NZUS95 KTFX 192028 LLLTFX MTZ301>330-200828- Public Information Statement National Weather Service Great Falls MT 128 PM MST Tue Nov 19 2024 Key Points Today will be the warmest day of the week with cooler temperatures expected the rest of the work week. Widespread snowfall is expected Thursday night through Sunday morning with freezing rain possible in Central Montana early Friday morning and early Saturday morning. Sunday through next Tuesday colder temperatures are expected with near zero lows likely in North-central Montana. Meteorological Overview An upper-level trough remains over North-central, Central, and Southwestern Montana today. Then an upper-level ridge moves over the area on Wednesday and remains there through Saturday. On Wednesday due to an upper-level low of the Pacific Coast there will be snow along the Northern Rocky Mountain Front.Thursday through Saturday morning a stationary front will be situated over North-central/Central Montana. This will allow cooler air to move south from Canada into North-central and Central Montana. This brings precipitation chances to the area Thursday through Saturday morning with mostly snow for North-central Montana, a rain/snow mix for Central Montana, and rain for Southwestern Montana. Due to warm air advection overrunning the cold surface air Thursday night into Friday morning and Friday night into Saturday morning there is the potential for freezing rain in North-central and Central Montana. See the Forecast Confidence & Scenarios section below for more details. On Saturday an upper-level trough begins to move over the area and the stationary front transitions to a cold front which moves south through North-central, Central, and Southwestern Montana this will bring widespread snow to the area Saturday morning through Sunday afternoon. The upper-level trough will remain over North-central, Central, and Southwestern Montana on Sunday. The trough appears to remain over the area through at least Tuesday. This will bring colder temperatures to North-central, Central, and Southwestern Montana on Sunday through at least next Tuesday. See the Forecast Confidence & Scenarios section below for details. Forecast Confidence & Scenarios There is a high confidence in snow along the northern Rocky Mountain Front on Wednesday. There is low confidence in freezing rain Thursday night into Friday morning and Friday night into Saturday morning in North-central and Central Montana due to uncertainty in the position of the stationary front and how much warm air will be present aloft. If the freezing rain doesn’t occur then if precipitation falls it would be light snow instead. There is low to moderate confidence in snow across North-central and Central Montana Thursday night through Saturday morning and high confidence in snow Saturday through Sunday morning. In Southwestern Montana there is moderate to high confidence in snow Saturday morning through Sunday morning. On Wednesday there is a 50 - 75% chance for 2 inches or more snow along the Northern Rocky Mountain Front. On Thursday there is a 15 - 40% chance for a tenth of an inch snow or greater in the plains of North-central Montana. On Friday there is a 5 - 30% chance for an inch of snow or greater in North-central Montana. Thursday evening to Friday evening there is a 10 - 30% chance for a hundredth of an inch of ice accumulation in North-central and Central Montana. Friday evening to Saturday evening there is a 10 - 20% chance for a hundredth of an inch of ice accumulation in North-central Montana. Thursday evening through Sunday evening there is a 40 - 60% chance for 2 inches of snow or greater in the plains of North-central and Central Montana. There is high uncertainty in the duration of the upper-level trough remaining over the area on Monday and next Tuesday. On Monday and next Tuesday two of the clusters have an upper-level ridge building back over North-central, Central, and Southwestern Montana. This scenario would begin to warm temperatures back up on next Tuesday. On next Tuesday the other two clusters keep an upper-level trough over North-central, Central, and Southwestern Montana. This scenario would keep the colder temperatures for the area. However there is high confidence that Sunday and Monday will be cold. There is a 30 - 60% chance for low temperatures of zero or below on Sunday morning along the Hi-Line and in the Golden Triangle Region (Cut Bank to Havre to Great Falls). Due to snow cover and model differences, how cold locations will get Monday morning varies. There is a 40 - 80% chance of temperatures at or below zero on Monday morning along the Hi-Line and the Golden Triangle Region. -IG