000 FXUS65 KBYZ 051614 AFDBYZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BILLINGS MT 914 AM MST THU DEC 5 2013 .UPDATE... FORECAST REMAINS IN GOOD SHAPE SO NO UPDATES PLANNED AT THIS TIME. LOCAL AREAS OF DENSE AND FREEZING FOG THAT WERE IN THE BILLINGS VICINITY HAVE DISSIPATED DURING THE PAST HOUR. MOSTLY SUNNY SKIES ALONG WITH BITTERLY COLD TEMPERATURES WILL PREVAIL THROUGHOUT THE DAY. WEST WINDS 10 TO 15 MPH PRODUCING WIND CHILLS OF -20 TO -40 DEGREES WILL CONTINUE TODAY FROM ROSEBUD COUNTY EASTWARD. CANT RULE OUT A FEW LOCALIZED AREAS IN OTHER PORTIONS OF THE FORECAST AREA SEEING WIND CHILL VALUES IN THIS RANGE ESPECIALLY IN WESTERN RIVER VALLEYS WHERE DRAINAGE WINDS WILL TREND OVER 10 MPH AT TIMES. HOWEVER...DO NOT FEEL STRONGER WINDS WILL BE WIDESPREAD ENOUGH TO EXPAND WIND CHILL ADVISORY FURTHER WEST AT THIS TIME. HOOLEY && .SHORT TERM...VALID FOR TDY AND FRI... COLD ARCTIC AIR WILL REMAIN ENTRENCHED ACROSS THE AREA THROUGH THE WEEKEND. DAYTIME TEMPERATURES WILL RISE TO NEAR ZERO WITH TEENS TO 20S BELOW FOR OVERNIGHT LOWS. NORTHWESTERLY WINDS OF 10 TO 20 MPH WILL CONTINUE OVER EASTERN AREAS TODAY. WIDESPREAD WIND CHILL VALUES OF 20 TO 35 BELOW ZERO WILL PERSIST FOR AREAS EAST OF ROSEBUD COUNTY AND THUS NO CHANGES TO THE GOING WIND CHILL ADVISORY FOR THIS AREA. CANT RULE OUT A FEW LOCALIZED AREAS IN OTHER PORTIONS OF THE FORECAST AREA SEEING WIND CHILL VALUES IN THIS RANGE ESPECIALLY IN WESTERN RIVER VALLEYS WHERE DRAINAGE WINDS WILL TREND OVER 10 MPH AT TIMES...BUT DONT FEEL STRONGER WINDS WILL BE WIDESPREAD ENOUGH TO EXPAND WIND CHILL ADVISORY FURTHER WEST AT THIS TIME. A REINFORCING SHOT OF COLD AIR DROPS INTO THE AREA LATE TONIGHT WHICH WILL TURN WINDS NORTHERLY THEN EASTERLY OVER CENTRAL AND WESTERN ZONES. EASTERLY UPSLOPE WINDS WILL GENERATE ENOUGH LIFT FOR SOME VERY LIGHT SNOW OR FLURRIES TONIGHT...TURNING TO A BETTER CHANCE OF ACCUMULATING SNOW FRIDAY AND FRIDAY NIGHT AS WEAK UPPER LEVEL ENERGY MOVES THROUGH. HOWEVER THERE IS LITTLE IN THE WAY OF MOISTURE ADVECTION WITH THIS SYSTEM AND GIVEN THE COLD TEMPERATURES WOULDNT EXPECT ACCUMULATIONS TO BE MORE THAN HALF AN INCH TO AN INCH AT THE MOST. THE EASTERLY WINDS ARE FORECAST TO BE ABOVE 10 MPH IN MOST AREAS LATE TONIGHT THROUGH FRIDAY WHICH MAY NECESSITATE FURTHER WIND CHILL ADVISORIES FOR CENTRAL AND WESTERN LOWER ELEVATIONS INCLUDING BILLINGS. WHILE TEMPERATURES WILL BE VERY COLD...WE MAY NOT SEE MANY RECORDS FALL THIS WEEK AS THE SAME PERIOD IN 1972 SAW A RECORD SETTING COLD STRETCH. CLOUD COVER FRIDAY NIGHT WHILE THIN LOOKS LIKE IT WILL BE ENOUGH TO KEEP TEMPERATURES SEVERAL DEGREES ABOVE RECORDS. SATURDAY NIGHT THOUGH COULD SEE LOWS OF 20 TO 25 BELOW ZERO IF CLOUD COVER BREAKS WHICH WOULD BE IN THE VICINITY OF THE RECORDS SET IN 1972. DEC 6-8 OF 1972 SAW RECORD SETTING LOWS OF: -20...