Tropical Storm FRANCISCO Advisory dim, 20.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (FRANCISCO) WARNING
NR 17//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON 26W (FRANCISCO), LOCATED APPROXIMATELY 762 NM
SOUTHEAST OF KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS THE SYSTEM HAS MAINTAINED A SYMMETRICAL 13-NM
EYE SURROUNDED BY A WELL DEFINED DEEP CONVECTIVE EYEWALL. THE MSI
ALSO DEPICTS A STRONG FEEDER BAND TIGHTLY WRAPPING AROUND THE
WESTERN SEMI-CIRCLE OF THE SYSTEM AS WELL AS A WEAKER BAND LOOSELY
WRAPPING AROUND THE EASTERN PERIPHERY. A 192226Z SSMIS MICROWAVE
IMAGE INDICATES THE DEEP CONVECTION WITHIN THE EYEWALL HAS SLIGHTLY
DEGRADED IN VARIOUS LOCATIONS, AND COULD BE THE RESULT OF AN EYEWALL
REPLACEMENT CYCLE (ERC). THE INITIAL POSITION IS BASED ON THE MSI
ANIMATION AND THE AFOREMENTIONED MICROWAVE IMAGE WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 140 KNOTS IS BASED ON CONGRUENT
DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW, RJTD, AND KNES. UPPER-
LEVEL ANALYSIS INDICATES A POINT SOURCE ANTICYCLONE REMAINS SLIGHTLY
DISPLACED OVER THE SYSTEM, PROVIDING HIGHLY-EFFICIENT RADIAL OUTFLOW
AND LOW (05-10 KNOT) VERTICAL WIND SHEAR (VWS). THE CYCLONE IS
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING.
   B. THROUGH TAU 48, STY 26W IS EXPECTED TO CONTINUE ALONG ITS
CURRENT TRACK UNDER THE STEERING INFLUENCE OF THE STR. BY TAU 72, AN
EXTENSION TO THE STR IS EXPECTED TO BUILD IN AND PUSH THE TRACK OF
THE SYSTEM SLIGHTLY FURTHER WEST AS STY 26W BEGINS TO ROUND THE STR
AXIS. THOUGH FAVORABLE UPPER LEVEL CONDITIONS CONTINUE TO EXIST,
THEY ARE CURRENTLY BEING OFFSET BY ERCS AND A TONGUE OF COOL SEA
SURFACE TEMPERATURES (SSTS). FRANCISCO APPEARS TO HAVE REACHED ITS
PEAK INTENSITY AND IS FORECAST TO SUSTAIN 140 KNOTS OVER THE NEXT 12
HOURS. AFTER TAU 12, THE SYSTEM WILL SUCCOMB TO INCREASING VWS AS IT
APPROACHES THE MID-LATITUDE WESTERLIES, AS WELL AS EVEN COLDER SSTS
WHICH WILL FURTHER ERODE THE LOW LEVEL INFLOW. HOWEVER, INCREASED
POLEWARD OUTFLOW COULD POTENTIALLY OFFSET THE VWS AND HELP SUSTAIN
THE CONVECTION, THEREBY TEMPERING THE WEAKENING TREND.
   C. AFTER TAU 72, STY FRANCISCO WILL BEGIN TO CREST THE STR AXIS,
ALLOWING FOR A MORE POLEWARD TRACK AND SETTING INTO A NORTHEASTWARD
RECURVATURE TOWARD JAPAN. A DECREASE IN SSTS AND FURTHER INCREASE IN
VWS WILL AMPLIFY THE WEAKENING TREND THROUGH TAU 120 AS THE SYSTEM
BEGINS EXTRA-TROPICAL TRANSITION. NUMERIC MODEL GUIDANCE REMAINS
WIDELY SPREAD IN THE EXTENDED TAUS DUE TO VARYING SOLUTIONS TO THE
ORIENTATION AND STRENGTH OF THE STR. ALL OBJECTIVE AIDS INDICATE
SOME DEGREE OF A RECURVE SCENARIO, BUT WIDELY VARY IN THE TIGHTNESS
OF THE TURN AS WELL AS TRACK SPEED. THE CURRENT FORECAST REMAINS
CLOSE TO THE MULTI-MODEL CONSENSUS AND IS BIAS TOWARDS THE ECMWF
SOLUTION. DUE TO THE HIGH UNCERTAINTY IN THE STEERING MECHANISM AT
THE EXTENDED TAUS, THE CONFIDENCE IN THE FORECAST REMAINS LOW.//
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