textproduct: Aberdeen

KEY MESSAGES

- There is a Marginal (level 1 of 5) Risk for isolated to scattered (20-30% chance) severe storms to develop in north central SD this afternoon and move east this evening. The primary threats will be 1 inch hail and 60 to 70 mph wind gusts. These storms are most likely to be limited to the highway 12 corridor and locations north.

- Increasing temperatures today, with peak heat for the weekend. Temperatures Saturday/Sunday 10 to 20 degrees above normal (upper 90s to low/mid 100s). Less intense, but still above average heat for next week.

UPDATE

Issued at 623 AM CDT Fri Jul 24 2026

Updated for the 12Z Aviation Discussion below.

DISCUSSION

Issued at 126 AM CDT Fri Jul 24 2026

Stratus lingers east river this morning, maybe a few pockets of fog too, and still somewhat comfortable temperatures and humidity. Focus for the next several days include a severe weather threat for later this evening and multi-day heatwave.

The 500mb pattern continues to be defined by broad upper ridging across the center of the country. Currently were under northwest flow around the high, which allows for this very subtle wave this evening. The ridge axis builds overhead with increasing heights for the Northern Plains though we retain a northwest component with the ridge axis along the Dakota/MT/WY border. The upper high gradually retrogrades into a more traditions 4-Corners high with a deepening trough across the eastern CONUS.

700mb temperatures on the increase today out ahead of the shortwave, and we'll get up to around +9 to +12C today. Those temperatures continue to ramp-up for the weekend, +13C to +18C in the GFS (which mixes well past this level both days) but +12C to +16C in the other deterministic models. This is roughly 2 standard deviations above climo, 500mb temperatures are also a standard deviation above climo. While we'll see "relief" from this extreme heat, 700mb temperatures are still a standard deviation above climo for all of next week. Thus temperatures will average this weekend 10F to 20F degrees above climo, and 5F to 15F for next week. The one thing that we cant quantify, and remains as a generalization at this point is what impact high smoke will have on temperatures.

CAMS still attempting to generate storms along a boundary up across northwest/north central South Dakota late this afternoon/evening. Convective modus operandi is something like high based storms, up around 10kft, with skinny CAPE and dry atmosphere up above 500mb. Thus, it'll be outflow winds and with such a strong CAP, they'll probably blow themselves out despite moving relatively quickly with 40-60kts in the convective layer. As such, not expecting much overall moisture potential. HREF member postage stamps 24 hour rainfall not showing much for the CWA save an isolated streak or two of 1/4" to 1/2".

Side note. Looks for some Coteau winds with a southwest oriented low level jet. 1/2 km winds are about 40kts tonight.

Very deep mixing despite warm temperatures aloft, can't rule out an isolated daytime driven storm Saturday evening, but more likely is the potential for elevated convection associated with a plume of moisture aloft coming around the high from the Intermountain West. That same wave is responsible for the Day 3 risk area in Minnesota which features more of a pulse convection regime under weaker although unidirectional steering flow.

As for heat headlines, still a little too soon for an advisory, but deterministic NBM is well into criteria both Saturday and Sunday. 25th-75th percentile ranges in highs is 3-8F for both days though this is removing the higher biased (overly mixy) GEFS. 25th-75th range in NBM dewpoints also indicates quite a bit of uncertainty at 13 to 20F (mid 50s to low 70F). Aside from showing a likewise overly mixy GEFS bias, additional uncertainty added as corn is at its potential peak ET, but being tempered by the regional lack of consistent moisture. Looking at just an EC/Canadian ensemble suggests dewpoints may end up being a little underdone in the NBM.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 623 AM CDT Fri Jul 24 2026

Terminals KABR,KATY,KPIR,KMBG

Initial focus is on low stratus/fog this morning, the convection potential late this afternoon and during the evening hours. First for the fog/stratus, there's been some eating away at southwestern portions of the stratus, allowing it to sneak into KABR. That's allowed for fox to develop in it's place and expect any fog this morning to diminish over the next few hours. Confidence is a little lower on the departure of the low stratus, but with increased mixing and a shallow moisture layer, it too should dissipate from southwest to northeast through the morning.

Focus then turns to the convective potential late this afternoon/evening. Not significant changes with the latest models runs, so have continued to show PROB30 for KABR/KMBG between 22Z-03Z (moving quickly from northwest to southeast). We will likely be able to fine tune the timing and add a TEMPO/FM group with the 18Z TAF.

ABR WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None.