY 
SUBSTANTIAL CLEARING ON PROXYVIS TO THE WEST AND SOUTH OF THE STORM. 
THE SYSTEM REMAINS SYMMETRIC IN APPEARANCE WITH NARROW BANDING 
WRAPPING INTO THE LLCC OBSCURED BY THE DEEP CONVECTIVE TOPS. SSTS ARE 
ASSESSED TO BE 28-29 DEGREES CELSIUS. THE INITIAL POSITION IS PLACED 
WITH HIGH CONFIDENCE BASED ON A 140000Z RJTD RADAR FIX AND 
EXTRAPOLATION OF A 132204Z SSMS 37GHZ IMAGE. THE INITIAL INTENSITY OF 
85KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON GROWTH OF THE 
CONVECTIVE CANOPY AND IS SUPPORTED BY AGENCY DVORAK ESTIMATES (ALL 
T4.5). ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW 
VWS AND STRONG POLEWARD OUTFLOW OFFSET BY MODERATE TO LOW SST AND OHC 
VALUES.

INITIAL WIND RADII BASIS: PERSISTENCE AND SAR DATA

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 97 KTS AT 132330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 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: TYPHOON LAN WILL CONTINUE ON ITS CURRENT TRACK
TOWARD CENTRAL HONSHU, JAPAN, MAKING LANDFALL NEAR TAU 24. DURING
THIS PERIOD, SOME FURTHER SLIGHT INTENSIFICATION MAY OCCUR AS THE 
SYSTEM BEGINS TO PICK UP SPEED, MOVING AWAY FROM UPWELLED SEAS AND 
ROUNDING THE AXIS OF THE STR POSITIONED TO THE NORTHEAST. A WEAKENING 
PHASE IS EXPECTED AS THE SYSTEM TRACKS OVER CENTRAL JAPAN AND THE 
KYOTO REGION AND UNDERGOES THE EFFECTS OF LAND INTERACTION THROUGH 
TAU 36, AFTER WHICH THE SYSTEM IS FORECAST TO RETURN OVER WATER IN 
THE SEA OF JAPAN AT TROPICAL STORM INTENSITY.  AFTER TAU 36, THE 
SYSTEM WILL CONTINUE TO TRACK NORTHEASTWARD AROUND THE RIDGING TO THE 
EAST AND DRAMATICALLY ACCELERATE TOWARD THE NORTHEAST DUE TO A DEEP,
SHARP MIDLATITUDE TROUGH THAT IS EXPECTED TO DIG TO THE WEST. THE
SYSTEM IS ANTICIPATED TO COMPLETE EXTRATROPICAL TRANSITION BETWEEN
TAU 96 AND TAU 120, STARTING THE TRANSITION AS EARLY AS TAU 72.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH
CROSS-TRACK ERROR OF 40NM AT LANDFALL AND 167NM AT TAU 72, LENDING
HIGH CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST. DUE TO 
THE UNCERTAINTIES INHERENT WITH EXTRATROPICAL TRANSITION AND MID-
LATITUDE TROUGH INTERACTION TO THE WEST, THERE IS MEDIUM CONFIDENCE 
IN THE EXTENDED PORTION OF THE TRACK FORECAST.

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