textproduct: Sioux Falls

KEY MESSAGES

- Warm, dry, and breezy conditions over the weekend will lead to elevated fire concerns, especially on Saturday. Make sure to limit any activities that could create a spark!

- Both high and low temperatures on Saturday will approach record territory.

- A return to an active pattern by next week will lead to multiple rain chances (30%-70%) throughout the week, highest on Wednesday and Thursday.

UPDATE

Issued at 153 AM CDT Fri Oct 9 2026

Focus for this past evening and so far early this morning has been on elevated storms which continue to develop and track to the east-southeast near an 850mb boundary, extending from far southeast South Dakota across northwest Iowa, mainly between U.S. Highway 18 and IA Highway 3. Multiple elevated supercells have tracked over or very near the same locations, especially portions of Clay/Union/southern Lincoln counties in SD, and Sioux/Plymouth/Cherokee counties in IA. Some locations may have seen multiple rounds of hail, though in most cases, the tracks of storm cores were just slightly displaced from previous rounds.

Models indicate this activity should begin winding down over the next 1-3 hours as the axis of the low level jet impinging on the above-mentioned boundary slowly shifts east, along with a subtle mid-level wave which is likely aiding in development.

Once this activity shifts east of the area prior to daybreak, focus will then shift toward warmer and windier conditions which develop into this weekend. Given the persistent storm activity, did not have much time to examine the latest models or make many significant adjustments to the forecast. However, given recent trends on well-mixed days, did favor highs closer to the 90th percentile of the NBM for Saturday, while similarly nudging dew points downward toward the HRRR/RAP. This continues to produce a broad area of High Grassland Fire Danger across southeast SD and southwest MN, and will have to monitor trends for possible fire weather headlines as RH does drop below 25 percent in some areas with winds gusting over 30-35 mph.

DISCUSSION

Issued at 152 PM CDT Thu Oct 8 2026

Dry conditions beneath partly cloudy skies continue this afternoon. The dry conditions look to persist for the rest of the afternoon and into the evening hours before chances for showers and storms return to the forecast area. A weak mid level shortwave trough will push into the forecast area, strengthening the low level jet (LLJ) and low level warm air advection (WAA). The LLJ and WAA will steepen mid level lapse rates, resulting in sufficient buoyancy between 700 to 1,200 J/kg of CAPE. Thus, thunderstorms are expected on the nose of the LLJ. Effective shear values will be sufficient at 35 to 40 knots. The lingering uncertainty is where storms will develop. Latest guidance has come in with a further east solution. Should this solution pan out, then little to no storms would develop in the forecast area. Think the most likely scenario is that the broad WAA in place will develop a few storms in the CWA, mainly in northwest Iowa this evening and night. A few of these storms could be strong to severe with large hail up to the size of ping pong balls. Should see storms push east of the forecast area by 5 to 6 am.

Friday will see warming highs up to the 70s and 80s thanks to the previously mentioned WAA. Winds will also be strengthening throughout the day as low level pressure gradients tighten with southeasterly winds gusting to 20-30 mph. With the tighter pressure gradients in place, breezy winds will persist through the evening and night, this will keep low temperatures very mild, with lows only falling to the 60s overnight. These warm overnight lows will be near or may break warm low temperatures records.

The thermal ridge axis will remain parked over the Northern Plains on Saturday, resulting in the warmest temperatures over the weekend. High temperatures will warm to the 80s across the area with a few locations across central and south central South Dakota seeing highs potentially reach 90F. These warm high temperatures are near records currently. Could see temperatures creep towards record territory if highs continue to warm heading into Saturday. The heat will be accompanied by stronger southerly winds and lower humidity, yielding elevated fire danger across the area. The lowest humidity and hottest temperatures continues to look to reside over central and south central South Dakota where humidity values look to fall below 25%. However, winds will be weakening in this area through the daylight hours as the low level pressure gradient is shunted a bit eastward. Locations along and east of the James River will see the strongest winds with gusts up to 30-40 mph. Isolated higher gusts up to about 45 mph is possible along the Buffalo Ridge in southwest Minnesota. This will result in an offset of the strongest winds and lowest humidity. Fuels continue to remain green, though continue to slowly cure. That said, the offset of highest winds and lowest humidity along with the mainly green fuels will keep fire danger capped at high. Fire danger will come to an end Saturday evening as humidity increases. Winds will slowly weaken through the evening and overnight hours, continuing another night of mild low temperatures in the 60s. These low temperatures will again come close to record warm lows.

Warm temperatures will continue through Sunday though not as warm as a cold front begins to push into the forecast area from the northwest. Medium range guidance continues to vary on how quickly the front pushes through the forecast area. Winds will remain breezy but much weaker than Saturday's winds. Humidity will be lower, though above critical thresholds, so some elevated fire danger remains possible.

An upper level trough will dive across the west coast on Monday before beginning to eject into the Plains late Tuesday and Wednesday. There remains significant variance in the evolution of this wave but the ensembles show a clearer picture with the closed low transitioning to an open wave as it pushes into the Plains. This will also push the highest probabilities for rain to the middle of next week. The ensembles show a 30-70% chance for rainfall totals to exceed a tenth of an inch Wednesday through Thursday. In addition to the chances for rain, temperatures will trend to near seasonable with highs in the 60s and low sin the 40s and 50s.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 633 AM CDT Fri Oct 9 2026

VFR conditions are expected through this TAF period. Southeast winds will become a bit gusty this afternoon, generally 18-25kt with strongest winds west of U.S. Highway 81.

Gusts ease at sunset, but may increase again late evening to overnight as a low level jet develops over the region. This will also lead to low level wind shear, with southwesterly winds in excess of 35-40kt as low as 1000ft AGL atop a much lighter south-southeast surface flow.

FSD WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None. IA...None. NE...None.