-20...-25 IN BILLINGS/ CURRENT FORECAST -16...-20...-15 -28...-25...-39 IN SHERIDAN/ CURRENT FORECAST -19...-20...-13 -27...-23...-28 IN MILES CITY/ CURRENT FORECAST -23...-25...-18 -24...-21...-30 IN LIVINGSTON/ CURRENT FORECAST -19...-20...-12. CHAMBERS .LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED... ARCTIC COLD WILL REMAIN IN PLACE FOR MUCH OF THE LONG TERM AS MEAN 500-HPA TROUGHING CONTINUES OVER THE LOWER 48...KEEPING DEEP NORTH FLOW IN PLACE OVER THE REGION. FRESH AND DEEP SNOW COVER WILL WORK IN CONCERT WITH THE ANOMALOUSLY COLD AIR MASS TO KEEP TEMPERATURES WELL BELOW NORMAL...ESPECIALLY SAT WHEN HIGHS MAY NOT REACH 0 F IN AN AIR MASS CHARACTERIZED BY 850-HPA TEMPERATURES OF -21 TO -26 C. SOME LIGHT SNOW CHANCES ARE IN PLACE SAT ON THE NORTHERN SIDE OF A SHORT WAVE TROUGH CROSSING THE CENTRAL ROCKIES...AND ACROSS A GOOD PORTION OF THE AREA SUN THROUGH TUE WHEN GUIDANCE SHOWS SHORT WAVE IMPULSES DROPPING ACROSS THE REGION IN NORTHERLY FLOW ALOFT. A BIT OF MODERATION TO THE AIR MASS IS POSSIBLE AHEAD OF THOSE WAVES. BY THE MIDDLE AND LATTER PARTS OF NEXT WEEK...THE 00 UTC ECMWF AND GFS SOLUTIONS SUGGEST LARGE-SCALE FLOW WILL DEAMPLIFY AS THE RIDGE AT 500-HPA OVER THE NORTHEASTERN PACIFIC BREAKS DOWN. IF THIS DOES COME TO FRUITION...A WARMING TREND WILL BE IN THE OFFING AND WINDS IN THE FOOTHILLS WILL NO DOUBT STRENGTHEN. HOWEVER...EXISTING SNOW COVER...THE DEPTH AND GEOGRAPHIC EXTENT OF THE ARCTIC AIR MASS AND THE HISTORICAL TENDENCY FOR MODEL SIMULATIONS TO ERODE IT MUCH TOO QUICKLY ALL SUGGEST A COLDER-THAN-GUIDANCE TEMPERATURE FORECAST IS PRUDENT. THUS...OUR FORECAST LAGS MOS NUMBERS BY SEVERAL DEGREES F BY THE MIDDLE OF NEXT WEEK. SCHULTZ && .AVIATION... LOCALIZED MVFR STRATUS WILL BE POSSIBLE TODAY...OTHERWISE EXPECT VFR CONDITIONS. MVFR CONDITIONS WILL RETURN FROM KBIL W TONIGHT. ARTHUR && .PRELIMINARY POINT TEMP/POPS... TDY FRI SAT SUN MON TUE WED ------------------------------------------------------- BIL 902 916/908 920/906 915/010 905/012 001/020 016/027 1/I 13/S 32/J 22/J 33/J 32/J 11/B LVM 001 919/906 920/901 912/008 906/011 902/019 014/023 0/B 14/S 42/J 22/J 33/J 32/J 22/J HDN 902 918/907 920/906 916/007 907/009 001/018 012/025 1/I 12/S 32/J 22/J 32/J 22/J 11/B MLS 903 923/907 925/907 918/004 911/007 906/013 006/022 1/I 01/M 11/I 11/B 22/J 22/J 11/B 4BQ 903 920/906 921/905 916/005 910/008 906/014 008/024 1/I 01/M 22/J 21/B 22/J 22/J 11/B BHK 905 921/906 924/907 916/001 910/005 910/009 901/020 1/I 01/M 11/I 11/B 12/J 22/J 11/E SHR 901 919/905 920/901 913/010 906/012 901/021 009/025 0/I 13/S 32/J 22/J 33/J 22/J 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WIND CHILL ADVISORY IN EFFECT UNTIL 9 PM MST THIS EVENING FOR ZONES 31>33-36-37. WY...NONE. && $$ WEATHER.GOV/BILLINGS