Area Forecast Discussion

KEY MESSAGES

- Strong west to northwesterly winds will increase behind a cold front this afternoon and continue through the overnight hours. Wind gusts will range between 30 to 55 mph, with the highest gusts across north central SD (Wind Advisory remains in effect) and along the eastern slopes of the Sisseton Hills through Tuesday morning.

- Dry conditions expected for Tuesday before weak disturbances are forecast to track over the region Wednesday through the weekend bringing the opportunity for occasional showers and thunderstorms.

UPDATE

Issued at 1227 AM CDT Tue Sep 15 2026

See below for an aviation forecast discussion for the 06Z TAFs.

UPDATE Issued at 832 PM CDT Mon Sep 14 2026

Low clouds have cleared out pretty much on schedule across the eastern CWA, leaving behind mostly clear skies. Will be watching winds during the overnight hours as they are expected to increase across north central SD. No sites have reached wind advisory criteria yet, but winds really aren't expected to increase until closer to 06Z. No changes to current headlines at this time.

UPDATE Issued at 630 PM CDT Mon Sep 14 2026

Aviation discussion updated below for the 00Z TAFs.

DISCUSSION

Issued at 220 PM CDT Mon Sep 14 2026

As of 19Z, the center of the stacked low pressure system is over northwestern ND/MT/Canadian border with the occluded/cold front extending southward through central SD (right along the Mo River) with winds west of the Mo River out of the west behind it. Temps range in the upper 50s and 60s with dewpoints in the 60s. So far, rain amounts at the office have been just below an inch for the day. Radar continues to show scattered showers and weak thunderstorms continuing east of the James River with an area of light showers or drizzle over portions of north central SD. Low stratus clouds continue (IFR/MVFR) with ceilings from 900-1500ft. As the front continues to track eastward, the last of the precip will exit eastern SD/MN by 00Z with skies clearing west to east across the CWA.

Through the evening, the low continues to deepen (to ~991mb) as it tracks northeast into Canada with a secondary cold front/trough tracking northwest to southeast over the CWA on the backside of the low tonight through the overnight hours. As the low deepens and pressure gradient tightens, the northeast to southwest jet streak circling around the southern/backside side of the low over the Northern Plains increases with winds at 500mb around 60-80kts, 850mb winds 35-55kts, and 925mb winds 30-45kts. 6hr pressure rises by 00Z per GFS is about +2 to +5mb over central SD, with these values spreading eastward across the CWA by 06Z. We really see an increase in pressure rises (up to +9mb, highest central SD) 06-12Z Tuesday as high pressure begins to filter in. This coincides with strong CAA moving in, especially with secondary trough, as models indicate 850mb temps go from +14 to +16C at 00Z to +6 to +10 by 12Z and 925mb temps from +19 to +23C to +10 to +13C. So a drop in 6-9 degrees drop in 12 hours! So pressure rises/steeper/gradients and CAA are ingredients for stronger winds at the surface. However, RAP soundings do indicate a shallow inversion developing this evening but seems to erode a bit with the colder/drier air moving in overnight, especially over the northern portions of SD. A stronger inversion does remain over south central and farther east you go into the CWA. This should allow for ongoing mixing to occur towards the surface.

So just behind the front, surface gusts this afternoon and evening will be highest over central SD, particularly north central SD with gusts of 30 to 55 mph. There may be a brief lull/decrease in winds late this evening before the secondary boundary passes across the CWA. Therefore, the combination of the increasing winds aloft, stronger pressure rises, and CAA will steepen the lapse rates with gusts between 25-45 mph, highest over northern and northeastern SD through Tuesday morning. Probability of NBM wind gusts>45mph is 40- 70% over north central SD (highest Corson/Dewey to the Leola Hills) with a 30-50% chance along the eastern slopes of the Coteau. 24 hour max wind gust potential ranges from 40-60 mph, highest north central SD. HREF probability of gusts at or over 45 mph is upwards of 40-70% over north central SD and higher than NBM for Coteau ranging from 50- 75%. So blended NBM/NBM90 for winds downslope of the Coteau to represent this potential higher gusts. So the Wind Advisory across north central SD remains in effect through the overnight. If we end up getting more widespread wind advisory winds, then it will need to be expanded eastward. Also was hesitant on issuing a Wind Advisory for the Coteau with a lack of southwest component and the deeper inversion. This will also need to be monitored with the next shifts. As mentioned, if we develop a stronger and/or larger inversion (or less CAA) then the gustier winds will not mix down as effectively to the surface.

By Tuesday, the low/trough aloft will be northeast of the CWA with zonal flow as high pressure filters into the region with overall dry weather expected. As the high moves in, pressure gradients relax and the gustier winds aloft with the low move out of the area. Therefore, winds will decrease through Tuesday. Zonal to southwest flow continues Wednesday through the end of the week as a cutoff low aloft and its trough hovers over the western CONUS (low weakens into an open wave by Friday) with a ridge and mid level high strengthening over the central and southeastern US. Within this zonal to southwest flow in an active -PNA pattern, weak shortwaves will pass over the region Wednesday through the weekend bringing occasional chances of showers and thunderstorms with the best chance (50-80%) being late Thursday and Friday. Temperatures will overall be about normal ranging in upper 60s and 70s across the CWA through the week.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1227 AM CDT Tue Sep 15 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast throughout the TAF valid period. Low-level wind shear (LLWS) potential may exist, mainly at KATY during the first few hours of the TAF valid period.

ABR WATCHES / WARNINGS / ADVISORIES

SD...Wind Advisory until 1 AM MDT Tuesday for SDZ003-015. Wind Advisory until 4 AM CDT early this morning for SDZ004-005- 009-010. MN...None.