WDPN33 PGTW 210300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (FRANCISCO) WARNING NR 21//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 26W (FRANCISCO), LOCATED APPROXIMATELY 613 NM SOUTHEAST 
OF KADENA AB, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE PAST 
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A 
RAGGED FILLED-EYE FEATURE THAT HAS PERSISTED WHILE THE DEEP 
CONVECTIVE FEEDER BANDS HAVE CONTINUED TO LOOSEN, RESULTING IN A 
SLIGHTLY LARGER OVERALL WIND FIELD. THE EYE FEATURE APPEARS FAIRLY 
ELONGATED AND LACKING SYMMETRY IN THE MSI. ADDITIONALLY, THERE IS A 
SLIGHT ELONGATION OCCURRING ALONG THE NORTHEAST PERIPHERY AS THE 
SYSTEM HAS NOW ESTABLISHED A POLEWARD OUTFLOW CHANNEL WITH THE MID-
LATITUDE WESTERLIES. A 210019Z AMSU-B MICROWAVE IMAGE REVEALS A WELL 
DEFINED MICROWAVE EYE FEATURE. THE INITIAL POSITION IS BASED ON THE 
MSI ANIMATION AS WELL AS THE AMSU-B IMAGE WITH HIGH CONFIDENCE. THE 
INITIAL INTENSITY OF 105 KNOTS IS BASED ON CONGRUENT DVORAK CURRENT 
INTENSITY ESTIMATES FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS 
INDICATES THE SYSTEM IS WITHIN 05 DEGREES SOUTH OF THE RIDGE AXIS 
AND IN AN AREA OF WEAK (5-10 KNOT) VERTICAL WIND SHEAR (VWS). THE 
POLEWARD OUTFLOW CHANNEL OBSERVED IN THE MSI IS ALSO APPARENT ON 
ANIMATED WATER VAPOR IMAGERY. 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, BUT THE FORECAST TRACK HAS CONTINUED TO MOVE 
SLIGHTLY MORE WESTWARD SPECIFICALLY AROUND THE RECURVE POINT IN THE 
FORECAST TRACK.
   B. THROUGH TAU 12, TY 26W IS EXPECTED TO CONTINUE ALONG ITS 
CURRENT TRACK UNDER THE STEERING INFLUENCE OF THE STR. AFTERWARDS, 
AN EXTENSION OF THE STR IS EXPECTED TO BUILD WESTWARD AND PUSH THE 
TRACK SLIGHTLY FURTHER WEST AS TY 26W BEGINS TO ROUND THE STR AXIS. 
THE SYSTEM HAS BEGUN TO SLOWLY WEAKEN DUE TO COOLING SEA SURFACE 
TEMPERATURES (SSTS). INCREASING VWS ASSOCIATED WITH THE MID- 
LATITUDE WESTERLIES WILL ALSO AID IN THE WEAKENING TREND. HOWEVER, 
THE INCREASED POLEWARD OUTFLOW WILL PARTIALLY OFFSET THE VWS AND 
HELP SUSTAIN THE CONVECTION, THEREBY TEMPERING THE WEAKENING TREND.
   C. AFTER TAU 72, TY FRANCISCO WILL CREST THE STR AXIS, ALLOWING 
FOR A MORE POLEWARD TRACK AND SETTING INTO A NORTHEASTWARD 
RECURVATURE OVER EASTERN JAPAN. COOLING SSTS AND FURTHER INCREASING 
VWS WILL AMPLIFY THE WEAKENING TREND. BY TAU 96 THE SYSTEM WILL 
BEGIN EXTRA-TROPICAL TRANSITION (ETT). THE SYSTEM IS FORECAST TO 
BRIEFLY TRACK OVER EASTERN JAPAN AND THEN REEMERGE OVER THE PACIFIC 
OCEAN AND COMPLETE ETT BY TAU 120. NUMERIC MODEL GUIDANCE HAS 
IMPROVED, BUT REMAINS WIDELY SPREAD AT TAU 72 AND BEYOND DUE TO 
VARYING SOLUTIONS TO THE ORIENTATION AND STRENGTH OF THE STR. 
OBJECTIVE AIDS, WITH THE EXCEPTION OF JGSM AND THE JAPANESE 
ENSEMBLE, HAVE CONSOLIDATED WITHIN A REASONABLE SPREAD AND ONLY 
SLIGHTLY VARY IN THE TIGHTNESS OF THE TURN AND TRACK SPEED AROUND 
THE RECURVE POINT. JGSM AND THE JAPANESE ENSEMBLE ARE WESTWARD 
OUTLIERS AND INDICATE TRACKS MUCH CLOSER TO OKINAWA. THE CURRENT 
FORECAST REMAINS CLOSE TO THE MULTI-MODEL CONSENSUS AND IS BIASED 
TOWARDS THE ECMWF SOLUTION. THOUGH MODEL GUIDANCE HAS IMPROVED, DUE 
TO THE CONTINUED UNCERTAINTY IN THE STEERING MECHANISM AT THE 
EXTENDED TAUS, THE CONFIDENCE IN THE FORECAST REMAINS LOW.//
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