320 FXUS63 KILX 192329 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 529 PM CST SAT JAN 19 2013 .DISCUSSION... ISSUED 247 PM CST SAT JAN 19 2013 LATEST SURFACE ANALYSIS HAD DEEPENING LOW PRESSURE CENTERED OVER THE WESTERN UPPER PENINSULA OF MICHIGAN...WITH A STRONG COLD FRONT EXTENDING SOUTHWEST INTO THE CENTRAL PLAINS. THE PASSAGE OF THIS FRONT LATER TONIGHT WILL USHER IN THE COLDEST AIR OF THE WINTER FOR THE FIRST HALF OF THE COMING WEEK. MAIN FORECAST CONCERNS TODAY REVOLVE AROUND HOW STRONG WINDS WILL BE UNTIL SUNDAY ON EITHER SIDE OF THE APPROACHING FRONT...PRECIPITATION CHANCES SUNDAY AND TUESDAY WITH TWO WEAK UPPER LEVEL DISTURBANCES...AND PRECIPITATION CHANCES/TYPES WITH A STRONGER SYSTEM THURSDAY/THURSDAY NIGHT. 12Z MODELS CONTINUE TO BE IN GOOD OVERALL AGREEMENT UNTIL THE THURSDAY/THURSDAY NIGHT SYSTEM. MODEL AGREEMENT AND RUN-TO-RUN CONSISTENCY WITH THE LATE WEEK SYSTEM IS FAIR AT BEST. HOWEVER...THERE HAS BEEN A DEFINITE SOUTHERLY TREND IN THIS STORM/S TRACK BY THE MODEL CONSENSUS. OBVIOUSLY...IF THIS TREND PERSISTS...IT WILL BE A COLDER AND POSSIBLY SNOWIER RESULT. IN ANY EVENT...FOLLOWING A MODEL BLEND IN THE WELL AGREED UPON SHORT TERM AND TO HELP FILTER OUT SOME OF THE DISAGREEMENT/NOISE IN THE EXTENDED RANGE OF THE FORECAST. SHORT TERM...TONIGHT THROUGH TUESDAY...AS EXPECTED...GUSTY SOUTHERLY WINDS AHEAD OF THE APPROACHING FRONT HAVE STAYED BELOW ADVISORY CRITERIA. WHILE WINDS ARE AROUND 40KTS WITHIN 3-4K FEET OF THE SURFACE...STRONG WAA ALOFT HAS LIMITED MIXING TO ABOUT 925 MB AND PRECLUDED THESE STRONGER WINDS FROM REACHING THE GROUND. AS THE COLD FRONT CLEARS THE AREA LATER TONIGHT...EXPECT WIND SPEEDS/GUSTS TO INCREASE FROM THEIR CURRENT LEVELS FOR A TIME AS THEY SHIFT NORTHWEST. STRONG CAA WILL DEEPEN MIXING HEIGHTS ALLOWING SOME OF THE STRONGER WINDS ALOFT TO BE TRANSPORTED TO THE SURFACE FOR A TIME. WHILE A COUPLE HOURS OF ADVISORY LEVEL WINDS CAN NOT BE RULED OUT FOR A TIME...ESPECIALLY ACROSS THE NORTH... FEEL CONDITIONS ARE TOO MARGINAL TO GO WITH A WIND ADVISORY. NEVERTHELESS...IT WILL STILL BE QUITE WINDY AT TIMES. COLD AIR WILL CONTINUE TO SURGE INTO THE AREA OVER THE NEXT FEW DAYS ON PERSISTENT NORTHWEST FLOW. HIGH TEMPERATURES IN THE TEENS AND LOWS IN THE SINGLE DIGITS WILL BE COMMON BY MONDAY AND ESPECIALLY TUESDAY. A COUPLE WEAKENING/SHEARING UPPER WAVES IN DEEP NORTHWESTERLY FLOW WILL IMPACT THE AREA BEHIND THE FRONT...THE FIRST SUNDAY AFTERNOON/NIGHT