005 FXUS63 KFSD 120334 AFDFSD AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 933 PM CST WED JAN 11 2012 .DISCUSSION... HAVE MADE MINOR UPDATE TO FORECAST TO LOWER LOW TEMPERATURES TONIGHT AND ADD MENTION OF FLURRIES TONIGHT INTO TOMORROW. STRONG NORTHWEST FLOW CONTINUES TO DOMINATE ACROSS THE REGION...THOUGH HAS DECREASED SOME FROM WHAT IT WAS EARLIER TODAY. THE STRONG WINDS HAVE AIDED IN BRINGING COOLER AIR INTO THE REGION. TEMPERATURES ARE FALLING OFF FASTER THAN EXPECTED...AND WITH RELATIVELY DRY AIRMASS NEAR THE SURFACE...TEMPERATURES SHOULD FALL IN THE SINGLE DIGITS IN MOST LOCATIONS EVEN WITH THE ATMOSPHERE SOMEWHAT MIXED. COOLEST LOCATIONS SHOULD BE ACROSS CENTRAL PORTIONS OF SOUTH DAKOTA WHERE THE SNOW IS SLIGHTLY DEEPER AND THE 925 HPA TEMPS COOL THE MOST. HAVE ADDED MENTION OF FLURRIES THROUGH THE OVERNIGHT PERIOD INTO TOMORROW WITH THE CLOUD LAYER EMBEDDED WITHIN A DEEP DENDRITIC LAYER NEAR THE SURFACE. MODELS ALSO SHOWING A WEAK AMOUNT OF LIFT AT THE TOP OF THE CLOUD LAYER....THOUGH LIMITED AMOUNTS OF MOISTURE SHOULD KEEP ACCUMULATIONS TO A TRACE OR LESS. && .PREV DISCUSSION.../ISSUED AT 245 PM CST/ SNOW BAND ASSOCIATED WITH THE MIDLEVEL FRONT SHOULD SINK SOUTH OF THE AREA THIS AFTERNOON...WITH OCCASIONAL FLURRIES REMAINING BEHIND WHERE SOME INSTABILITY WILL STILL BE PRESENT. WIND GUSTS ACROSS THE NORTHWESTERN HALF OF THE CWA SHOWING SIGNS OF DECREASING AS THE STRONGEST ADVECTION SUBSIDES...EVIDENCED BY THE LEVELING OFF OF TEMPERATURES IN THESE AREAS...AND THIS TREND SHOULD CONTINUE ACROSS THE REGION BY SUNSET...THEREFORE ALLOWING THE WIND ADVISORY TO EXPIRE. FLURRIES SHOULD TAPER OFF BY LATE AFTERNOON...HOWEVER SOME VERY LIGHT SNOW MAY DEVELOP AS A SUBTLE WAVE TRAVELS DOWN ON THE BACK SIDE OF THE LOW AFTER MIDNIGHT. RIGHT NOW...LOOKS LIKE MOISTURE WILL BE TOO SHALLOW FOR ANY ACCUMULATING SNOW...SO LEFT THE CHANCE OF PRECIPITATION VERY LOW AND STUCK WITH FLURRIES ACROSS THE EASTERN TWO THIRDS OF THE AREA. TEMPERATURES SHOULD NOT FALL TOO DRAMATICALLY TONIGHT DUE TO LOW LEVEL CLOUD COVER AND WINDS REMAINING IN THE 15 TO 20 KT RANGE...RESULTING IN A VERY GRADUAL FALL THROUGH SUNRISE. /LAFLIN CLOUDS AND FLURRIES ARE EXPECTED TO DECREASE FROM THE WEST THURSDAY AS COLD TROUGH IS FORCED EAST BY RIDGING FROM THE NORTHWEST. WINDY CONDITIONS WILL CONTINUE THROUGH THURSDAY BUT WINDS SHOULD STAY BELOW WIND ADVISORY LEVELS. TEMPERATURES WILL BE COLD WITH HIGHS