textproduct: Aberdeen

KEY MESSAGES

- Active pattern continues, and chances for showers and thunderstorms are in place through at least mid-week.

- Probability of additional rainfall of half an inch or greater through Monday is roughly 30-50% over northeastern South Dakota and western Minnesota, increasing to around 60-80% over central and north central South Dakota.

- There is a Marginal Risk (Level 1 of 5) for all of central and portions of northeastern South Dakota this afternoon and evening. Main threats include wind gusts of 60 mph and hail up to an inch in diameter.

- Another Marginal Risk (Level 1 of 5) is in effect for Monday for parts of northeastern South Dakota. Wind gusts of 60 mph and hail up to an inch in diameter are the main potential threats.

UPDATE

Issued at 1230 PM CDT Sun May 31 2026

Updated discussion for the 18Z TAFs below.

UPDATE Issued at 1016 AM CDT Sun May 31 2026

As of 10am, satellite indicates broken to overcast skies, mainly east of the Missouri River on the northern and northeastern side of a low sitting over northwestern SD with its upper low still spinning away over the northern Rockies. Dry slotting has resulted in overall clear skies over south central SD. Temps range in the 70s and dewpoints in the 50s/60s with winds out of the southeast gusting between 15-25 mph. Mostly dry across the CWA with some light returns on radar over Brown/Spink that may be producing light sprinkles at most. Another plume of rain is over southeastern SD into IA, tracking north. East of the occluded front that will reside over central SD, isolated to scattered showers and thunderstorms are expected to fire up again late afternoon and/or evening and continue through tonight. Quarter size hail and wind gusts of 60 mph are possible with any stronger storm. Other then updating pops, the forecast remains on track.

UPDATE Issued at 638 AM CDT Sun May 31 2026

See below for an aviation forecast discussion for the 12Z TAFs.

DISCUSSION

Issued at 236 AM CDT Sun May 31 2026

Currently (~06Z) keeping a close eye on a line of storms moving into central South Dakota early this morning. Over the past hour, surface observations indicate that win gusts are consistently in the 40-50 miles per hour range, with some stray gusts upwards of 50 (remaining sub-severe for the moment). Expectations over the next couple of hours based on hi-res models are that storms will continue moving into north central South Dakota, gradually deteriorating as they go. Mesoanalysis seems to agree with this assessment based on the idea that shear will decrease moving north. There is still some decent DCAPE (topping out around 900 J/kg) over parts of north central South Dakota that storms are expected to move into over the next couple of hours, so until storms dissipate, an isolated severe gust may still be possible.

Attention then turns to this evening's severe threat, with currently a Marginal Risk for severe storms in place. Storms are expected to take the form of more individual cells, with the best chances for the severe threat located along the James River Valley. A plume of roughly 1500-2000 J/kg of MUCAPE will be in place, and mid-level lapse rates around 7 C/km will also help to support the hail threat. Shear may be a bit of a struggle, but still expecting around 20-30 knots of 0-6km shear lining up with the plume of CAPE (albeit with some local variability). Therefore, can't rule out the potential for severe hail in the areas of strongest shear. Conversely, areas of weaker shear will likely hold the strongest wind threat, mainly due to the potential for collapsing storms. However other than some marginal DCAPE in the 750-1000 J/kg range, not much in the environment points towards the severe wind threat. Low-level lapse rates will be fairly poor (6-7 C/km) and PWATs fall a bit short of the ideal 1.5" for microbursts. That said collapsing storms may be able to produce a stray gust or two, hence the greater potential on the weaker end of the shear. In terms of the potential tornado threat, generally expecting the area of best shear/helicity to be disconnected from the lowest LCLs until later in the evening (as well as fairly low 0-1km shear where storms are present, struggling to get up to 20 knots). The area where all the ingredients could potentially line up appears to be over parts of central South Dakota around sunset and/or over far northeastern South Dakota. However, there is not great consistency between model guidance at this point, so confidence on both the existence and location of possible tornadoes remains quite low.

In terms of rainfall totals still to come, the highest rainfall totals are still expected over central and north central South Dakota. The majority of remaining rain is expected with this morning's convection moving in currently, but scattered showers this evening may also dump an additional quarter to half an inch (though totals will be highly locally varied). Probability to see another half an inch through Monday sits around 30-50% over northeastern South Dakota and western Minnesota, increasing to 60-80% over central and north central South Dakota.

Through the start of the work week, the upper-level low over the western CONUS will continue to bring chances for rain, with perhaps a bit of a break Monday afternoon and evening. The Storm Prediction Center has drawn a Marginal Risk up into parts of northeastern South Dakota Monday, and there does appear to be some CAPE/shear combination in the area during the evening time frame. However, confidence remains quite low due to very few models actually displaying convective initiation, and those that do keeping showers very weak. Both Tuesday and Wednesday evenings show perhaps some better potential for some alignment between CAPE and shear within the Aberdeen forecast area, and severe storms may be possible during those periods. Flow aloft will transition to more zonal by mid to late week. Beyond that point, there is fairly strong consensus in the ensembles in another trough developing over the western CONUS and potentially renewing the rain chances and severe potential for the end of the week to the weekend.

ABR WATCHES/WARNINGS/ADVISORIES

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