WDPN31 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (LAN) WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.2N 143.9E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 143 NM EAST OF IWO TO
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY OVER THE PAST SIX HOURS
SHOWS A SUBSTANTIAL INCREASE IN ORGANIZATION AND CONSOLIDATION
WITHIN THE CORE OF TYPHOON 07W (LAN). DEEP CONVECTION HAS
COMPLETELY ENCIRCLED THE LOW-LEVEL CIRCULATION AND AN EYE HAS
DEVELOPED. THE SYSTEM IS ALSO SHOWING IMPROVED SYMMETRY. ANIMATED
WATER VAPOR IMAGERY SHOWS THE SYSTEM IS STILL BENEFITING FROM
IMPROVED OUTFLOW TO THE NORTHEAST, BUT IT IS MOVING AWAY FROM THE
EQUATORWARD OUTFLOW CHANNEL.  DRY AIR ENTRAINMENT IS DECREASING.
THE CURRENT INTENSITY ASSESSMENT IS BASED ON A JTWC DVORAK ASSESSMENT 
OF T4.0.  THE JMA ESTIMATE IS LOWER, BUT BOTH RCTP AND KNES ARE UP TO 
T4.5. CIMSS OBJECTIVE GUIDANCE SUCH AS ADT, AIDT, AND DPRINT ARE ALSO 
HIGHER AS THEY HAVE BEEN FOR SEVERAL CYCLES.  IT WAS TEMPTING FOR A 
MOMENT TO GO ABOVE THE JTWC DVORAK DUE TO THE IMPROVED LOOK IN 
SATELLITE ANIMATION, BUT A 092008Z SAR, A 092025Z SMAP PASS, AS WELL 
AS THE DMINT DATA CONFIRM THE VALIDITY OF THE JTWC DVORAK.  TY 07W IS 
TRACKING THROUGH A LOW SHEAR ENVIRONMENT WITH 30-31C SEA SURFACE 
TEMPERATURES AND THE WATER REMAINS WARM ALL THE WAY TO WITHIN 50 NM OF 
THE COAST OF HONSHU.  THE SYSTEM IS BEING STEERED POLEWARD BY THE 
SOUTHWESTERN FLANK OF THE SUBTROPICAL RIDGE, WHICH EXTENDS FROM A 
595DM 500MB HEIGHT CENTER NEAR 25N 170W ALL THE WAY ACROSS NORTHERN 
HONSHU.

INITIAL WIND RADII BASIS: SMAP DATA FROM 092008Z. 

CURRENT STEERING MECHANISM: THE WESTERN FLANK OF THE SUBTROPICAL
RIDGE.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 74 KTS AT 092330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   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 LAN WILL STEADILY INTENSIFY AT A
CLIMATOLOGICAL RATE ALONG ITS POLEWARD TRACK. THE DEEP LAYER
STEERING RIDGE TO THE WEST OF THE SYSTEM WILL PREVENT RECURVATURE
AND FORCE THE SYSTEM TO REMAIN ON A POLEWARD TRACK. THERE IS GOOD
CONFIDENCE THAT THE SYSTEM WILL MAKE LANDFALL WELL ABOVE TYPHOON
STRENGTH, BUT BELOW 100 KNOTS, AND IMPACT THE KANTO PLAIN AND
YOKOSUKA AREA. A BALANCE OF FAVORABLE AND UNFAVORABLE ENVIRONMENTAL
CONDITIONS WILL ALLOW TY 07W TO INTENSIFY AT A NEAR CLIMATOLOGICAL
RATE.  SUBSTANTIAL SUBSIDENCE AND DRY AIR NORTH OF THE 30TH
LATITUDE WILL CAP THE SYSTEM AT UNDER 100KTS AND PREVENT RAPID
INTENSIFICATION. 29-31C SEA WATER TEMPERATURES AND LOW VERTICAL WIND
SHEAR EXIST ALL THE WAY UP TO NEAR THE COAST.  THE KUROSHIO CURRENT
IS VERY NEAR THE COAST WITH ONLY A SHORT ZONE OF COOL WATERS PRIOR
TO LANDFALL, SO THE SYSTEM IS EXPECTED TO MAKE LANDFALL AT WELL
ABOVE TYPHOON STRENGTH. 

MODEL DISCUSSION: BOTH ALONG-TRACK AND CROSS-TRACK SPREAD HAVE
INCREASED OVER THE PAST TWO CYCLES, BUT THE GUIDANCE CONTINUES TO
POINT TO A LANDFALL BETWEEN THE WAKAYAMA AND CHIBA PENINSULAS.
TIMING IS A GREATER CONCERN DUE TO THE UNSTEADY ALONG TRACK SPREAD.
WITH EACH PASSING CYCLE THE GUIDANCE SHOULD FOCUS MORE TIGHTLY. 
THE JTWC TRACK FORECAST STAYS NEAR THE ENSEMBLE MEANS AND THE MULTI-
MODEL CONSENSUS.  THE INTENSITY FORECAST STAYS NEAR THE MEAN FOR
THE FIRST 36 HOURS, THAN RIDES ABOUT 10KTS HIGHER AS IT SPLITS THE 
MEAN BETWEEN THE HIGHER SKILLED HFAS AND HWRF MESOSCALE AND COUPLED 
MODELS. 

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