967 FXUS63 KFGF 120334 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1034 PM CDT Mon Sep 11 2023 .UPDATE... Issued at 1034 PM CDT Mon Sep 11 2023 Other than one lingering shower in our southeast most activity has ended, and most CU has dissipated with clear over a lot of our area (a few pockets of stratus). Upstream Tds are sill in the upper 30s and lower 40s, so there isn't a change in expected impacts from the last update. The main adjustments were to reflect near term trends. UPDATE Issued at 640 PM CDT Mon Sep 11 2023 What few showers are left are quickly weakening/falling apart with peak heating past and sunset approaching, leading to stabilizing BL conditions. Patchy ground fog remains possible in our far south where BL moisture may be just deep enough, while lower Td arrive where that main surface ridge is projected to build south later tonight/Tuesday morning. Clearing skies (outside of areas of stratus) are already occuring as CU breaks up with decoupling at sunset, but we should see good radiational conditions in our north. Upstream surface Tds are in the upper 30s though where the ridge center is moving out of Manitoba, lowering confidence in a frost threat (requiring 36F or less 6ft temps). Still, RAP BL Tds do drop to around 35 after 10Z, and if those drier Tds mix to the surface as the surface inversion steepens, a few spots may drop in the 33-36F range (mainly in Towner, Cavalier counties in ND and eastern Marshall, northwest Beltrami- bog areas of MN). Due to the marginal/highly localized nature of any frost potential, I am still opting not to go with a frost advisory. I would feel more confident in frost potential if lower Tds were observed upstream than what I am seeing. && .SHORT TERM...(This evening through Tuesday night) Issued at 313 PM CDT Mon Sep 11 2023 -Showers and a few thunderstorms pushing southeastward this evening. -Some stratus/fog possible in some areas overnight -Clearing in northern counties could drop temps close to frost point. Vorticity lobe on the backside of the upper trough continues to dig down out of Canada this afternoon, and will progress southeastwards into MN overnight. Cold front has pushed through most of the CWA, but scattered showers continue across many of the counties except the northwest. With 500 J/kg of ML CAPE in portions of southeastern ND and western MN, some thunder will continue to be possible for the next few hours. CAMs and larger scale models are in pretty good agreement on shower and isolated thunderstorm activity continuing to push southeastward through this afternoon and early evening. By midnight, think we should see the showers push fully out of our area. Tonight, there will be some subsidence and high pressure coming in behind the frontal boundary. However, several ensemble members show some lingering low level moisture, particularly across our southern and eastern counties. Think our eastern tier will stay pretty cloudy, as there are high probabilities for low clouds and even some fog over central ND that could drift westward. There are even some low probabilities for stratus and fog extending from southeastern into central ND along the edge of the surface high. Think at least there will be some cloud cover lingering overnight, which will have an impact on temperatures. While the south and east look to remain cloudy with dew points in the 40s, think there will be some drier air and clearing skies across our northern counties. Temps should drop down at portions of the northern Devils Lake basin and northern RRV, just a question of how much. NBM probabilities of less than 40 degrees in that area are between 40 and 70 percent. Confidence in 36 or less is lower, around 10 to 20 percent, although more recent runs have been bringing that value up a bit in portions of our far northwest. Given upstream dew points are still pretty high in the low 40s to upper 30s, leaned towards the middle of the ensemble pack with low temps around 37 to 38 in our northwest. Confidence in anything lower is not high enough to include a frost advisory at this point. Upper ridging between systems will nose into the Plains later Tuesday into Tuesday night, with the surface high shifting east. Temps should stay mainly in the 60s during the day on Tuesday even with some sunshine, but increasing southeasterly winds Tuesday night will keep our temps in the 40s with some upper 30s in northwestern MN. .LONG TERM...(Wednesday through Monday) Issued at 313 PM CDT Mon Sep 11 2023 Wednesday and Thursday...Upper ridging comes into the Plains for a brief period mid-week before another shortwave comes over the top of it into the Prairie provinces and Northern Plains on Thursday. Southerly winds will be ramping up on Wednesday as a surface trough gets going over the High Plains. This should help boost temps back into the 70s by Wednesday afternoon for areas along and west of the Red. A cold front will start pushing in late Thursday, but with warming ahead of the boundary some spots could still push 80 in the southern Red River Valley. Some showers and thunderstorms possible as the front pushes through, although moisture is not great and coverage looks somewhat scattered. Instability seems fairly limited with ensemble averages in the 100-500 J/kg range and even the bullish NAM mostly under 1000 J/kg. Severe weather threat is minimal. Blended solution gives 30 to 40 percent probs of any precip as the front moves through, which seems reasonable. Friday through Monday...Upper troughing digs into the Great Lakes for the end of the week and into the weekend. This will bring a bit of a cool down for the first part of the period, with temps rising back to above average values for the first part of next week. Other than a few isolated showers possible near Lake of the Woods with the cyclonic flow aloft for Fri/Sat, the period seems fairly dry. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 640 PM CDT Mon Sep 11 2023 Showers are quickly dissipating across eastern ND and northwest MN with the loss of peak daytime heating/approaching sunset. There is still a lingering stratus layer that may survive beyond sunset in north central MN towards KBJI that is shown by guidance to fill back in overnight with possible IFR by 12Z before eventually clearing later Tuesday morning. Other terminals are favored by guidance to remain VFR through the remaining TAF period, though there is a signal for possible fog and stratus formation in far southeast ND and west central MN that could result in temporary/brief aviation impacts at KFAR around 12Z (not favored but still possible and worth monitoring). && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...DJR SHORT TERM...JR LONG TERM...JR AVIATION...DJR