


Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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560 FXUS63 KFSD 280652 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 152 AM CDT Sat Jun 28 2025 .KEY MESSAGES... - Hot and humid day expected throughout the region. Heat index values may reach the 100 degree mark, and anyone spending time outdoors should take extra caution to prevent heat illness. - Isolated to scattered strong to severe thunderstorms again possible late Saturday afternoon into early Sunday morning. Storm risks begin after 4-5pm, bringing brief 2.0" hail risks, but larger potential for 70 mph downburst winds. - Storm risks continue into Sunday, though potential remains highly murky and depends on storm development Saturday evening/night. - Near to above normal temperatures for much of the upcoming week, with storm risks returning by the middle of the week. && .DISCUSSION... Issued at 150 AM CDT Sat Jun 28 2025 THIS MORNING: Cluster of strong thunderstorms persist across areas east of I-29 as of 2am. These storms remained tied to a weak lobe of vorticity moving through the region, and will continue to move east through daybreak. With the increase in the LLJ some isolated stronger cells remain possible in the southwestern periphery of this weakening MCS. Additional scattered thunderstorms may develop over the northern half of South Dakota on the nose of the low lvl jet through daybreak. Well to the north over eastern North Dakota and western Minnesota, a second developing MCS may track east southeast into Saturday morning. While this convection won`t impact the Tri- State area, it will lay out an outflow boundary over central MN into Northern South Dakota. TODAY: Lingering morning scattered showers and thunderstorms north of Highway 14 will gradually dissipate by mid-morning. By mid-day we`ll have a better idea where two primary features will fall. One being an west to east running outflow boundary over central MN into northeastern South Dakota, and second area will be a trailing cold front potentially stretching from Valentine to Huron and Watertown by early afternoon. South and east of these features, a very warm and humid day is likely. Given increase in moisture have lowered highs slightly and bumped dew points up a bit. This results in heat index values approaching the 100 degree mark by mid-afternoon. At this time, will hold off on a heat advisory, but if morning trends show higher temperatures/dew points an advisory could be issued. Instability is expected to grow substantially through the day, with MLCAPE approaching 3000-4000 J/KG through most of the warm sector. The biggest question that models continue to struggle with is the degree of inhibition and resolving the weak and subtle shortwaves that could help spur development along the residual outflow and fronts after 4-5pm. The most favored area for development will be through central Minnesota and northeastern South Dakota where synoptic forcing and mid-lvl winds will be stronger. Development southeast on the cold front into central SD is more conditional. Given the pool of instability, any storm that develops will become strong to severe quickly. However we`ll remain on the southern periphery of stronger mid-lvl winds, leaving effective shear on the lower end. Most of the area on the cold front could see multi- cellular development, with better supercell chances (and accompanying very large hail/wind/tornado potential) form along the outflow to our north into Minnesota. Much like Friday evening, initial storms may have 1.5-2" hail, before shifting towards 70+ mph downburst winds. Cold pool development could push a cluster or two of storms southeast into the evening and early overnight hours. SATURDAY NIGHT: Models remain largely split on a secondary wave crossing the Rockies overnight and developing some sort of MCS over the Dakotas. Should this develop an attendant wind risk could persist through daybreak Sunday. SUNDAY: Confidence remains lower than normal into Sunday given all the scattered convection risks up to this point. A belt of stronger mid-lvl winds enters the Northern Plains early Sunday, with increasing troughing pushing the cold front southeast during the day. It`s not impossible to have some convection remaining through Sunday morning and any MCS that crosses the state could push the effective front further southeast through the CWA. However if no overnight convection forms, then areas along and east of the passing front remain in a good position for scattered development early in the afternoon Sunday. This activity may again produce hail/wind risks. MONDAY-FRIDAY: High pressure moves into the Plains early next week, pulling temperatures down slightly, but keeping conditions dry through Tuesday. Some signals for modest mid-lvl moisture return and warm advection into Wednesday morning, owing to an increase in PoPs. Mid-lvl heights try to build for the second half of the week, and that would likely push high temperatures back towards the 90s for the 4th of July holiday. Convection chances remain highly uncertain for the holiday. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1213 AM CDT Sat Jun 28 2025 Scattered convection continues to move through eastern South Dakota early this morning. Within thunderstorms, drops to MVFR/IFR visibility is possible, with CIGs near 3k ft AGL. Into mid-morning, the greatest convection risks will continue near or north of Highway 14, with skies clearing further south. A frontal boundary sets up over eastern South Dakota, with isolated to scattered convection forming along this boundary after 4-5pm. Highly uncertain on the eventual track of this convection into the evening, so will continue to remain with PROB30 groups at all TAF locations. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...Dux AVIATION...Dux