363 FXUS65 KTFX 061119 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 419 AM MST Sun Jan 6 2013 .DISCUSSION... Today through Tuesday...Expect a rather changeable weather pattern to reside over the region for the next few days. Even though no significant snowfalls are expected, accumulating snow will occur over the Rocky Mountain Front along with windy conditions east of the divide and out over the Northern Plains. As an upper level disturbance moves through today, expect fairly strong winds over the northern Rocky Mountain Front. The wind gust should be just below warning criteria today, so no highlights will be issued at this time. Light snow is also expected along the divide. 1 to 2 inches of snow is possible in the mountains today...with an additional 1 to 2 inches possible tonight. Afternoon temperatures today will be mild along the front range, but pockets of colder air still exists over the region, such as in the West Yellowstone, Helena, and Havre areas. On Monday, a weak Pacific warm front will move eastward through the region. Expect a band of snow to accompany the frontal passage. The snow should be light out over the plains, and a bit scattered. There is the small potential for a mix of snow/freezing rain on the back edge of the precip, especially over Southwest Montana from late Monday night into Tuesday morning. For now I will hold off on putting in freezing rain in the forecast, but continue to monitor the potential closely. Warmer and windier conditions can be expected on Tuesday. Most areas, including the valleys of Southwest MT should mix out and warm up a bit, with the warmest readings expected over the Plains of North Central MT. Brusda Tuesday night through Sunday...The period starts out with a weak upper ridge over the area. A weak impulse moving through the ridge position Tuesday night will bring light snow to the Rocky Mountain Front. The flow aloft becomes increasingly southwest on Wednesday as an upper trof digs along the west coast. Moisture and instability will increase over southwest Montana with scattered snow developing over the southwest and western mountains. A fairly deep lee side trof will contribute to gusty winds along the east slopes of the Rockies and over the adjacent plains Tuesday night through Wednesday. By Thursday, the upper trof will push across the continental divide. The models differ a bit on the trof orientation. The GFS shows a split trof with most of the energy associated with the southern branch over central California. The European model maintains more of an open wave configuration. Regardless, both models bring scattered snow to the area. Cold advection associated with the upper trof will drop temperatures to below seasonal averages on Thursday. The upper trof continues to reside over the area Friday with scattered snow continuing. Again, the models differ with their solutions, the GFS maintaining a split configuration and less precipitation. A broad upper trof aloft and a northerly to northwest flow aloft Saturday and Sunday will bring mainly mountain snow showers and cold temperatures over the plains. Temperatures will remain above seasonal averages Wednesday but will drop 10 to 15 degrees below seasonal averages for the remainder of the week. Highs will be generally in the teens to lower 20s with lows in the single digits. && .AVIATION... Updated 0530Z. Mid and high level clouds will continue to increase overnight as a shortwave trough approaches the Northern Rockies. Snow will become likely over the Continental Divide from Glacier Park south to MacDonald Pass by 12Z with widespread obscurations expected. VFR conditions will prevail at all terminals with skies remaining mostly cloudy through much of the period. Gusty westerly winds are expected over north central Montana, especially after 18z, but will diminish after 00Z Monday. MPJ && .PRELIMINARY POINT TEMPS/POPS... GTF 41 26 40 32 / 10 10 20 30 CTB 38 21 36 28 / 10 20 10 30 HLN 29 14 30 22 / 10 20 20 30 BZN 27 7 27 18 / 10 20 20 30 WEY 22 -2 20 9 / 10 20 30 40 DLN 32 11 31 19 / 10 10 20 30 HVR 33 18 35 24 / 10 10 20 10 LWT 40 18 35 26 / 10 10 20 30 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls