


Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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755 FXUS63 KFSD 120823 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 323 AM CDT Sat Jul 12 2025 .KEY MESSAGES... - Dry with below normal temperatures for today. Wildfire smoke moves into the region today into this evening, and this could reduce visibility and air quality - primarily over the eastern portions of the CWA. - Heat and humidity build back in for Sunday through Tuesday. Cooler temperatures return for the middle and end of next week. - A low thunderstorm risk for Sunday afternoon, then a higher threat for Tuesday and Tuesday night - with some threat of severe storms possible during that period. && .DISCUSSION... Issued at 317 AM CDT Sat Jul 12 2025 A gorgeous day ahead as surface high pressure builds into the region. An 850 mb thermal trough (teens C) slides eastward over the region through the day, and this will mix out to highs in the upper 70s to mid 80s. In addition to the relatively mild temperatures, dew points mainly in the 50s will result in an even more comfortable day. The only downside to the day will be the likelihood of Canadian wildfire smoke drifting into the region, with both the HRRR and RAP indicating that some of this may reach the surface over the eastern portions of the CWA by afternoon and evening. Even so, the current Air Quality forecast would indicate AQ remaining in the moderate range (level 2 out of 6), so while this will not impact most individuals those sensitive to smoke should take precautions. By tonight the low level flow begins to transition to southerly as the surface ridge shifts into the central Mississippi Valley, though it will still be a rather pleasant night with lows in the upper 50s to lower 60s. A return to much warmer temperatures by Sunday and Monday with rising upper level heights and a strengthening southerly low level flow. This will push temperatures back to above normal levels both days, with highs in the mid 80s to mid 90s. In addition, it will become increasingly humid as dew points climb back into the 60s to lower 70s. A surface trough will slide across the area on Sunday afternoon and evening, and a few of the hi-res models suggest isolated thunderstorms developing generally from the Interstate 29 corridor and eastward. Do feel that anything will remain very isolated with the better upper level support remaining to the north of our area. Although there will be instability present (MLCAPE 2000- 2500 J/KG), bulk shear is only around 25 kts with mid level lapse rates only around 5-6 C/KM, so the severe threat will be low. Latest guidance would suggest that Monday into Monday night will remain primarily dry with convection focused to our north in the vicinity of a stalled frontal boundary draped across northern SD into central MN. This begins to change by Tuesday afternoon and Tuesday night as the frontal boundary finally drops southward into our area and a series of upper level shortwaves move through the region. Although a little early for specifics, have to keep in mind the potential for at least some severe threat with plenty of instability in place - although bulk shear appears to be on the lower side at this point. That could change over the next few days so will bear watching. Of note, as mentioned in the previous discussion, machine learning guidance continues to indicate a 10-15% probability of severe weather in our area during that period. Behind this system, below normal temperatures work back into the area for the mid and end of next week with highs in the 70s to near 80 and lows in the 50s to lower 60s. Precipitation chances through this period will be focused more so on Wednesday into early Thursday as an upper level trough swings through the region, then trending drier for the end of next week. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1038 PM CDT Fri Jul 11 2025 Showers and storms continue to push east through northern IA, with an additional area of showers across south central SD into northern NE and storms in central NE. Although could see isolated showers for KHON and KFSD, confidence is low enough to preclude mention at this time. Still seeing MVFR visibility tonight with wildfire smoke behind the cold front. Reductions in visibility should be brief - a couple of hours at any one location. Northwesterly winds have been gusting around 25 knots for a couple hours behind the front as well. Wildfire smoke aloft and at the surface moves back in for most of the day Saturday, with latest guidance this evening a bit quicker and further east with the thickest smoke - now moving in by early afternoon and staying mainly east of the James River. Thus have gone a bit more pessimistic at KFSD reducing visibility to MVFR for a longer portion of the day. Conditions should improve slowly through the latter portions of the forecast period. Outside of smoke, northwesterly winds gust around 15 to 20 knots prevail through the day. Winds become light and variable Saturday night. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...JM AVIATION...SG