FXUS63 KFGF 181137 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 537 AM CST Wed Dec 18 2024 .KEY MESSAGES... - Winter impacts from accumulating and blowing snow are expected this evening through Thursday for eastern North Dakota and into portions of northwestern and west central Minnesota. 60% chance for warning type impacts resulting in very difficult travel conditions. && .DISCUSSION... Issued at 349 AM CST Wed Dec 18 2024 ...Synopsis... Current satellite has an area of low stratus across portions of eastern North Dakota and into northwestern and west central Minnesota. Flurries are ongoing in areas of low stratus this morning, but no accumulation is expected. A cooler and quiet majority of the day is expected today before a clipper system begins to shift in from the northwest. Synoptic forcing and frontogentic forcing shift in later this evening and into the morning hours on Thursday bringing a swath of 2 to 8 inches of new snowfall across portions of eastern North Dakota and into northwestern and west central Minnesota. As the system shifts southeast through North Dakota gusty NW winds develop across portions of eastern North Dakota and into the Red River Valley. Winter impacts from accumulating and blowing snow are expected this evening and into Thursday for eastern North Dakota and into portions of west central and northwestern Minnesota. ...Winter impacts late today through Thursday... Upper level system moves through southern Canada and into North Dakota this evening and into Thursday bringing wintery impacts to portions of the CWA. Ahead of this system strong WAA and frontogentic forcing develop within north central and parts of eastern North Dakota. Synoptic level forcing will be prevalent and confidence is high on its appearance within the forecast area today and into Thursday. We are confident there will be a swath of 2-5 inches of snow within eastern North Dakota and into portions of west central and northwestern Minnesota. A narrow band develops along the frontogentic zone back towards north central North Dakota this afternoon. CAMS show the Devils Lake Basin seeing the higher snowfall potential later this evening, with confidence low on its exact placement. Some of the CAMS push the band further northward or slightly southward. This affects the exact location of the highest snowfall rates and thus confidence and predictability is low on placement of the narrow band. None the less, predictability is higher that some areas within the Devils Lake Basin see higher snowfall rates. HREF probabilities of over an inch per hour are 60-70% within the Devils Lake area, but drop off quickly as the band of snow pushes eastward. This would be due to guidance struggling to handle whether or not the frontogentic forcing remains strong or weakens as the system shifts southeast. Timeframe of the narrow band approaching the Devils Lake Basin is later this evening and into the early portions of Thursday morning. As we push further through the morning the frontogentic forcing looks to weaken slightly in some guidance (60%). This would result in less organized bands within the main synoptic forced snow bringing brief localized higher snowfall rates as the snow reaches the Red River Valley. Some scenarios (40%) indicate frontogentic forcing remaining stronger through the morning as it reaches the Red River Valley. This would increase the snowfall rates within the valley and thus snowfall totals. A wide swath of 2-5 inches can be expected within eastern North Dakota and into portions of west central and northwestern Minnesota, with localized higher areas of up to 8 inches in the Devils Lake Basin. If forcing continues to be strong as heavier snowfall rates last longer into the Red River Valley those chances of up to 8 inches would then be possible within the valley. As the system shifts through the area we start to wrap around CAA. Winds increase as the temps cool, with sustained winds around 30mph during the afternoon and evening hours Thursday for eastern ND and the Red River Valley. There may be an overlap of falling snow and winds later in the morning and into the early afternoon. If this where to happen we would see significantly reduced visibilities. Best chance for the highest winds will be back toward central and western North Dakota where CAA is stronger and winds shift faster toward the north. None the less, the combination of sustained winds of 30mph and gusts up to 35mph during the afternoon and evening hours for eastern ND and the Red River Valley increase the threat for significantly reduced visibilities and very difficult travel conditions. There is a 60% chance for warning type impacts within the Winter Storm Watch area due to snow accumulations and blowing/drifting snow. Post system, we are looking at continued northwesterly flow, with a weak system late Friday into Saturday. Upper level ridging starts to develop late weekend and into early next week increasing temperatures and decreasing chances for precipitation. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 537 AM CST Wed Dec 18 2024 MVFR conditions this morning, as low stratus continues across the sites. There is a chance for a few flurries this morning underneath the low stratus. We will see a break mid to late morning through a majority of the afternoon before snow starts to move in from the west. DVL sees the snow first around 23-01z, and GFK, TVF, and FAR around 01-03z. BJI sees the snow around the midnight hour. Snow may be moderate at times in the DVL area 05-10z, with visibility reductions to 1/2SM. Lower chances for moderate snowfall in the Red River Valley. Reductions to visibility are likely, with GFK, FAR, and TVF seeing down to 3/4SM at times 05-10z. There is a chance for 1/4SM or less for all sites but BJI 05-12z, but confidence is low in that occuring. Ceilings underneath the snow will be MVFR to IFR. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Storm Watch from this evening through Thursday afternoon for NDZ006>008-014>016-024-026>030-038-039-049- 052>054. MN...Winter Storm Watch from this evening through Thursday afternoon for MNZ001>003-027-029-030-040. && $$ DISCUSSION...Spender AVIATION...Spender