276 FXUS63 KFSD 100941 CCA AFDFSD Area Forecast Discussion...CORRECTED National Weather Service Sioux Falls SD 441 AM CDT Tue Jun 10 2025 .KEY MESSAGES... - Slight visibility reductions along with minor air quality concerns from wildfire smoke into this morning, and possibly again late tonight into Wednesday morning. - Morning showers Wednesday give way to increased risks for thunderstorms south of I-90 Wednesday afternoon and evening. Marginal (Level 1 of 5) risk for severe weather with large hail and isolated strong wind gusts. - Unsettled pattern with periodic thunderstorm chances continues into the weekend. Only marginal confidence on exact timing and location, but isolated strong to severe storms and locally heavy rain are possible Thursday afternoon/night. - Temperatures rise through the upcoming weekend, bringing additional thunderstorm risks early next week. Monitor for strong storm potential Sunday-Monday. && .DISCUSSION... Issued at 430 AM CDT Tue Jun 10 2025 TODAY-WEDNESDAY MORNING: Building mid-upper level heights today will allow warmer air to expand into the region, with highs this afternoon in the mid 80s to mid 90s. Tonight a weak wave will slide atop the broad upper ridge, dragging a frontal boundary slowly southeast through the area. This boundary will become a focus for high-based showers and perhaps a few storms as we head through tonight and Wednesday morning. WEDNESDAY AFTERNOON-FRIDAY: The boundary continues to push south through Wednesday afternoon and should be a focus for late day thunderstorm development Wednesday. Unfortunately, still not seeing a lot of agreement on the placement of the surface front, though broad consensus looks to be between Highway 18 and 20 in northwest Iowa. As a broad wave arrives from the west, expect to see storms develop along to just north of the surface boundary in the late afternoon, tracking east through the evening. Forecast soundings show the antecedent air mass is still relatively dry in the mid levels, which could support corridors of stronger winds with cold-pool dominant storms. Isolated large hail is also possible, but displacement of the stronger instability south and stronger shear north of the boundary leaves a narrow corridor of support for organized hail-producing storms, perhaps as large as half dollars with the strongest storm cores. Later Wednesday night into Thursday evening could be a repeat of tonight. This would begin with development along the elevated warm front as it lifts back to the north and a weak low level jet impinges on the boundary into Thursday morning, followed by a potential for stronger convection Thursday afternoon/evening as another wave slides into the area. Models begin to show less and less agreement on placement of boundaries, which will ultimately depend on the previous day`s activity. This leads to waning confidence as we move forward in time. However, if there are boundaries in the area later Thursday, they should become the focus for late day development. Similar to Wednesday, stronger instability and shear are not coincident, so again would expect isolated strong to severe storms. One additional concern for later Thursday and especially Thursday night would be a potential for areas of heavy rainfall. Deepening moisture profiles and warm cloud depths will lead to efficient rainfall producing storms, and the main question will be whether successive rounds of showers and storms Wednesday into Thursday night will impact the same locations or be more transient. SATURDAY-MONDAY: Not a lot in the fine detail department to latch onto in this long range period. There is some model consensus that a broad upper ridge will become established from the Desert Southwest into the southern-central Plains early next week, and various shortwaves topping the ridge will bring periodic storm chances to the northern Plains. However, uncertainty in timing and location abounds given lack of model agreement in those finer details. That said, Sunday-Monday will be a period to monitor for severe weather risks if the storm track falls across our forecast area. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1039 PM CDT Mon Jun 9 2025 VFR conditions are expected for the TAF period. The last bit of VFR/MVFR stratus continues to push east late this evening across part of southwest Minnesota. Smoke remains across part of the area, mainly west of I-29 and north of I-90. Should see this smoke persist through the night before southwesterly winds pick up tomorrow morning. Good news is that only minor obstructions to visibility is expected in the smoke with visibilities only falling to about 6 miles at the worst. Winds will pick up out of the southwest tomorrow morning which should clear the area from any residual smoke. Marginally breezy winds are expected with gusts up to 15-25 knots tomorrow afternoon, strongest along the Buffalo Ridge. Winds will begin to turn northerly to end the TAF period as a cold front pushes into the area. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...JH AVIATION...Meyers