


Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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670 FXUS63 KFSD 101145 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 645 AM CDT Thu Jul 10 2025 .KEY MESSAGES... - Periodic storm chances continue later today into Friday. Storms this evening will bring a threat of all storm modes, as well as locally heavy rain, mainly south of Highway 18. Less organized storms Friday bring primarily an isolated hail/wind threat. - A dry weekend is expected, with cooler temperatures Saturday warming above normal by Sunday and Monday. - The next risk for thunderstorms returns to the region late Monday into Tuesday. A few stronger storms are possible, but details are uncertain. && .DISCUSSION... Issued at 325 AM CDT Thu Jul 10 2025 TODAY-TONIGHT: Ongoing line of sub-severe convection is in the process of exiting our eastern counties, though more stratiform rain and isolated embedded thunder will linger for a bit longer. Trailing MCV near Brookings as of 3 AM will likewise slide east, and subsidence in the wake of this wave should keep our area mostly dry through midday. By this afternoon, will have to monitor location of diffuse boundaries lingering in the wake of this morning`s convection, as these may serve to focus better chances for development late afternoon into this evening as a wave lifts northeast out of western Nebraska. While there are some differences among the high-res models, also see a broad consensus showing a line of weak elevated storms near I-90 early- mid afternoon in response to weak warm advection. The greater potential for strong to severe storms looks to be near and south of Highway 20 corridor by late afternoon as the elongated wave lifts northeast. Steep mid-level lapse rates and a moist boundary layer will contribute to abundant instability (MLCAPE 2500+ J/kg) above a weak capping inversion. Overall mid-level winds are on the weaker side, but may be locally enhanced by the approaching wave which would lead to pockets of stronger deep layer shear supportive of organized storms capable of large hail up to golf ball size (maybe larger if a storm begins rotating) and isolated damaging winds of 60-70 MPH. If storms find a weak boundary with which to interact, a brief tornado is also possible. The weak mid level flow will initially lead to relatively slow storm motions which could promote pockets of heavy rainfall. However, storms are expected to evolve into a southeastward moving progressive line by late evening as the clusters become cold-pool dominant. This should confine the greater threat of severe storms and heavy rain to the first half of the night with activity in our area waning after 04Z-06Z. FRIDAY-FRIDAY NIGHT: Again it seems like a relatively quiet morning will give way to a slightly more active afternoon-early evening, the latter in response to 2 distinct features. First, the mid-upper level trough shifts slightly east with another piece of energy (perhaps a residual MCV) swinging toward northwest Iowa in the afternoon. Farther to the west, a deeper northern stream trough and associated cold front begin to push into the eastern Dakotas. Each of these features looks to have decent instability, though shear is much weaker than the preceding couple of nights so likely looking at more disorganized multi-cell clusters capable of marginal large hail/wind. SATURDAY-EARLY MONDAY: The northern stream trough brings a brief shot of cooler air into the northern Plains Saturday leading to highs in the mid 70s to mid 80s. This trough quickly erodes as a more zonal flow develops across the northern CONUS and warmer temperatures build back into the western Plains, and we will likely start next week with above normal temperatures back into the 80s and 90s (warmest west of I-29). Rain chances this weekend and into early Monday are low. LATER MONDAY-WEDNESDAY: A strengthening trough over the Rockies and High Plains develops Monday, lifting northeast into the Upper Midwest on Tuesday. This should bring our next chance for showers and storms, and overall it looks like a low potential for severe storms with weak shear across the area. However, ML output does hint a low severe probabilities, especially by Tuesday, so will be a period to monitor over the coming days. The trough looks to be followed by a more persistent stretch of cooler weather with some lingering rain chances into the middle of next week. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 643 AM CDT Thu Jul 10 2025 After a quiet start to the day, additional showers/storms are again possible after 22Z this afternoon and into this evening. Confidence is growing that storms will primarily be south of I-90, and especially south of Highway 18, including the KSUX area in the late afternoon/evening. Storms could contain strong/isolated damaging winds and potentially large hail. This activity should exit off to the southeast after 11/06Z, with a potential for MVFR ceilings developing in its wake. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...JH AVIATION...JH