WDPN31 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.2N 138.9E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 255 NM NORTHWEST OF CHICHI JIMA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE
TYPHOON STRENGTH CIRCULATION, WITH A ROUGHLY 76NM QUASI-EYE FEATURE
IN THE CENTER WHERE THE CORE CONVECTION HAS COLLAPSED. A RECENT
130556Z SSMIS 89GHZ COLOR COMPOSITE MICROWAVE IMAGE SHOWS A THIN
FRAMEWORK OF DEEP CONVECTION COMPRISING THE EYE WALL AND FRAIL
BANDING FEATURES. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON MSI AND SSMIS IMAGERY. THE INITIAL INTENSITY OF
70 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGENCY DVORAK
AND AUTOMATED FIXES GENERALLY INDICATING 70-75 KTS WITH A FEW
OUTLIERS TOWARDS 80KTS SUCH AS CIMSS SATCON AND ADT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 80 KTS AT 130034Z
   CIMSS ADT: 84 KTS AT 130540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON 07W (LAN) IS FORECAST TO CONTINUE
TRACKING GENERALLY NORTHWESTWARD OVER THE NEXT 36 HOURS. DURING
THAT TIME, IMPROVING OCEAN HEAT CONTENT AND LOW VERTICAL WIND SHEAR
MAY FUEL MARGINAL INTENSIFICATION AS THE SYSTEM APPROACHES JAPAN.
JUST AFTER TAU 36 AND THROUGH TAU 48, 07W WILL CROSS THE ISLAND OF
HONSHU AND QUICKLY EXIT INTO THE SEA OF JAPAN. AS THE SYSTEM ROUNDS
THE STR AXIS, TRACK SPEEDS WILL GREATLY INCREASE AS THE SYSTEM IS
DIRECTED NORTHEASTWARD. BY TAU 72, THE SYSTEM WILL BEGIN TO
INTERACT WITH AN UPPER-LEVEL TROUGH OVER NORTHEASTERN CHINA AND A
COOLER AIR MASS, WHICH IS EXPECTED TO INITIATE EXTRATROPICAL
TRANSITION (ETT). THIS ETT IS ANTICIPATED TO COMPLETE BY TAU 120 AS
THE LAST ELEMENTS OF A WARM CORE TROPICAL CYCLONE ARE LOST.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH
TAU 72 WITH MINIMAL CROSS TRACK SPREADING. AS THE TIMING AND EXTENT
OF THE NORTHEASTWARD TURN VARIES AMONGST THE MEMBERS, THE CONSENSUS
BEYOND TAU 72 IS NOT AS TIGHT. FOR THIS REASON THE JTWC TRACK
FORECAST IS PLACED INITIALLY WITH HIGH CONFIDENCE AND WITH MEDIUM
CONFIDENCE THEREAFTER. RELIABLE MODEL INTENSITY GUIDANCE IS IN FAIR
AGREEMENT WITH ALL MEMBERS GENERALLY FOLLOWING THE MULTI-MODEL
CONSENSUS THROUGH THE FORECAST PERIOD. FOR THIS REASON THE JTWC
INTENSITY FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE.

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