WDPN31 PGTW 261500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (NIDA) WARNING NR 
19//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. SUPER TYPHOON (STY) 26W (NIDA) HAS TRACKED NORTH-
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL 
STEERING RIDGE AT 07 KNOTS OVER THE PAST SIX HOURS. ALTHOUGH STY 
NIDA STILL HAS A WELL-DEFINED 20-NM EYE, ANIMATED INFRARED IMAGERY 
SHOWS CLOUD TOPS ASSOCIATED WITH THE DEEP CONVECTION HAVE WARMED 
WHILE THE OVERALL CONVECTIVE STRUCTURE HAS BECOME MORE ASYMMETRICAL 
AS THE GREATEST EXTENT OF DEEP CONVECTION HAS STARTED TO SHIFT TO 
THE EAST OF THE SYSTEM CENTER. ACCORDINGLY, THE SYSTEM HAS WEAKENED 
SLIGHTLY OVER THE PAST TWELVE HOURS AND THE CURRENT INTENSITY IS 
BASED ON A COMBINATION OF DVORAK ESTIMATES FROM PGTW (140 KNOTS), 
KNES (140 KNOTS) AND RJTD (155 KNOTS). ADDITIONALLY, A 261037Z TRMM 
MICROWAVE IMAGE REVEALS A CONCENTRIC OUTER EYEWALL HAS CHOKED OFF 
THE INFLOW TO THE INNER EYEWALL PREVIOUSLY EVIDENT IN A 260932Z 
SSMIS IMAGE, SIGNALING THAT STY NIDA IS IN THE MIDDLE OF AN EYEWALL 
REPLACEMENT CYCLE. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM 
CONTINUES TO HAVE AN ANTICYCLONE ALOFT, WHICH IS PROVIDING STRONG 
RADIAL OUTFLOW, AND WATER VAPOR IMAGERY SHOWS IMPROVED POLEWARD 
OUTFLOW INTO THE MID-LATITUDE WESTERLIES.
3. FORECAST REASONING.
    A. THE FORECAST REASONING HAS NOT CHANGED SIGNIFICANTLY SINCE 
THE LAST PROGNOSTIC REASONING BULLETIN.
    B. STY NIDA IS EXPECTED TO CONTINUE TRACKING SLOWLY NORTH-
NORTHWESTWARD TOWARDS THE SUBTROPICAL RIDGE AXIS OVER THE NEXT 36 TO 
48 HOURS. OVER THE NEXT TWO DAYS, NIDA IS ALSO FORECAST TO REMAIN A 
STRONG TYPHOON AS THE SYSTEM'S SECONDARY EYEWALL STARTS TO CONSTRICT 
AND ITS POLEWARD OUTFLOW IMPROVES. BY TAU 48, NIDA SHOULD CREST THE 
SUBTROPICAL RIDGE AXIS AND BEGIN ACCELERATING INTO THE MID-
LATITUDES. THE NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A 
RECURVATURE SCENARIO. HOWEVER, THE JGSM AND UKMO SOLUTIONS CONTINUE 
TO DEPICT A WESTWARD, STRAIGHT-RUNNING TYPE TRACK. THIS TRACK SEEMS 
VERY UNLIKELY GIVEN THE EASTWARD-MOVING MID-LATITUDE TROUGH, STRONG 
WESTERLY FLOW AROUND 25 DEGREES NORTH (AS INDICATED BY UPPER-AIR 
SOUNDINGS OUT OF CHICHIJIMA) AND THE TENDENCY FOR A LARGE SYSTEM TO 
TURN POLEWARD DUE TO THE BETA EFFECT. AS FOR THE RECURVATURE, THERE 
APPEARS TO BE BETTER CONSENSUS WITH A WESTERN-MOST POINT OF 138 
DEGREES EAST.
    C. IN THE EXTENDED TAUS, STY NIDA WILL ACCELERATE INTO THE MID-
LATITUDES AND RAPIDLY WEAKEN AS IT SUCCUMBS TO UNFAVORABLE VERTICAL 
WIND SHEAR AND COLDER SEA SURFACE TEMPERATURES. BY TAU 120, THE 
SYSTEM WILL START TO ENGAGE WITH THE BAROCLINIC ZONE AND BEGIN 
EXTRATROPICAL TRANSITION. THIS FORECAST IS FASTER THAN THE JTWC 
CONSENSUS AT DAYS FOUR AND FIVE DUE TO THE CONSENSUS BEING SKEWED BY 
THE UKMO SOLUTION.//
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