FXUS63 KBIS 230453 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1053 PM CST Fri Nov 22 2024 .KEY MESSAGES... - There is a 50 to 90 percent chance of light accumulating snow this weekend across the north, with chances decreasing towards the south. There is a 40 to 60 percent chance of at least 2 inches of snow along the Canadian Border. - Below average temperatures are expected through this weekend and into next week. Highs will mainly be in the 20s and 30s, and lows mainly in the single digits to teens above zero. Monday will be colder, with highs in the teens and 20s and overnight lows in the single digits above and below zero. - Even colder temperatures will be possible during the Thanksgiving Holiday weekend, with forecast daytime highs in the single digits above some locations, and overnight lows below zero. Well below zero wind chill temperatures are also possible. && UPDATE Issued at 941 PM CST Fri Nov 22 2024 Snow has spread east a bit further than previously forecast, but over most locations it remains quite light. For late evening update have broadened out snow chances, but in line with latest guidance have the snow gradually tapering off as the night goes on. UPDATE Issued at 615 PM CST Fri Nov 22 2024 Light snow is starting to nudge into northwest North Dakota, on track with latest forecast. Will have to keep an eye on how this evolves over the next few hours as latest guidance has shown some differences on its evolution, with some models having it die out sooner than forecast. Otherwise, remainder of forecast continues to be in good shape. && .DISCUSSION... Issued at 211 PM CST Fri Nov 22 2024 Early this afternoon, a weak shortwave was noted on water vapor satellite imagery, moving through the region in low amplitude northwest flow aloft. An upper level ridge axis will move closer to the Montana/North Dakota border tonight behind another weak shortwave. Some of the guidance does suggest some decent midlevel frontogenesis but it is not forecast to lineup well with the diffuse synoptic forcing. Thus, we can expect medium to high chances (40 to 70 percent) of light snow across the northwest late this afternoon and into the evening hours but chances will quickly fall off when the wave moves into the central part of the state overnight and the frontogenesis washes out. Light accumulations associated with this wave will generally be confined to the northwest and will likely range from a dusting to around an inch at most. Lows tonight will range from the single digits above zero north (below normal for this time of year) to the mid to upper teens south (around normal to slightly below normal). The ridge axis then moves across the state on Saturday which should keep western and central North Dakota dry for most of the day (the exception possibly across the northwest where we could see some light warm air advection snow in the afternoon). We will gradually transition to southwest flow aloft from west to east as the next trough approaches. An upper low will close off near the border of Alberta and southern Saskatchewan Saturday night, bringing the next chances for light snow accumulations through Sunday. The trend continues to keep most of the synoptic forcing and frontogenesis north of the International border with only minor snowfall accumulations in our area as the trough passes through. While we will continue to see medium to high chances (50 to 90 percent) for light snow along and north of Highway 2, chances for 4 inches or greater still only max out around 30 percent right along the Canadian border through Sunday. Further south, mainly in the Highway 200 to Highway 2 corridor, expect only low to medium chances (20 to 50 percent) for light snow. With all that said, the best guess is that we will see a swath of 1 to 3 inches of snow (NBM 25th to 75th percentiles) along and north of Highway 2 tonight through Sunday and that may even be a bit on the high side. Confidence in advisory level winter weather over the weekend continues to lower so we will take the mention out of the Hazardous Weather Outlook for this forecast package. After the trough moves out of our area by Monday morning, we generally transition back into mean northwest flow aloft through the rest of the period. A few weak waves will quickly move through the flow at times during the upcoming work week, but for now these waves are only leading to spotty low chances of light snow (10 to 20 percent). The bigger story will likely be the much colder temperatures, especially around Thanksgiving and into the holiday weekend. Highs on Saturday and Sunday will range from the lower 20s to the lower 30s. Then on Monday morning, we will see lows ranging from around zero northwest to around 10 above southeast. Highs on Monday will then only range from the lower teens to the lower 20s and we could see below zero low temperatures northwest and north central Tuesday morning. Further south, lows will only max out around 5 to 7 above. We may moderate a bit Tuesday and Wednesday afternoon (highs in the teens north to the 20s and lower 30s south) but an even colder airmass is expected to move in on Thanksgiving and into the holiday weekend. By Friday morning, we could see lows in the 10 to 15 below zero range across the north, maxing out only in the lower single digits above zero over the far south. The one caveat is that there are still some decent NBM temperature spreads as we move towards the end of the week, but it is basically the difference between cold and very cold for this time of year. For example, the NBM spread for the low temperature at Minot on Friday morning ranges from 2 above zero (75th percentile) to 10 below (25th percentile). Either way, wind chills should be well below zero most mornings through the week across all of western and central North Dakota. Looking ahead, the well below normal temperatures should continue through the weekend. Stay warm and be careful if traveling! && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1053 PM CST Fri Nov 22 2024 Widespread MVFR with localized IFR ceilings continue through much of western and central North Dakota, though many parts of north central North Dakota including the KMOT terminal remain VFR. In the meantime, some snow continues over parts of western into mainly south central North Dakota, resulting in reduced visibility to MVFR and IFR levels. The snow will dissipate later overnight as it moves east. Ceilings over most locations will gradually improve Saturday morning, but will again lower in the afternoon/evening as the next wave moves into the area, which will also bring snow to northern locations reducing visibility. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...JJS DISCUSSION...ZH AVIATION...JJS