AND THE SECOND ON TUESDAY. STILL FEEL THESE FEATURES WILL BE TOO WEAK/MOISTURE STARVED TO PRODUCE MEASURABLE SNOWFALL. HOWEVER...FORECAST SOUNDINGS SUGGEST ENOUGH MOISTURE TO PRODUCE FLURRIES AS THE DISTURBANCES MOVE THROUGH. LONG TERM...WEDNESDAY THROUGH SATURDAY...THE ARCTIC AIR WILL LOSE ITS GRIP ON THE AREA FOR A TIME WEDNESDAY/THURSDAY AS THE UPPER LEVEL FLOW DEAMPLIFIES. THEN...A STRONG WAVE COMING IN OFF THE PACIFIC COAST WILL PUSH AN AREA OF LOW PRESSURE/FRONTAL SYSTEM THROUGH OUR VICINITY FOR THURSDAY/THURSDAY NIGHT. THIS SYSTEM IS LIKELY TO PRODUCE MEASURABLE PRECIPITATION LOCALLY...BUT THE PRECIPITATION TYPE IS STILL QUITE UP IN THE AIR. WHILE IT PREVIOUSLY LOOKED LIKE IT WOULD BE WARM ENOUGH ON THURSDAY FOR RAIN...THE SOUTHERLY TREND IN THE MODELS IS STARTING TO POINT TOWARD SNOW BEING MORE LIKELY. HOWEVER...THE GFS IS EVEN THREATENING FREEZING RAIN IN MUCH OF THE FORECAST AREA FOR THURSDAY AS IT BRINGS IN A SLUG OF WARM AIR ALOFT AND HOLDS ONTO SUB FREEZING SURFACE TEMPERATURES. GIVEN THE MODEL DISAGREEMENT AND RUN-TO-RUN INCONSISTENCY...HAVE BROAD BRUSHED A CHANCE OF RAIN/SNOW FOR THURSDAY...WITH SNOW CHANCES EVERYWHERE THURSDAY NIGHT. THE FORECAST FOR THIS PERIOD WILL UNDOUBTEDLY NEED TO BE TWEAKED AS THE ULTIMATE OUTCOME BECOMES MORE CLEAR. COLDER TEMPERATURES RETURN BEHIND THE THURSDAY SYSTEM AS THE UPPER LEVEL FLOW AMPLIFIES AGAIN. MAY SEE SOME LIGHT SNOW/FLURRIES INTO FRIDAY IN THE WRAP AROUND BEHIND THE DEPARTING STORM. BAK && .AVIATION... ISSUED 529 PM CST SAT JAN 19 2013 VFR CONDITIONS WILL CONTINUE AT ALL SITES NEXT 24HRS. CLEAR SKIES WILL GIVE WAY TO CLOUD COVER THIS EVENING AT PIA/BMI AS SCATTERED CLOUDS AROUND 3.5KFT ADVECT INTO THE REGION FROM THE NORTHWEST. SPI/DEC/CMI WILL BE CLEAR OVERNIGHT. DURING THE MORNING HOURS...ALL SITES WILL SEE BROKEN CLOUDS AT AROUND 10-12KFT ADVECT INTO THE REGION FROM THE WEST...BUT CLOUDS WILL LOWER DURING THE AFTERNOON HOURS. EXPECTING CIGS AROUND 3.5KFT AT PIA/BMI AND AROUND 5KFT AT SPI/DEC/CMI. WINDS WILL BE LIGHTER TO START THIS EVENING AS THE FRONT MOVES THROUGH...BUT THEN INCREASE AND BECOME A GUSTY AGAIN BEHIND THE FRONT THIS EVENING. THIS WILL CONTINUE OVERNIGHT AND THEN DECREASE IN THE MORNING. LIGHTER WINDS ARE EXPECTED TOMORROW MORNING AND AFTERNOON. WIND DIRECTION WILL BECOME NORTHWEST ONCE THE FRONT MOVES THROUGH AND THEN REMAIN THAT WAY THROUGH END OF FORECAST PERIOD. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$