Tropical Storm LAN Advisory vie, 20-10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (LAN) WARNING NR 19//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 25W (LAN), LOCATED APPROXIMATELY 478 NM SOUTH-SOUTHEAST
OF KADENA AB, HAS TRACKED NORTHWARD AT 08 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED MULTI-SPECTRAL SATELLITE IMAGERY SHOWS
DEEP CONVECTIVE BANDING WRAPPING INTO A LARGE, CONSOLIDATING, LOW
LEVEL CIRCULATION CENTER (LLCC). THE SYSTEM HAS BEGUN TO
CONSOLIDATE, THOUGH IT REMAINS VERY BROAD, COVERING OVER 850 NM. A
192131Z 91 GHZ SSMIS IMAGE AND A 192206Z 37 GHZ WINDSAT DEPICT DEEP
CONVECTIVE BANDING WRAPPING INTO A WELL DEFINED MICROWAVE EYE
FEATURE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON EXTRAPOLATION OF THE MICROWAVE EYE FEATURE AND THE PGTW
SATELLITE FIX. THE INITIAL INTENSITY OF 85 KNOTS IS HEDGED ABOVE
DVORAK INTENSITY ASSESSMENTS OF T4.5 (77 KNOTS) FROM BOTH PGTW AND
RJTD AND IS SUPPORTED BY A SATCON ESTIMATE OF 83 KNOTS.
ENVIRONMENTAL ANALYSIS INDICATES THAT THE SYSTEM IS IN AN AREA OF
LOW (5-15 KNOT) VERTICAL WIND SHEAR (VWS) AND IS TRACKING THROUGH
AN AREA OF VERY WARM (30 TO 31 CELSIUS) SEA SURFACE TEMPERATURES.
TYPHOON LAN CURRENTLY HAS AN OUTFLOW CHANNEL THAT EXITS THE
POLEWARD SIDE OF THE STORM, WRAPS AROUND THE EASTERN PERIPHERY, AND
EXTENDS EQUATORWARD. TY 25W IS TRACKING NORTH-NORTHEAST ALONG THE
WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) LOCATED TO THE
NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 25W IS FORECAST TO TRACK NORTH-NORTHEASTWARD OVER THE NEXT
12-24 HOURS UNDER THE INFLUENCE OF THE STR. AFTER CROSSING THE
RIDGE AXIS AROUND TAU 24, THE SYSTEM WILL BEGIN TO ACCELERATE AND
RECURVE BACK TO THE NORTHEAST ON A TRACK THAT WILL PASS ALONG THE
EAST COAST OF JAPAN. FAVORABLE ENVIRONMENTAL CONDITIONS WILL
PERSIST AND POLEWARD OUTFLOW WILL BE ENHANCED AS THE SYSTEM
APPROACHES THE MID-LATITUDE WESTERLIES. THIS ENHANCED OUTFLOW
WILL ALLOW FOR A PERIOD OF RAPID INTENSIFICATION WITH THE SYSTEM
REACHING A PEAK INTENSITY OF 115 KNOTS AROUND TAU 36. AFTER TAU 36,
THE SYSTEM WILL BEGIN TO GRADUALLY WEAKEN AS IT BEGINS TO INTERACT
WITH A PASSING MID-LATITUDE TROUGH AND BECOMES EMBEDDED IN THE
MID-LATITUDE WESTERLIES, INCREASING VERTICAL WIND SHEAR. THE TROUGH
INTERACTION AND WESTERLIES WILL CAUSE TY 25W TO BEGIN EXTRA-
TROPICAL TRANSITION. DYNAMIC MODEL GUIDANCE IS IN STRONG AGREEMENT,
LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST.
   C. AFTER TAU 72, TY LAN WILL CONTINUE TO ACCELERATE
NORTHEASTWARD AS IT BECOMES FULLY EMBEDDED IN THE BAROCLINIC ZONE.
INCREASING VWS AND THE SYSTEM TRACKING THROUGH COOLER (<26 CELSIUS)
SEA SURFACE TEMPERATURES WILL WEAKEN THE SYSTEM FROM TAU 72 THROUGH
THE DURATION OF THE FORECAST PERIOD. SHORTLY AFTER TAU 72, THE
SYSTEM IS FORECAST TO MAKE A BRIEF LANDFALL BETWEEN KYOTO AND
TOKYO. THE SYSTEM?S NORTHEASTERLY TRACK WILL TAKE IT BACK OUT OVER
THE PACIFIC OCEAN SOUTH OF SENDAI. TY LAN WILL CONTINUE TO TRACK TO
THE NORTHEAST AND COMPLETE EXTRA-TROPICAL TRANSITION BY TAU 96,
BECOMING A HURRICANE-FORCE COLD CORE LOW WITH AN EXPANSIVE WIND
FIELD. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT FOR THE TRACK
DIRECTION, HOWEVER, VARIATIONS IN THE TRACK SPEED AFTER TAU 48 LEAD
TO A SIGNIFICANT SPREAD IN THE GUIDANCE BY TAU 96. DUE TO THE
UNCERTAINTY IN STORM SPEED IN THE LATER TAUS, THERE IS LOW
CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST.//
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