Tropical Storm FRANCISCO Advisory 18.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (FRANCISCO) WARNING NR 09//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 26W (FRANCISCO), LOCATED APPROXIMATELY 152 NM WEST OF
ANDERSEN AFB, GUAM, HAS TRACKED NORTHWESTWARD AT 07 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
INDICATES AN INTENSE SYMMETRIC CORE OF DEEP CONVECTION AROUND A
DEFINED 15 NM EYE AND IMPROVED CONVECTIVE BANDING IN ALL QUADRANTS.
A 172251Z SSMIS MICROWAVE IMAGE REVEALS AN INTENSE SYSTEM WITH A
WELL DEFINED EYEWALL AND MULTIPLE CONVECTIVE FEEDER BANDS IN THE
OUTER PERIPHERIES. THE CURRENT POSITION IS BASED UPON THE WELL
DEFINED EYE IN THE MSI ANIMATION WITH HIGH CONFIDENCE. THE CURRENT
INTENSITY HAS BEEN INCREASED TO 120 KNOTS BASED ON THE RAPIDLY
IMPROVING STRUCTURE OF THE SYSTEM AND DVORAK INTENSITY ESTIMATES
FROM PGTW, KNES, AND RJTD THAT RANGE FROM 102 TO 127 KNOTS. UPPER
LEVEL ANALYSIS INDICATES A POINT SOURCE ANTICYCLONE REMAINS OVER THE
SYSTEM WHICH IS PROVIDING AMPLE RADIAL OUTFLOW AND LOW (05-10 KNOTS)
VERTICAL WIND SHEAR. TY FRANCISCO IS BEGINNING TO TRACK NORTHWEST
ALONG AN EXTENSION OF THE SUBTROPICAL RIDGE (STR) ALTHOUGH A SLIGHT
WOBBLE REMAINS IN THE OVERALL MOTION OF THE SYSEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING.
   B. THROUGH TAU 72, TY 26W IS EXPECTED TO SLOWLY TRACK
NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR LOCATED WELL
TO THE NORTH OF GUAM. FAVORABLE ENVIRONMENTAL CONDITIONS OF LOW
VERTICAL WIND SHEAR, WARM SEA SURFACE TEMPERATURES, AND AMPLE
OUTFLOW WILL ALLOW TY 26W TO INTENSIFY TO A MAXIMUM OF 135 KNOTS BY
TAU 36. AFTER TAU 48, AS THE SYSTEM GAINS LATITUDE, COOLING SEA
SURFACE WILL START A SLOW WEAKENING PROCESS. NUMERIC MODEL GUIDANCE
IS IN GOOD AGREEMENT THROUGH TAU 72, LEADING TO NOW HIGH CONFIDENCE
IN THIS PORTION OF THE FORECAST.
   C. AFTER TAU 72, TY 26W WILL BEGIN TO ROUND THE WESTERN EXTENT OF
THE STR, ALLOWING FOR A MORE NORTH-NORTHWESTWARD DIRECTION. FURTHER
DECREASING OCEAN PARAMETERS AND AN INCREASE IN VWS WILL CONTINUE THE
WEAKENING TREND THROUGH TAU 120. NUMERIC MODEL GUIDANCE CONTINUES TO
DIVERGE WIDELY AFTER TAU 72, DUE TO SOME DISAGREEMENT IN THE EXTENT
OF THE STR THAT IS EXPECTED TO BUILD ACROSS SOUTHERN JAPAN IN THE
EXTENDED TAUS. DUE TO THIS, THE FORECAST TRACK REMAINS CLOSE TO THE
MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE.//
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