618 FXUS63 KBIS 210222 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 922 PM CDT Sun Mar 20 2022 .UPDATE... Issued at 921 PM CDT Sun Mar 20 2022 For this update, have blended in current conditions and adjusted pops a little on the western border. Regional radar mosaic shows the stronger returns in eastern Montana, and a few reporting locations (Wolf Point, Miles City) have reported light rain in the past hour under those stronger reflectivities. High resolution model solutions continue to suggest the best precipitation chances initially will be along the Montana border, so increased pops a bit in my west to better align with my neighbors. We also brought in small pops to the southwest a bit faster based on light returns moving north out of South Dakota on the Bowman radar. Winds have begun to increase from the northwest in the western part of the state. KXWA has gusted to around 35 mph which is in line with some of the higher gusts being reported in eastern Montana. The current forecast has that covered well, so only made minor adjustments. UPDATE Issued at 642 PM CDT Sun Mar 20 2022 Late afternoon surface analysis placed low pressure across northwest/north central South Dakota with an inverted trough into western North Dakota. The low is expected to gradually move east tonight into Monday. This could bring a chance of rain/snow to western North Dakota later this evening. The main change for this forecast update was to add small pops to the far northwest corner of the state a couple hours earlier than in the previous forecast. Hi-resolution model solutions have been fairly consistent in suggesting at least a small chance in that area in the coming hours. Otherwise, the timing still looks good with the best chances for most areas holding off until after midnight. In regards to snow amounts, the current forecast again looks to be on track. NBM 4.1 snow amounts over the 24 hours ending at 00Z Tuesday are generally in line with the current forecast, showing the higher amounts towards the Turtle Mountains. The 90th percentile has less than an inch for most locations with again the higher amounts of an inch or two towards the Turtle Mountains. Looking at the 10th percentile, it basically shows a dry outcome. It's entirely possible some locations don't get much at all from this system, espcially with the fairly dry looking 90th percentile in the far south central towards the James River Valley (south of Jamestown). Winds are a bit tricky with them weakening in the inverted trough, but they are gusty in the stronger pressure gradient ahead and behind it. In general the stronger gusts have been around 35 mph which is covered well by the going forecast. && .SHORT TERM...(This evening through Monday) Issued at 131 PM CDT Sun Mar 20 2022 The main forecast issue in the short term period will be precipitation chances and winds tonight and Monday. Currently, low pressure was situated over northwest South Dakota with an inverted trough north northwest into far northeast Montana. A rather tight pressure gradient extended east across the forecast area with winds around 20 mph with gusts up to around 35 mph over central ND. Winds have been diminishing over western ND closer to the inverted trough. Skies were partly to mostly sunny across the area with mainly high thin clouds. Tonight. the surface low and inverted trough will propagate slowly eastward, with the inverted trough situated around the Highway 83 corridor by around midnight. The strong southeast winds will slowly diminish over central ND this evening. In western ND there will be a period of stronger northwest winds this evening on the back side of the inverted trough. These stronger northwest winds could sneak into central ND later this evening as well. All of these winds are expected to remain below advisory criteria. Precipitation chances finally arrive late tonight with the mid and upper level trough. Small precipitation chances arrive in the far west late this evening, with better chances holding off until after midnight, then crossing the Highway 83 corridor early Monday morning, and moving into the Turtle Mountains and James River Valley by mid to late morning Monday and tapering there by mid afternoon. Precipitation will start out as rain this evening, but as temperatures drop later tonight, expect mostly a mix of rain and snow, with more rain west and south central and more snow north central. These precipitation amounts are going to be light too. Most areas will see less than a tenth of an inch, and many seeing only a trace to a couple hundredths. The Turtle Mountains area might see some of the higher qpf totals Monday and they should be cold enough for all snow early then a rain snow mix late morning and on. This area could around an inch of snow, most areas that get any snow only receiving a trace to a few tenths of an inch. It will be noticeably colder and breezy Monday. After lows tonight in the low to middle 30s, highs will only climb into the mid 30s around the Turtle Mountains, to near 50 along the South Dakota border. .LONG TERM...(Monday night through Sunday) Issued at 131 PM CDT Sun Mar 20 2022 If precipitation hasn't already ended over eastern portions of central ND by Monday evening, it will end early Monday evening. Otherwise mainly dry conditions are expected Tuesday through Thursday. Another wave moves through the Northern Plains during the Thursday night through Friday timeframe bringing a small chance of precipitation. This is followed by upper level ridging through next weekend. After temperatures mainly in the 30s and 40s for Tuesday and Wednesday, we rise into the 50s on Thursday ahead of the aforementioned wave that cools us back down into the 40s on Friday. We then warm back into the upper 40s and 50s for most areas by Sunday, with lower 60s possible over the far southwest. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 642 PM CDT Sun Mar 20 2022 An area of low pressure moving across South Dakota will bring a chance of rain/snow to western and central North Dakota tonight and Monday. The precipitation will move from west to east, so the first TAF locations to have precipitation chances will be in the west. Confidence in fairly low in regards to precipitation intensity and potential visibility restrictions. For now, will generally suggest P6SM, but monitor as things develop. More confidence comes in the potential for lower (MVFR and perhaps IFR) ceilings. Winds will turn to a northwesterly direction as the low crosses the region. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...King SHORT TERM...TWH LONG TERM...TWH AVIATION...King