672 FXUS63 KILX 152342 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 542 PM CST TUE JAN 15 2013 .DISCUSSION... ISSUED 233 PM CST TUE JAN 15 2013 MAIN WEATHER STORY IS THE APPROACHING ARCTIC AIRMASS EXPECTED EARLY NEXT WEEK. AFTER A BRIEF RETURN TO ABOVE NORMAL TEMPERATURES OVER THE NEXT COUPLE OF DAYS...MUCH BELOW NORMAL READINGS WILL SPILL INTO THE MIDWEST SUNDAY THROUGH TUESDAY. 19Z/1PM SURFACE ANALYSIS SHOWS HIGH PRESSURE EXTENDING FROM MICHIGAN INTO MISSOURI...WHICH IS PROVIDING COLD AND DRY WEATHER TO CENTRAL ILLINOIS. FURTHER SOUTH...PERSISTENT FRONTAL BOUNDARY REMAINS DRAPED ALONG THE GULF COAST. WEAK WAVE OF LOW PRESSURE RIDING NORTHWARD ALONG THE BOUNDARY IS SPREADING CLOUDS/WINTRY PRECIP ACROSS THE OZARKS INTO THE LOWER OHIO RIVER VALLEY. SHORT TERM...TONIGHT THROUGH FRIDAY A MIXTURE OF SNOW AND SLEET WILL CONTINUE TO SPREAD NORTHEASTWARD ACROSS SOUTHERN MISSOURI AND WESTERN KENTUCKY THIS EVENING...IN ADVANCE OF A WEAK SHORT-WAVE TROUGH. BASED ON LATEST SATELLITE/RADAR LOOPS...AS WELL AS 12Z NAM/GFS GUIDANCE...IT APPEARS THIS PRECIP WILL STAY ENTIRELY SOUTHEAST OF THE KILX CWA TONIGHT. SKIES WILL REMAIN PARTLY TO MOSTLY CLOUDY DURING THE EVENING...THEN CLEARING WILL TAKE PLACE FROM WEST TO EAST OVERNIGHT. THANKS TO THE INCREASED CLOUD COVER...LOW TEMPERATURES WILL NOT BE QUITE AS COLD AS THEY HAVE BEEN IN RECENT NIGHTS...WITH MOST LOCATIONS DIPPING INTO THE TEENS. COLDEST READINGS OF AROUND 10 DEGREES WILL BE FOUND ACROSS THE FAR NW CWA AROUND GALESBURG...WHERE A LIGHT SNOW COVER IS IN PLACE AND SKIES WILL CLEAR EARLIEST. AS HIGH PRESSURE SHIFTS OFF TO THE EAST...A WARM/SOUTHERLY RETURN FLOW WILL DEVELOP ON WEDNESDAY. AMPLE SUNSHINE WILL HELP BOOST TEMPERATURES INTO THE UPPER 30S AND LOWER 40S. NORTHWESTERLY FLOW ACROSS THE NORTHERN TIER OF STATES INTO THE GREAT LAKES WILL PUSH A WEAK COLD FRONT THROUGH ILLINOIS WEDNESDAY NIGHT. FORECAST SOUNDINGS ARE QUITE DRY AHEAD OF THIS BOUNDARY...SUGGESTING LITTLE MORE THAN A FEW CLOUDS WITH FROPA. TEMPS WILL ONLY DROP A FEW DEGREES FOR THURSDAY...GENERALLY REACHING THE LOWER TO MIDDLE 30S. COOL-DOWN WILL BE SHORT-LIVED HOWEVER...AS SOUTHERLY FLOW WILL RETURN BY FRIDAY. TIGHTENING PRESSURE GRADIENT BETWEEN DEPARTING HIGH AND NEXT APPROACHING SYSTEM WILL SUPPORT SOUTHWESTERLY WINDS GUSTING TO BETWEEN 20 AND 25 MPH. THIS STRONG FLOW COMBINED WITH FULL SUNSHINE