Expires:No;;255741 FXUS63 KBIS 261247 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 647 AM CST Fri Dec 26 2025 .KEY MESSAGES... - Areas of fog are expected today and tonight, with dense fog expected this morning from northwest into parts of central North Dakota. - There is a low (20%) chance of light freezing rain in far northwest and north central North Dakota tonight. - Medium to high chances of light snow and gusty winds are expected Saturday night, with very cold temperatures returning Saturday night through Sunday night. && .UPDATE... Issued at 647 AM CST Fri Dec 26 2025 Quick update to add Burleigh County to the Dense Fog Advisory based on recent observational trends. UPDATE Issued at 625 AM CST Fri Dec 26 2025 We expanded the Dense Fog Advisory into Emmons and McIntosh Counties based on recent observational trends, including the M1/4SM visibility being reported by the Linton AWOS. Otherwise, only minor changes were made to the forecast with this update. There are some radar echoes in eastern MT and far western ND in association with midlevel warm air advection and frontogenesis near a developing warm frontal zone, but dry air aloft sampled by the 12 UTC KBIS RAOB suggests the probability of measurable precipitation reaching the ground is low at this juncture. && .DISCUSSION... Issued at 359 AM CST Fri Dec 26 2025 Early this morning, a broad surface ridge axis extends across central ND, with transient, low-amplitude shortwave ridging aloft in the wake of the impulse that brought high-impact freezing rain to parts of the area late yesterday. Surface pressure falls are beginning from western Saskatchewan into northeastern MT in advance of the next upstream impulse aloft. An expansive stratus deck with areas of fog exists over much of the area, with the most significant/widespread dense fog being noted on the west edge of the ridge axis, and near the west side of the stratus deck, roughly from Williston to Watford City, Hazen, Glen Ullin/New Salem, and Fort Yates as of 09 UTC. Earlier we issued a Dense Fog Advisory from northwestern into parts of central ND, where ASOS/AWOS visibility observations and web cam imagery has shown the most widespread and relatively- persistent visibility of 1/2SM or less. That said, even within that corridor there has been some variability/fluctuations in visibility trends at times. This may be due to a somewhat shallow low-level moist layer, and/or subtle increases in mixing of the boundary layer as flow just above the surface starts to increase on the west side of the ridge axis. Nonetheless, the overall scenario favors continuation if not additional expansion of dense fog from northwest into parts of central ND, especially along and just west of the Missouri River where low ceilings intersect slightly higher terrain. A consensus of recent CAMs and GLAMP guidance favors this scenario as well, with medium probabilities of the dense fog further expanding to the east yet this morning. We will monitor observational trends in case any expansion of the Dense Fog Advisory is needed, e.g., into Burleigh and Emmons Counties. For later today, we expect stratus and fog to erode/dissipate in southwestern ND this afternoon as low-level wind fields increase in advance of an upstream shortwave trough. This, combined with a warm air mass aloft in a southwest flow regime means that high temperatures today are forecast to be well into the 40s F if not around 50 F in southwestern ND, e.g., for the Beach, Dickinson, Bowman, and Hettinger areas. How far north and east stratus and fog is able to erode is somewhat uncertain, but the overall air mass characteristics and slowly shallowing low-level moisture do support highs exceeding 32 F in south central ND, including in the areas that received freezing rain yesterday. Guidance would suggest that fog may persist in some fashion in northwest and north central ND into the James River valley through the day, though slow warming of the boundary layer (albeit with highs in those areas mainly in the mid/upper 20s F) is apt to result in increasing visibilities after 18 UTC. We have a dry forecast in place area-wide today, but by this evening a low, 20 percent chance of freezing rain exists in far northwest and north central ND, near the Canadian border. That low chance of light freezing rain continues in those areas into the overnight hours. That is supported by low- and midlevel warm air advection near a sharpening midlevel warm frontal zone, with increasing differential cyclonic vorticity advection aloft given height falls and strengthening/sharpening southwest flow aloft. Forecast soundings near the Canadian border display a warm nose aloft from +4 to + 7 C atop sub-freezing surface temperatures in support of a conditional freezing rain scenario. However, it is very important to point out that those forecast soundings also display a deep dry layer aloft, which is why most model guidance fails to simulate significant precipitation on the North Dakota side of the U.S./Canadian border, and why our precipitation chances are only around 20 percent at this juncture. One other feature worth