GENERALLY IN THE 10 TO 20 RANGE...WHILE WIND CHILLS WILL BE BELOW ZERO BUT NOT DOWN TO WIND CHILL ADVISORY LEVELS. A WEAK SHORT WAVE HELPING TO FORCE THE ABOVE MENTIONED RIDGING WILL SPEED DOWN OVER AREA THURSDAY NIGHT. AN ASSORTMENT OF MIDDLE AND HIGH CLOUDS IS EXPECTED BUT NO SNOW. WINDS WILL DECREASE STEADILY AND IT WILL BE COLD...THOUGH THE CLOUDS ARE LIKELY TO HELP PREVENT TEMPERATURES FROM DROPPING TO ZERO OR BELOW. ANOTHER WAVE WILL FOLLOW FRIDAY NIGHT...STRONGER AND FURTHER NORTHEAST. AHEAD OF THIS WAVE FRIDAY SHOULD SEE SOME DECREASE THEN INCREASE IN CLOUDS BUT PARTLY CLOUDY OVERALL...AND A LITTLE WARMING. THE FRIDAY NIGHT INCREASE IN CLOUDS MAY LINGER INTO SATURDAY NORTHEAST AS SOME LOWER CLOUDS ARE LIKELY TO SWEEP ACROSS THAT AREA. AGAIN NO PRECIPITATION EXPECTED AT THIS TIME. CONTINUED WARMING AND SOME MIXING SHOULD PUSH TEMPERATURES UP INTO THE 30S. STRONG RIDGING AND WARMING WILL TAKE PLACE BEHIND THE ABOVE MENTIONED WAVE WITH 30S AND 40S EXPECTED SUNDAY. NEXT COLD FRONT CURRENTLY TIMED TO ARRIVE MONDAY AND THE TIMING WILL MAKE A DIFFERENCE OF COURSE ON MONDAY HIGH TEMPERATURES. CURRENT MODEL TREND IS FOR EARLY ENOUGH ARRIVAL TO DO SOME COOLING FOR MONDAY HIGH TEMPERATURES. TUESDAY WILL BE A RELATIVELY COLD DAY BEFORE RIDGING AND WARMING WEDNESDAY A A FREQUENT WARMING/COOLING CYCLE APPEARS TO BECOMING ESTABLISHED. NOTHING LOOKS STRONG ENOUGH OR DEEP ENOUGH TO BRING ENOUGH MOISTURE TO MENTION ANY REASONABLE CHANCE OF PRECIPITATION. A SLIGHT MODIFICATION TO OUR BALMY JANUARY PATTERN BUT SEEMINGLY NO CHANGE TO THE DRY PART. / WILLIAMS && .AVIATION.../FOR THE 00Z TAF ISSUANCE/ THE MAIN CONCERNS THIS TAF PERIOD ARE MVFR CIGS...WINDS...AND MINOR VSBY REDUCTIONS IN THE WAKE OF A MID LEVEL FRONT. WHILE THE MAJORITY OF THE SNOW HAS TAPERED TO FLURRIES AT THIS POINT...ANOTHER ROUND OF 3SM-6SM VSBYS AND LIGHT SNOW WILL BE POSSIBLE BETWEEN 08Z AND 15Z AS THE LAST WEAK IMPULSE ALONG THE WESTERN PERIPHERY OF THE DEPARTING TROUGH PASSES OVER. AFTER A BRIEF RESPITE TO LOW- END VFR CIGS THIS EVENING...A PERIOD OF MVFR CIGS IS ALSO EXPECTED TO ACCOMPANY THE WEAK WAVE OVERNIGHT. BRISK WINDS WILL PREVAIL THROUGH MID DAY THURSDAY...AND GENERALLY HOVER IN THE 20 TO 30 KT RANGE. WITH THE EXCEPTION OF KSUX /WHERE WINDS WILL REMAIN BRISK THROUGH THE PERIOD/...GUSTS WILL DIMINISH ON THURSDAY AFTERNOON AS SKIES ALSO BECOME MOSTLY CLEAR. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$