630 FXUS63 KUNR 102126 AFDRAP AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 230 PM MST FRI DEC 10 1999 LIGHT SNOW IN NE WY HAS ALMOST ENDED AS A SMALL SHORT WAVE THAT CAN BE SEEN ON WATER VAPOR HEADS TO THE NE. 06Z MESO-ETA AND THE 18Z MESO-ETA DID A GOOD JOB OF DISPLAYING THIS SHORTWAVE WHILE THE OTHER MODELS SMOOTHED OVER IT PLACING IT WITH THE MAIN SHORT WAVE THAT STRETCHES FROM ALBERTA/SASKATCHEWAN BORDER SOUTHWARD INTO WESTERN WYOMING DOWN TO WESTERN ARIZONA. AS THIS LONG WAVE TROF PASSES OVER THE REGION TONIGHT CLOUDS WILL DECREASE AS DRIER AIR AND SUBSIDENCE FILL IN BEHIND IT. WITH DECREASING CLOUDS AND CAA AT 850 AND 700 MB TONIGHTS LOWS WILL BE COLDER THEN LAST NIGHTS. BUT BY SUNDAY MORNING THE 850 AND 700 MB TEMPERATURE PATTERN CLOSELY RESEMBLES WHAT WE HAD THIS MORNING AND TEMPERATURES WILL BE WARMER AGAIN. HIGH PRESSURE MOVES INTO THE REGION SATURDAY AFTERNOON AND REMAINS OVER THE AREA THROUGH MONDAY. TIME HEIGHT SECTIONS ARE SHOWING LITTLE IN THE WAY OF RH ON SATURDAY...WITH AN INCREASE ABOVE 500 MB BY SUNDAY MORNING IN THE WESTERN ZONES. THEREFORE WILL PUT PARTLY CLOUDY IN THE FORECAST FOR SATURDAY WITH MOSTLY CLOUDY ON SUNDAY. AS FOR TEMPERATURES...FWC AND FAN ARE WITHIN A DEGREE OF EACH OTHER. I THINK THAT SUNDAYS FORECAST OF MID 50S FOR KRAP ARE A BIT OPTIMISTIC THOUGH. WITH DENSE CIRRUS OVER THE AREA THERE WONT BE MUCH SUNLIGHT TO WARM US UP AND THE WAA IS NOT THAT STRONG. A WEST WIND MAY HELP PROVIDE SOME DOWNSLOPE AND HEATING BUT I STILL FEEL THE NUMBERS ARE TOO HIGH. IN THE EXTENDED...THE EUROPEAN AND MRF BOTH ARE SHOWING A TIGHTLY WOUND SURFACE LOW BY TUESDAY MORNING OVER NORTHWESTERN NORTH DAKOTA. WILL LEAVE THE MENTION OF WINDY IN THE FORECAST AFTER THE COLD FRONT PASSES THROUGH. AS THE SURFACE LOW AND UPPER LEVEL SHORTWAVE MOVE TO THE EAST...WE GO FROM A ZONAL PATTERN TO A MORE NORTHWESTERLY MERIDIONAL PATTERN AT 500 MB. SIGNIFICANT CAA IN STORE FROM MONDAY EVENING (+6 CELSIUS 850 TEMP) THROUGH THURSDAY A.M...WITH COLDEST TEMPERATURES SO FAR THIS SEASON BY THURSDAY MORNING. (507 THICKNESS OVER MOST OF THE CWA THU A.M. WITH -15 CELSIUS 850 MB TEMPS) THE DIFFERENCE BETWEEN THE TWO MODELS IS ON WEDNESDAY. .UNR...NONE. FRANSEN