FXUS63 KBIS 032335 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 535 PM CST Mon Feb 3 2025 .KEY MESSAGES... - Very cold wind chills as low as 35 below are expected through Tuesday morning, especially across northern North Dakota. Below average temperatures are forecast to remain through the work week. - A round of snow moves through tonight through Tuesday, bringing 1 to 2 inches of snow to the northwest, and lower accumulations elsewhere. - There are additional chances for snow on Wednesday (60 to 90 percent) and at the end of the week (30 to 50 percent). && .UPDATE... Issued at 535 PM CST Mon Feb 3 2025 Generally quiet weather is currently found over western and central North Dakota this evening. An area of weak reflectivities can be found across the south west and south central, though no associated observations of snow can be found. A more robust area of reflectivities is building across the border in western South Dakota, and is expected to represent the next round of snowfall that will expand across western and central North Dakota later this evening and overnight. Otherwise, temperatures this evening are from around 15 below zero northwest up to around 0 in the southern James River Valley. Winds chills generally remain less than 30 below zero north of Highway 200, and less than 20 below zero elsewhere. The sky remains partly to mostly covered as high based clouds linger across the northern Plains. No major adjustments to the forecast were necessary at the time of this update, as it remains on track. && .DISCUSSION... Issued at 251 PM CST Mon Feb 3 2025 Zonal flow aloft dominated the synoptic pattern this afternoon, with a stout surface high pressure building in from the Canadian Prairies. This high is helping scour out low clouds from north to south, although additional high clouds are coming upstream from an approaching wave. With a tightened pressure gradient, northwest winds have been persistently gusty, especially in the north central through the James River Valley. We have a Special Weather Statement in effect through mid-afternoon for blowing and drifting snow due to the strong winds and fresh snowpack. Visibilities are occasionally dropping under a mile, but we do expect that winds will start tapering off later in the afternoon which should help diminish the blowing snow potential. It's quite cold this afternoon, with highs close to 10 degrees below zero northwest, to around 10 above southeast. Overnight lows are forecast to drop into the 15 to 20 degrees below zero range across northern North Dakota, where a Cold Weather Advisory remains in effect, with wind chills down to 35 below zero. Additionally, snow chances return early this evening as an embedded wave tracks through southwest flow aloft as weak ridging builds over the Northern Rockies. Expecting this to be a relatively light snow event, with a general 1 to 2 inches of fresh snow in northwest, and an inch or less elsewhere. QPF looks light but with snow ratios around 20:1, if not a little higher, it won't take much for a bit of accumulation tonight through Tuesday morning. Snow chances taper off Tuesday evening, with highs in the single digits. A more substantial wave is progged to skirt the International Border Wednesday into Thursday, with blended POPs producing widespread 70 to 90 percent chances for snow, peaking Wednesday afternoon. The highest probabilities for accumulating snow have consistently been in northern North Dakota over the past few days, with a medium to high chance for at least 3 inches of snow in our northern counties, and lower probabilities to the south. There is a low (15%) chance for exceeding 6 inches of new snow in this area, but the progressive nature of the wave and current lack of banded snow ingredients in deterministic guidance gives confidence that snow amounts that high are an unlikely outcome. We finally get a break from accumulating snow on Thursday as a surface high moves in, although elevated surface winds does produce concern for blowing and drifting snow, with a fresh, fluffy snowpack and cold temperatures. The ECMWF EFI does have some signal for enhanced winds across the north and east, which is where the NBM is advertising strongest winds, so this will be a hazard to keep an eye on in the coming days. The active pattern continues to end the week, with good agreement among ensemble members on a shortwave trough moving through the Northern Plains. Clusters show similar scenarios of a broad west- east QPF axis somewhere across the Dakotas, with blended POPs already advertising a 40 to 60 percent chance of snow across the forecast area Friday night into Saturday morning. There is high confidence in temperatures staying below average through this week and into next week. By Wednesday, highs wil range from the single digits above zero north to the teens south, with that general temperature range expected through the weekend. There are signs of a colder air mass moving into the region to start next week, with a 70 to 80 percent chance of below normal temperatures continuing through the following weekend. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 535 PM CST Mon Feb 3 2025 VFR ceilings and visibility can be found at all terminals to begin the 00Z TAF period. Another round of light snow is expected to move in from the southwest this evening, expanding to include much of western and portions of central North Dakota through Tuesday morning. Generally MVFR conditions are expected where light snow does fall, though IFR conditions are also possible if and where more moderate snowfall develops. Breezy northwest winds will generally diminish and turn easterly overnight through Tuesday afternoon. && .BIS WATCHES/WARNINGS/ADVISORIES... Cold Weather Advisory until noon CST /11 AM MST/ Tuesday for NDZ001>005-009>013-017>019-021>023-025. && $$ UPDATE...Adam DISCUSSION...Jones AVIATION...Adam