FXUS65 KTFX 140504 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1004 PM MST Thu Feb 13 2025 Aviation Section Updated. .KEY MESSAGES... - Light snow and blowing snow will continue through this evening for the Ennis and Monida Pass areas. - Cold temperatures are slow to mix out of the valleys of Southwest MT and areas north of Havre. - Light snow moves northward through the CWA overnight. - Widespread snow is expected Friday afternoon and night, some of which could be heavy in the Bozeman and Big Sky areas. - Two rounds of additional snow are expected early next week, one Sunday and another Monday. - Generally cold temperatures expected to continue through much of next week as well. && .UPDATE... /Issued 912 PM MST Thu Feb 13 2025/ Initial wave of moisture is lifting north through central MT this evening with some areas of very light snow or flurries. This weakening disturbance continues to lift across north-central MT overnight before stalling near the Hi-line Friday morning. Gusty south winds are still bringing some blowing and drifting snow impacts to areas near the ID border, where a winter weather advisory remains in place through midnight. Winds and associated blowing/drifting snow in these areas are expected to gradually decrease through the overnight period as mid-level flow weakens. Cold air and surface high pressure is rebuilding south and west across the north-central MT plains, resulting in enhanced easterly winds across much of Hill and Blaine counties overnight. This combined with temperatures falling to the single digits below zero may push wind chills to less than -20F at times later tonight. Hoenisch && .DISCUSSION... /Issued 912 PM MST Thu Feb 13 2025/ - Meteorological Overview: The first in a series of weather disturbances is expected to affect the CWA overnight tonight and into Friday morning. This disturbance tonight will be weak, thus just a few scattered snow showers are likely. On Friday, a stronger wave of moisture will move northward into the region. This wave of moisture is connected to the atmospheric river moving into CA currently. There is the potential for a bit heavier snowfall with this system in the Bozeman/Big Sky area by Friday evening and then continuing into Friday night. Snowfall will push northward into North Central MT, but lighter snow amounts are expected. For Sunday and Monday...the flow aloft will be a bit more northwesterly, with upper level disturbances moving through the CWA. Each disturbance could produce some light snow, but the mountains of Central MT could be near warning criteria for Sunday into Monday. The widespread snow mostly ends by Tuesday, with scattered mostly mountain snow showers expected towards the middle/later portions of next week. In terms of temperatures, the valleys of Southwest MT have been slow to warm, however with increasing cloud cover and some precipitation, warmer air from aloft will start to mix down a bit when it snows, and the cloud cover overnight will prevent temperatures from falling too far over the next few nights. This is also true for areas north of Havre along Highway 2, where it continues to be cold as well. Overall though, temperatures will be below normal everyday through next week, but just not quite as cold as it has been through Monday. With some clearing moving into the CWA by Tuesday, overnight lows look to be in the 20 below or colder range by the middle portion of next week. - Forecast Confidence & Scenarios: There are a few concerns over the next few days with the first one being accumulating snowfall on Friday in the Bozeman area, where some forecast models prog about an 8 inch snowfall. Right now there is about a 50 percent chance for 4 inches of snow in Bozeman. For Sunday into Monday, there is a 50 percent chance that the mountain areas of Central MT could get near 10 inches of snowfall, including Kings Hill and the Big Snowy Mountains. Snowfall at lower elevations generally looks to be in the 1 to 3 inch range. Additionally, as cold temperatures return by next Tue into Wed, there will be the potential for cold temperature statements once again. Brusda && .AVIATION... 14/06Z TAF Period A band of snow with periods of mountain obscuring MVFR/IFR conditions currently over Central Montana will continue to move north into North Central Montana through 09Z. Snow is forecast to decrease over Central Montana after 08Z over Central Montana, but the band of snow is forecast to linger over North Central Montana through at least 15/06Z. Despite the decrease in snow, a shift to more northerly winds over the plains will continue mountain top obscuring low VFR/MVFR ceilings over Central Montana. Another surge of moisture is then forecast to spread more snow with widespread mountain-obscuring MVFR/IFR conditions over the area from 17Z through 15/06Z. -Coulston Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .HYDROLOGY... The flood advisory continues for the Madison River in Ennis because of an ice jam. Over the past few days, emergency manager in Ennis reported the ice jam is slowly getting a bit worse as the ice jam continues to grow. The minor flooding is starting to grow eastward towards Odell Creek, along with southward towards Highway 287. There is some potential that the ice jam could result in water going over Highway 287 if the ice jam continues to grow. Thus the flood advisory will continue until the ice jam breaks and the water recedes. Brusda && .PRELIMINARY POINT TEMPS/POPS... GTF 3 8 -1 8 / 60 60 90 10 CTB -3 4 -8 4 / 40 60 50 0 HLN 1 14 3 21 / 70 70 80 10 BZN 3 22 5 21 / 20 60 100 40 WYS 10 31 11 26 / 70 70 100 50 DLN 7 31 13 28 / 10 20 50 0 HVR -3 9 -7 3 / 20 60 90 0 LWT 2 10 -4 7 / 30 60 90 20 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 3 PM Friday to 10 AM MST Saturday for Bears Paw Mountains and Southern Blaine-Cascade County below 5000ft-Fergus County below 4500ft-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Meagher County Valleys- Western and Central Chouteau County. Winter Storm Watch from Friday afternoon through Saturday morning for Big Belt, Bridger and Castle Mountains-Gallatin Valley-Gallatin and Madison County Mountains and Centennial Mountains. Winter Weather Advisory until midnight MST tonight for Madison River Valley-Ruby Mountains and Southern Beaverhead Mountains. && $$ http://www.weather.gov/greatfalls