noting tonight is a strong upper-level jet streak on the order of 120-140 kt, which will have its left exit region focused in western and central ND. While significant dry air is expected aloft, this presents a low, but non-zero (approximately 10 percent) chance of light precipitation further south into southwest and central ND overnight tonight. These odds are too low to even mention in the official forecast at this juncture, but the 00 and to a lesser degree 06 UTC HRRR cycles capture this in simulating some light precipitation moving through southwest and into central ND tonight. This will be a low probability, highly-conditional scenario contingent on sufficient saturation that's more than simulated by most models, but one that would be manifest as light freezing rain if it did come to fruition. Again, though, this is a low probability scenario that's too small to even be in the official forecast at this time. Otherwise, patchy to areas of fog may persist and/or redevelop in central ND and the James River valley tonight, though winds just above the surface are forecast to increase and veer with a drying tendency such that the prospects for persistent and dense fog may actually be greatest in the evening before decreasing after 06 UTC. At this time we are simply mentioning patchy to areas of fog in the forecast tonight into Saturday morning. On Saturday, highs are forecast to range from the teens and 20s F in northwest and north central ND, to the lower 40s in southwest ND. However, the main feature of interest will be the late-day and evening passage of an Arctic cold front and strong shortwave trough aloft. Medium to high chances of light snow are expected to accompany the frontal passage centered on Saturday night given the frontal forcing and thermal profiles that cool into the dendritic growth zone. However, any accumulations would be minor. Strong low-level cold air advection is expected with the frontal passage, and at least moderate surface pressure rises are also expected, favoring a period of wind gusts up to around 40 mph. The current suite of guidance, including recent forecast EFI values, suggest the odds of reaching Wind Advisory criteria with the frontal passage are low to medium. The arrival of Arctic air may result in wind chills around -30 F in parts of the area Saturday night through Monday morning, especially in northern parts of the state. Cold Arctic air is forecast area-wide on Sunday with highs only in the single digits above zero in most areas, with the spread in ensemble guidance low in that timeframe. Northwest flow aloft is expected to develop during the early and middle parts of next week, with a low-level baroclinic zone and associated gradient/ sharp contrast in surface temperatures across the region. This becomes very pronounced by Wednesday (New Years Eve), when the ensemble 25th-75th percentile spread in high temperatures across most of the area remains extreme, on the order of thirty to forty degrees, ranging from highs around -5 F to +35 F. This stems from how sharp and prolonged northwest flow remains, which itself is tied to how quickly a trough in the eastern Pacific Ocean progresses eastward. Ensemble clusters suggest there's a 60% probability of the more prolonged northwest flow persisting due to a more slowly-approacing upstream trough, which would result in a colder scenario by midweek, and a 40% probability of the warmer scenario occurring. Regardless, it's important to note that the official forecast largely represents the mean of an atypically large spread in potential outcomes with regard to temperatures by the middle to latter parts of next week. Low to medium snow chances also exist in the early and middle parts of next week given the presence of the low- and midlevel frontal zone across the area, albeit with the same uncertainty in its location, and also timing of any impulses that would generate more focused precipitation along the cool side of the boundary. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 625 AM CST Fri Dec 26 2025 Widespread IFR to LIFR conditions in stratus and fog will impact northwest and central ND through much of the 12 UTC TAF cycle. Dense fog with visibility as low as 1/4SM is expected through this morning in parts of northwest and central ND, including at KXWA. There may be some improvement in ceilings and visibility between about 18 and 00 UTC before conditions deteriorate again. The KXWA to KBIS corridor will be near the back edge of low clouds and fog tonight, lowering confidence in the exact details of those TAF forecasts. In southwestern ND, patchy fog and localized low ceilings will produce brief MVFR to IFR conditions this morning, but then we expect VFR conditions to prevail this afternoon and tonight as the back edge of the main area of low clouds and fogs advances north and east toward a location roughly near the Missouri River by this afternoon and evening. && .BIS WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until noon CST /11 AM MST/ today for NDZ001- 002-009-010-017>021-034-035-042-045-046-050. && $$ UPDATE...CJS DISCUSSION...CJS AVIATION...CJS