FXUS63 KFGF 260003 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 703 PM CDT Sun Aug 25 2024 .KEY MESSAGES... - Heat impacts are likely today, with a heat advisory out for all of the Red River Valley - There is a level 2 out of 5 (slight) risk of severe weather this evening and a 3 out of 5 (enhanced) risk into Monday. && .UPDATE... Issued at 702 PM CDT Sun Aug 25 2024 Regarding severe threat: Strong cap delayed initiation as per earlier trends and while there is some indication on mesoanalysis of weakening CIN immediately along the leading edge the cold front (already past Devils Lake), satellite trends continue to show less impressive/flatter CU and no indication of organized initiation. At this point elevated/less organized convection may remain favored with the sunsetting and the window closing. Latest HRRR/SSCRAM that initiated with these trends now has significantly backed off on earlier indications of organized/robust convection, now favoring elevated/weaker convection. High elevated instability is still present and the southern part of the trough in Canada has yet to pass (along with the cold front) which will be occuring through the late evening/overnight. There is still a window through the night for an isolated severe threat, though confidence has decreased. Regarding heat impacts: Clouds delayed heating, but we still ended up with widespread heat index values 100-108 (highest in the southern Red River Valley) and while the cold front is pushing in from the west and the sun is setting. Current advisory continues through 8PM, but impacts may last a little longer for a few locations (9PM) due to the extreme nature of the Tds ahead of the front (75-79F common). As top of the hour trends for most locations are supporting allowing it to expire at 8PM. && .DISCUSSION... Issued at 220 PM CDT Sun Aug 25 2024 ...Synopsis... Satellite imagery shows low clouds still lingering over the area. The ridge's dominance is on the downturn right now, with a trough progged to come through behind it in the beginning of the work week. Another brief period of ridging mid-week, followed by another trough to end the work week. The second trough will occur into Thursday morning, bringing more precipitation, but guidance is a bit murky on how much and if there could be severe weather with it right now. ...Heat Impacts Today... Today will feature unusually high dewpoints in the Red River Valley, thanks to robust Gulf of Mexico moisture advection. When you combine this with high temperatures in the 90s due to the ridge, heat indices are expected to get into the low 100s Sunday afternoon. Guidance has changed its tune again, proving yesterday's run to be more of an anomaly. There is now a 40 - 60% chance of warning type temperatures (105 or higher), so we have decided to keep the heat advisory and let it ride. Regardless of the products out, it will be a hot one this afternoon, especially in areas that see more sunshine. If you have plans to be outside, make sure you're staying hydrated and taking frequent breaks in the shade or the AC to cool off. ...Severe Potential Sun/Mon... As for the severe weather potential, lingering clouds are limiting daytime heating, making us question how much we will get and if it could be enough to break the cap. Even though we are close in time to the event, there is still uncertainty among the guidance on whether storms will even fire or not. Forecast soundings show the presence of a cap, preventing parcels at the surface from accessing the instability above except mainly along the front (the primary forcing). With this, we expect storms to be mainly confined to the area along and immediately ahead of the front. Most likely storm mode will probably be clusters and embedded supercells, but there are plenty of models showcasing a typical QLCS linear storm mode. If storms can fire, main hazards include large hail, dangerous wind gusts, and a tornado or two possible. Into Monday, more shear could come into play, which could increase hail size and continue the tornado threat (currently, shear looks a bit marginal for tornado threat). Monday looks a bit more QLCS/bow echo storm mode, and more in our southern CWA (along HWY-10 and south). && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 702 PM CDT Sun Aug 25 2024 Earlier MVFR stratus is finally breaking up/lifting trending towards prevailing VFR while a cold front pushes east shifting winds to the northwest and eventually north later in the TAF period tonight and Monday. Shower/thunderstorm coverage and chances at TAF sites in eastern ND/northwest MN remain highly uncertain, and while a few showers/storms may still develop I was not confident enough to include in TAFs based on current trends. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Heat Advisory until 8 PM CDT this evening for NDZ008-016- 026>030-038-039-049-052>054. MN...Heat Advisory until 8 PM CDT this evening for MNZ001>005-007- 008-013>015-022-027-029-030-040. && $$ UPDATE...DJR DISCUSSION...AH AVIATION...DJR