WILL HELP BOOST HIGHS WELL INTO THE 40S. LONG TERM...SATURDAY THROUGH TUESDAY 12Z JAN 15 MODELS CONTINUE TO ADVERTISE A SIGNIFICANT PATTERN CHANGE EARLY NEXT WEEK...FEATURING A MAJOR CHUNK OF ARCTIC AIR SURGING SOUTHWARD INTO THE EASTERN CONUS. CURRENT ANALYSIS SHOWS CORE OF COLD AIRMASS IN PLACE W/NW OF HUDSON BAY...WHERE 850MB TEMPS ARE IN THE -30 TO -35C RANGE AND SURFACE TEMPS WERE AS COLD AS -45F THIS MORNING. WHILE THIS PARTICULAR AIRMASS WILL REMAIN TO THE NORTH ACROSS CANADA OVER THE NEXT SEVERAL DAYS...A PORTION WILL PLUNGE SOUTHWARD INTO THE NORTHERN PLAINS ON SATURDAY...THEN FURTHER SOUTH INTO THE MIDWEST ON SUNDAY. ARCTIC FRONT IS SLATED TO PASS THROUGH CENTRAL ILLINOIS SATURDAY NIGHT...HOWEVER LACK OF AVAILABLE MOISTURE WILL MEAN A CONTINUED DRY FORECAST. TEMPS WILL RESPOND ABRUPTLY...DROPPING FROM THE 40S ON SATURDAY INTO THE 20S BY SUNDAY. A RE-ENFORCING SURGE OF BITTERLY COLD AIR WILL PUSH SOUTHWARD SUNDAY NIGHT INTO MONDAY...WITH BOTH THE GFS AND ECMWF INDICATING SOME LIGHT QPF ASSOCIATED WITH STRONG UPPER-LEVEL WAVE. GIVEN A CONTINUED LACK OF DEEP MOISTURE AND THE RELATIVELY FAST SPEED OF THE SYSTEM...WILL ONLY FEATURE SLIGHT CHANCE POPS FOR LIGHT SNOW WITH FROPA. 850MB TEMPS ARE PROGGED TO PLUNGE INTO THE -20 TO -25C RANGE BY MONDAY AND TUESDAY...SUPPORTING THE COLDEST WEATHER OF THE WINTER THUS FAR. HIGH TEMPS MON/TUE WILL STRUGGLE TO REACH THE TEENS...WHILE OVERNIGHT LOWS DROP INTO THE SINGLE DIGITS. COULD EVEN SEE A FEW READINGS BELOW ZERO MONDAY NIGHT ACROSS THE N/NW CWA...HOWEVER LACK OF SIGNIFICANT SNOW COVER WILL LIKELY KEEP TEMPS AOA ZERO DEGREES. BARNES && .AVIATION... ISSUED 542 PM CST TUE JAN 15 2013 VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES WITH HIGH CIRRUS CLOUDS AT PIA/BMI/SPI OVERNIGHT. DEC/CMI WILL SEE VFR AS WELL WITH MID CLOUDS FOR FIRST COUPLE OF HOURS AND THEN HIGH CIRRUS REMAINDER OF THE NIGHT. CLEAR SKIES ARE EXPECTED IN THE MORNING AS THE HIGH PRESSURE RIDGE MOVES EAST OF THE AREA AHEAD OF THE NEXT WEAK FRONT MOVES INTO THE AREA. ASSOCIATED WITH THE FRONT SHOULD BE SOME CLOUDS AROUND 3.5KFT MOVING INTO THE AREA...AFFECTING PIA/BMI/SPI BEFORE 00Z...DEC AND CMI WILL BE AFTER 00Z. WINDS WILL BE LIGHT AND VARIABLE OVERNIGHT AND THEN BECOME SOUTHWEST TOMORROW WITH INCREASING WIND SPEEDS TOMORROW AFTERNOON. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$