Issued by NWS Duluth, MN
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000 FXUS63 KDLH 251218 AFDDLH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 618 AM CST WED NOV 25 2009 .AVIATION...12Z TAFS. MVFR WITH AREAS OF VFR FROM KBRD TO KINL THROUGH 16-18Z TIME FRAME AS COLD AIR CHANGES PCPN OVER TO -SN. AFTER 18Z...KINL/KBRD EXPECTED TO BECOME VFR AS HIGH PRESSURE APPROACHES FROM THE WEST. KHIB/KDLH/KHYR CLOSER TO THE LEADING COLD FRONT SLOWLY EXITING MN INTO WI AT 12Z. MAINLY IFR CONDITIONS...OCCASIONALLY MVFR...NEAR THIS FRONT WITH PCPN TYPE BEING PRIMARILY -RA. HOWEVER...THE -RA WILL MIX WITH THEN CHANGE TO -SN THROUGH THE DAY AS COLDER AIR FILTERS IN FROM THE SFC HIGH ARRIVING. -DZ/BR ALSO EXPECTED AHEAD OF THE COLD FRONT THIS MORNING. LOOK FOR CONDITIONS TO IMPROVE TO VFR IN THE 03-06Z RANGE. && .PREV DISCUSSION... /ISSUED 406 AM CST WED NOV 25 2009/ DISCUSSION...LATEST SFC ANALYSIS SHOWS A COLD FRONT EXTENDING FROM THE ARROWHEAD OF MN SOUTH OVER WRN LAKE SUPERIOR AND NWRN WI. AN AREA OF RAIN HAS BECOME MORE ORGANIZED INVOF THE FRONT ACROSS OUR ERN ZONES EARLY THIS MORNING. FARTHER WEST...COLDER AIR HAS MOVED IN ACROSS OUR WESTERN ZONES WITH TEMPS CURRENTLY IN THE UPPER 20S AND LOWER 30S. AREAS OF FOG WILL LINGER ACROSS THE CWA THROUGH THIS MORNING DUE TO ABUNDANT LOW-LEVEL MOISTURE ASSOCIATED WITH THE FRONT. THE RAIN WILL GRADUALLY SPREAD ACROSS ALL OF NWRN WI TODAY...WHILE ENDING ACROSS THE ARROWHEAD REGION. WITH COLDER AIR ADVECTING IN FROM THE WEST AND NORTH...SOME OF THE PRECIP ACROSS OUR MN ZONES MAY MIX WITH OR CHANGE OVER TO LIGHT SNOW TODAY. BY TONIGHT...ANY PRECIP SHOULD BE IN THE FORM OF SNOW...EXCEPT ACROSS NWRN WI THIS EVENING WHERE A MIX OF RAIN AND SNOW IS EXPECTED. THE BEST CHANCE FOR PRECIPITATION WILL BE ACROSS THE SNOWBELT OF NWRN WI WHERE LAKE EFFECT/ENHANCEMENT AND OROGRAPHIC LIFT WILL AID IN THE DEVELOPMENT OF PRECIP. ELSEWHERE CONDITIONS WILL BE MOSTLY DRY AND COLD TONIGHT AND TOMORROW AS HIGH PRESSURE BUILDS IN OVER THE MIDWEST. THE LAKE EFFECT SNOW WILL TAPER OFF ON THURSDAY...AND SHOULD END BY EARLY THURSDAY EVENING. EXTENDED...THURSDAY NIGHT THROUGH TUESDAY. SFC RIDGING WILL COVER THE FA THURSDAY NIGHT THROUGH SATURDAY. EVEN THOUGH AN UPPER LEVEL SHORT WAVE WILL CROSS SOUTHERN CANADA NEAR THE MN BORDER...THE BULK OF THE LIFT WILL REMAIN N OF THE BORDER. SATURDAY NIGHT AND SUNDAY THE MODELS BEGIN TO DIVERGE IN THEIR SOLUTIONS AND HOW THE FA IS AFFECTED. 00Z/25 ECMWF AGREES WITH CANADIAN GLOBAL THAT PCPN WILL BE FOUND ACROSS THE NORTHERN HALF OF THE FA AND HAVE FOLLOWED ITS SOLUTIONS. REST OF THE FORECAST UNCHANGED. AVIATION.../06Z TAF ISSUANCE/ WIDE RANGE OF CONDITIONS EXPECTED THRU THE TAF PD. WHERE CLEARING LINE HAS MOVED IN FROM THE WEST...VSBYS HAVE DROPPED DOWN IN FG. EXPECT THIS TO LIFT BY DAYBREAK AS HIGHER CLDS AND DRIER AIR MOVE IN. ELSWHERE...IFR/MVFR CIGS HAVE BEEN MORE OR LESS STEADY STATE...BUT VSBYS ARE VARYING GREATLY AS THE FG COMES AND GOES. CONDITIONS SHUD GRADUALLY IMPROVE ON WED AS A LOW PRESS SYSTEM OVR IA MOVES TWRD NRN LWR MI. THIS WILL BRING PDS OF RA AND STRONGER NW WINDS WHICH WILL GENERALLY IMPROVE VSBY AND BRING CIGS UP TO MVFR. && .POINT TEMPS/POPS... DLH 38 24 34 20 / 40 20 10 10 INL 36 19 30 20 / 20 20 10 0 BRD 37 24 35 23 / 60 10 0 0 HYR 41 28 35 23 / 70 50 20 10 ASX 41 30 37 25 / 60 50 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ BERDES/GSF