FXUS63 KFGF 100329 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 929 PM CST Sun Feb 9 2025 .KEY MESSAGES... - Bitterly cold wind chills expected this week. Wind chills will fall into the minus 30s Monday morning and likely minus 40s on Tuesday and Thursday. && .UPDATE... Issued at 928 PM CST Sun Feb 9 2025 Isolated flurries have cropped up below stratus, but impacts will be limited as no accumulations or impacts to visibility have been observed. Other than that, expect wind chills to get at least to 20 below, with 30 below expected in the Devils Lake Basin. UPDATE Issued at 622 PM CST Sun Feb 9 2025 Convective snow showers developed late this afternoon on the periphery of a differential diabatic heating boundary between snowpack and no snowpack in the central Red River Valley. These have diminished for the most part now that the sun is setting. Overnight temperatures will remain fairly low in the 5 to 10 below range, with the coldest temperatures in the Devils Lake Basin and south of I-94 because of recent snowpack. Close monitoring will be necessary down there for potential expansion of the Cold Weather Advisory as air temperatures will be fairly cold and may push it to the 30 below range for apparent temperature. && .DISCUSSION... Issued at 117 PM CST Sun Feb 9 2025 ...Synopsis... Progressive Hudson Bay troughing to the northeast and stout Gulf of Alaska riding in the NW Pacific are currently yielding weak shortwave troughing across the Canadian prairies and north central US. This will gradually transition to a more amplified NW flow regime on the lee of the Canadian Rockies with cold air intruding across the Canadian border. By mid week deep layer troughing develops across the Hudson Bay fixing the pattern into a locked state until Pacific troughing undercuts the Alaskan ridge and allows spilt flow in the mid levels with flow in the northern plains becoming more zonal aloft cutting off the supply line of the colder continental polar airmass with a modified maritime polar airmass traversing the Rockies and bringing increasing precipitation chances late week into the weekend. - Cold air This will be the third solid cold snap of the season with one in late November around Thanksgiving and then another back a few weeks ago in mid January. This will fall in between the two in terms of severity of cold with a similar duration of cold to the January cold snap. Conveniently we just had a fresh swath of 4-8' of snow for most locations south of I-94 in North Dakota and HWY 10 in Minnesota. This will serve to help the cold air reach its full radiational cooling potential in the overnight periods tonight through next weekend as lows fall into the minus single digits to minus teens each night through next weekend. Tuesday and Thursday look particularly cold as they show the highest probability of lows falling past -20 on a more than local basis. Currently have a wind chill advisory in effect tonight for the Devils Lake basin with a plan to issue a more long fused product starting sometime Monday afternoon/evening to cover the extended duration sub -30 wind chills. Shorter duration Extreme Cold Warnings may be needed throughout the next several days but will likley not cover consecutive days or nights with enough of a daytime rebound in dangerous wind chills. - Late week snow chances As upper flow becomes more zonal and progressive Thursday into Friday a wave will traverse the northern CONUS tracking through the upper Midwest bringing a 25% chance for up to 1" to start the weekend. As for other wintery impacts such as blowing snow it appears to be a notably calm period in terms of winds with Monday afternoon seeming to foster the best potential for some drifting mainly north of HWY 200 throughout northeast North Dakota. Maybe 10- 20% of the area would see any drifting as this area is particularly wind scoured/crusted per polar orbiting satellite passes from yesterday, so any drifting will come from the patchy blowable snow in the area. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 504 PM CST Sun Feb 9 2025 Scattered snow showers will continue through 01z in the vicinity of TVF but this will diminish after sunset. Generally VFR conditions will be expected once sunset happens with only a few isolated pockets of MVFR possible at DVL. Winds will increase in intensity towards the end of the TAF period with gusts exceeding 20 knots. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Cold Weather Advisory from 3 AM to 6 PM CST Monday for NDZ006- 007-014-015-024-026-054. MN...None. && $$ UPDATE...Perroux DISCUSSION...TT AVIATION...Perroux