textproduct: Aberdeen

KEY MESSAGES

- Areas of dense fog across northeast/north central this morning.

- Isolated weak thunderstorms this morning.

- Warm, dry, and windy later today with record/near record highs and critical fire weather conditions for portions of central/south central SD.

- Strong storms possible Monday afternoon. Slight Risk (level 2 of 5) for severe weather along and east of the Interstate 29 corridor.

DISCUSSION

Issued at 1245 AM CDT Sun Apr 12 2026

Isolated thunderstorms northwest of Aberdeen this morning associated with a southwest flow shortwave to our northwest. Profiles indicate a deep dry subcloud layer, with 850mb temperatures reaching their peak during the morning. NAM BUFKIT profiles indicate as much as 20C dewpoint depressions where 850mb temperatures are close to +20C. Thus, will include a 20-30% chance for thunder and watch for isolated strong wind gusts.

Wrap around dry air this morning, helping to scour out remnant low level moisture, however some higher mid level dewpoint air pivots back around out of North Dakota. This sets up a gradient across the CWA from north to south of higher to lower dewpoints respectively. The main question is how low will these get, especially in areas highlighted for Red Flag conditions. Otherwise we're pretty confident in winds achieving criteria as NAM BUFKIT profiles continue to indicate deep mixing (up to 8-9kft) and mixed down winds of 20-30kts. They actually start out the day stronger, but the gradient weakens after 18Z as the low moves into northwest Minnesota, especially out in central SD. As for temperatures, deterministic NBM is still down around the 10th percentile, with the 25th-75th range down to around 3-4F suggesting a high confidence forecast which really has us questioning why deterministic values are so low in comparison. Current temperatures around 60F means it won't take much to warm to NBM deterministic. Will continue to use the NBM mean given favorable mixing winds/ample sunshine and a lack of additional mitigating factors.

Zonal flow aloft with a southwest flow shortwave ridge keeps us clear of precipitation through Monday morning. A weak mid-level trough comes into the northwestern part of the state late Monday. There is a warm sector with 850mb temperatures up to +18C over southeast South Dakota Monday morning, and that warm front weakens then reforms as the wave comes in later in the day. Cant rule out elevated convection with the first surge, but the second responds more as the trough approaches from the west and that is what CAMS are picking up on. Profiles suggest strong unidirectional flow above an inversions with stable near surface flow out of the east northeast for Watertown, though with more curved hodographs down towards Brookings. NAM has the best CAPE well southeast of the CWA, HREF puts the favorable area around highway 14 in eastern South Dakota.

That shortwave heads out Tuesday morning. The next mid level wave of note comes out of the Colorado Rockies region and pushes east northeast into southeast South Dakota and Nebraska. Likewise, the surface low also travels mainly to our south. Up this way, a weak surface high ridge extends southwards out of Canada into the Dakotas. This results in a brief mid-week cool down. Another surge of mild air follows, with the core of the mildest air moving through Thursday. A much cooler airmass follows for Friday/Saturday. Temperatures late in the forecast drop to about 10 to 20F below normal.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1245 AM CDT Sun Apr 12 2026

Terminals KABR,KATY,KPIR,KMBG

Low level wind shear with winds just above the surface at 35-45kts will continue for another 2-4 hours. Warm air advection nocturnal showers and a couple of thunderstorms reside west of ABR. Have added -tsra temporarily at ABR, although they may end up staying just north of the airport. MVFR fog will be a concern initially at ATY. Otherwise, winds will increase and gust 25-30kts from mid morning through the daytime hours.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Dense Fog Advisory until 7 AM CDT this morning for SDZ004-005- 007-008-011. Red Flag Warning from noon CDT /11 AM MDT/ today to 7 PM CDT /6 PM MDT/ this evening for SDZ033-035-045-048-051. MN...Dense Fog Advisory until 7 AM CDT this morning for MNZ039-046.