textproduct: Aberdeen

KEY MESSAGES

- Front stalls across central and eastern South Dakota today. Cool to the north, but still mild and dry in central South Dakota with High/Very High Grassland Fire Danger and a Red Flag Warning this afternoon.

- Isolated strong storms possible this afternoon. Marginal Risk (level 1 of 5) for severe weather across central/north central and northeast South Dakota. Large hail and strong winds are the main threat. Slight risk (2 of 5) extends just into far eastern South Dakota through central Minnesota with hail 1 to 2 inches in diameter, high winds and low tornado threat. - Strong cold front will bring colder air back into the region Friday/Saturday, with temperatures 10 to 15 degrees below normal.

DISCUSSION

Issued at 110 AM CDT Mon Apr 13 2026

Stratus continues to advect into the region behind a cold front which will stall over central and eastern South Dakota today, setting up a temperature gradient from north to south. CAMS also indicate some fog on the cold side of this boundary, especially for locations that would experience an upslope with northeast winds. There is also a weak wave, a ridge rider, moving up across the area this morning. Its helping generate some elevated showers which will propagate across the CWA this morning.

Focus for today is fire weather and convection. With regards to fire weather...no changes to NBM temps/dewpoints today, which puts south central South Dakota well below 20% humidity. HREF probability of exceeding gusts of 25mph is nil though 2pm, increasing and expanding slowly thereafter up across central South Dakota, topping out at 40 to 70% in the warned counties. Getting about the same results looking at NAM BUFKIT soundings (mixed winds about 20kts), and as such winds are somewhat marginal. Then there is the wrinkle of potential elevated convection in the west, with NAM BUFKIT profiles indicating deep enough mixing to support high based convection. The warm front will have started lifting northeast in western/central South Dakota with ample sunshine. About half the CAMS show some weak convection across the western portions of central/north central South Dakota for a few hours in the afternoon. The convective mo from the sounding supports 'dry' thunderstorms with instability above the 0C level and thus a dry microburst risk. Thats associated with a shortwave that moves across northwest South Dakota later today. Theres still the departing wave and near neutral flow aloft in the eastern CWA this afternoon. Storms in the east would have to develop along the stalled front. Major wrinkle here is the stabilizing impact of stratus. NAM/GFS both keep the 950-875mb layer nearly saturated, with BUFKIT profiles in that area supporting a stable boundary layer north of the boundary. NAM/HRRR indicate the best instability has shifted down towards Sioux Falls area. Still the CAMS try to generate convection close to the Highway 14 corridor on the stable side of the boundary. This is in area with a slightly curved hodograph with strong unidirectional flow above 2km. Main concern down that way is storms with supercell type structure with a hail risk before everything passes east into Minnesota.

Significant surge in mild air for Thursday, with NAEFS 850mb temperatures a standard deviation above climo, dropping to a standard deviation below climo 00-12Z Saturday. ECMWF actually has 850mb temperatures down as low as -10C, which would be 5C colder in comparison to the NAEFS mean.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 110 AM CDT Mon Apr 13 2026

Terminals KABR,KATY,KPIR,KMBG

MVFR ceilings are nearing from ND, with MVFR to IFR ceilings forecast at ABR/ATY/MBG by 07Z to continue through at least 20Z (and much of the next 24 hours at ABR/MBG). There is a 20 percent chance of light showers early this morning, but coverage was not enough to include in a prob30 at this point. Fog has already developed over portions of the Prairie Coteau of northeastern SD, and develop over ATY 07-16Z today. IFR to LIFR visibility is forecast 09-15Z.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning from 1 PM CDT /noon MDT/ this afternoon to 8 PM CDT /7 PM MDT/ this evening for SDZ033-045-048. MN...None.