994 FXUS63 KFGF 210010 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 710 PM CDT Fri Aug 20 2021 .UPDATE... Issued at 710 PM CDT Fri Aug 20 2021 A possible sting jet associated with strong closed mid-upper low, combined with region of strong subsidence and increasing pressure gradient is resulting in wind gusts as high as 60 mph based on reports west of the RRV and the southern Devils Lake Basin. These winds are not associated with the thunderstorm activity, but could still cause impacts through the evening hours as this upper low transitions northward. I issued a High Wind Warning to cover this threat through 06Z (1 AM) tonight, though conditions may improve earlier. && .MESOSCALE DISCUSSION... Issued at 636 PM CDT Fri Aug 20 2021 A transition to more of a damaging wind threat appears to be going on, with the potential remaining for tornadoes and hail. There still exists an instability axis across Minnesota, leaking into northwest Minnesota, and meaningful shear still exists. While it may appear threats are dwindling, the severe threat remains. Surface analysis indicates the primary low pressure is centered over east-central North Dakota where a triple point appears to exist. Circulations have been noted on the storm near the triple point. Looking at satellite, drier air has begun to filter into the area from the southwest, crossing into Minnesota. The instability axis appears to be centered over Minnesota, with modest MLCAPE values still remaining in the 1000+ J/kg. Effective bulk shear still exists in association with the low, with 30-40 knots remaining primarily on the North Dakota side, in association with the low. As the cold front pushes eastward, the expectation is for this shear to push more into Minnesota. In tandem with the 850mb jet over Minnesota, convection appears like it will sustain in that area, and potentially have more development along the pushing cold front. The primary threats from these storms will more likely than not be damaging wind gusts, although a tornado cannot be ruled out, especially if 0-3km bulk shear vectors prove favorable within the surge. Regarding bulk shear vectors, 0-3km shear vectors primarily will continue to push from the southwest. Should there be any surges, they could align well within the parameters for QLCS tornadoes. These will be the primary two areas to look for for tornadoes. On the hail front, hail still remains a potential issue over the next few hours, although given thermal profiles there remains a rather low ceiling for sizes. The general expectation over the next few hours is for these multicell clusters to continue through the area, with a few transient circulations possible on the more discrete clusters. Attention will turn to Minnesota over the next few hours as the cold front continues to push eastward, although uncertainty exists in how the evolution of the later hours will go thanks to drier air advecting into the area. && .SHORT TERM...(This evening through Saturday night) Issued at 332 PM CDT Fri Aug 20 2021 Convection strength and type remain the main challenges for the period. Main upper trough is still out around the Montana border, but the surface low has developed just west of our counties and there seems to be a weak secondary low developing over southeastern ND. Plenty of ML CAPE over 1500 J/kg extending all the way up towards the international border in northwestern MN, with deep layer bulk shear around 35 to 40 kts. Storms have formed in a line along a weak lead shortwave and warm air advection across our far eastern tier of counties, with more discrete cells developing behind it along the southern Red River and Sheyenne Valleys ahead of the main surface low center. CAMs continue to show signs of some congealing into a somewhat broken line as the surface low lifts northeast late this afternoon and evening. This seems reasonable given increasing forcing as the main trough ejects eastward and the cold front pushes into our area. As the convective activity pushes northeastward this afternoon and evening, there should be a dry slot making its way into portions of our counties. There is good agreement with the short range ensembles for some deformation zone showers mainly in our northwestern counties. These showers will continue in our north through the overnight hours and even along the international border into Saturday, long past the point where convection has moved out of our area. Breezy northwest winds and cold air advection for the rest of the region tomorrow, with much cooler highs in the 60s to low 70s and drier air behind the surface low. Temps Saturday night will be fairly cool, down into the 40s and low 50s with winds shifting back to the southeast. .LONG TERM...(Sunday through Friday) Issued at 332 PM CDT Fri Aug 20 2021 A few chances for storms and rain will be possible across the long term as a cooler and more active weather pattern persists. The first opportunity comes on Sun with the next chance arriving on Tue. The underlying conditions across the long term are expected to favor cooler, below normal temperatures. This is supported by 850 hPa temperatures generally in the teens and low relative H5 heights as well. The main question mark for Sun will be the magnitude of return flow into the area. Current forecasted highs in the upper 60s to mid 70s are anticipated with forecasted dewpoint temperatures recovering into the low 60s. A resultant narrow corridor of instability in conjunction with ample shear may be supportive of a few strong thunderstorms Sun aftn into the eve. Rainfall totals, as a result, will vary spatially and be locally higher with any thunderstorms that may develop. Current ensemble guidance is indicating a 70 to 80% chance for rainfall accumulations greater than or equal to 0.1" across eastern North Dakota and into northwestern Minnesota. The active weather pattern is likely to persist into the week ahead. Southwesterly flow aloft will continue to steer any embedded shortwave systems in the general direction of the northern Plains as a result. The next prospective shortwave and attendant rainfall chance is then progged to arrive on Tue. This looks to be a much weaker wave with less upper level support and moisture return as the Sun system. Thus, impacts look to be on the lower end at this time, but will continue to monitor this system moving forward. Otherwise, cool, below normal high temperatures in the 60s to 70s are expected to be a mainstay throughout the remainder of the long term period. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 636 PM CDT Fri Aug 20 2021 Clusters of showers and thunderstorms have transitioned over northeast ND, west central and northwest MN. There is a clearing trend in southeast ND and trends should be fore activity to end this evening from the southwest to northeast, though a few showers or weaker thunderstorms may linger in the Devils Lake Basin later into the night. Brief IFR conditions are possible with thunderstorm activity, along with erratic stronger winds. Severe potential is lingering for a few more hours with thunderstorm activity. Several areas of MVFR stratus will continue to fill in and persist through the remaining TAF period across eastern ND and northwest MN. Surface low pressure and several frontal passages are going to result in shifting winds from the southeast to the west-northwest and occasional gusts 20-35 kt. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...High Wind Warning until 1 AM CDT Saturday for NDZ006>008-014>016- 024-026>029-038-054. MN...None. $$ UPDATE...DJR MESOSCALE...Perroux SHORT TERM...JR LONG TERM...WJB AVIATION...DJR