textproduct: Aberdeen

KEY MESSAGES

- There is an Enhanced Risk (level 3 of 5) for scattered to numerous severe storms over portions of central and northeastern SD. Storms are expected to form over central SD this evening and track east and southeast through the overnight hours. The main threats are 2" or greater diameter hail and wind gusts in excess of 70 mph. A tornado or two will also be possible.

- There is a Slight Risk (level 2 of 5) for scattered severe storms Tuesday evening through Tuesday night for all of central and portions of northeastern SD. There is Marginal Risk (level 1 of 5) for portions of northeastern SD through west central MN. Main threats include 1 to 2 inch diameter hail and wind gusts of 60 to 70 mph.

UPDATE

Issued at 630 PM CDT Mon Aug 10 2026

Aviation discussion updated below for the 00Z TAFs.

UPDATE Issued at 307 PM CDT Mon Aug 10 2026

The SPC has upgraded portions of the slight risk to an Enhanced Risk (level 3/5) along and east of a line from Eagle Butte to Murdo. Storms are still expected to form over central SD this evening and track east and southeast through the overnight hours. This enhanced area has also been upgraded to a 30% Cig 1 wind probability where the bulk of the upscale growth/cold pool formation into an MCS (perhaps bowing MCS) overnight will combine with bulk shear and steep low to mid level lapse rates. A tornado or two will also be possible along with hail 2 inches in diameter or larger.

DISCUSSION

Issued at 139 PM CDT Mon Aug 10 2026

West to northwest flow continues aloft over the region per a weak broad ridge over the western CONUS. Another weak embedded shortwave (500mb winds 35-45kts) will track east/southeast across SD this evening into IA/MN through early Tuesday morning with the bulk of the vorticity over central through southeastern SD. At the surface, a weak low will be over southwestern SD this evening with an inverted trough extending northeastward from it through SD/MN through the overnight hours with not much movement with the low and a slight track southeast with the trough. 700mb temps are not overly strong, ranging from +8 to +14C this evening, warmest over south central SD. With 850mb to sfc winds out of the south and southeast, this continues to usher in warm moist air with dewpoints rising into the upper 60s to potentially lower 70s, before winds switch more east/northeast overnight. There is no lack of instability with HREF mean CAPE between 2000-3500j/kg (RAP=3000-4000j/kg) this evening to around 1500-2500j/kg by 06Z with the highest amounts over central through southeastern SD. Bulk shear will range between 40-50kts through the overnight with 0-3km SRH 200-400m2s2, highest over south central through east central SD, and steep low to mid level lapse rates. Only thing really lacking is a strengthening LLJ overnight.

This sets the stage for showers and thunderstorms to fire up starting this evening as the cap erodes, however, it remains tricky with several potential outcomes. Overall consensus per CAMS has discrete cells/clusters developing over north central SD/ND and potentially one over south central/southern SD. This earlier stage of development and storms tracking over central SD is when the largest hail (potentially over 2") and the threat of tornadoes would be with any supercells given surface based storms interacting with surface trough (and moderate Cape/shear) with 0-1km SRH between 100-200m2s2 and stp of 1. As mergers and additional development occurs, storms will grow quickly upscale as they track east/southeast into an organized cluster (MCS) with possible bowing segments if an RIJ develops. However, HRRR/REFS has nothing developing until around midnight with storm mode being more clustery over east central through southeastern SD. Between the individual CAMS, there are differences in where these storms initially develop, whether 1 or 2 areas of convection will merge or track separately, timing/location of upscale growth to a MCS, if bowing segments do form, and and exact track of it. Due to this, confidence is very low on which scenario will play out at this time. So continued with sticking with the NBM for pops given this uncertainty which does a good job, keeping pops broad due with highest pops (50-75%) over central through east central SD where the majority of the CAMS show this area being impacted the greatest and where our best instability lies and energy aloft. Another caveat is the ongoing thick smoke from the PacNW blanketing the region. If thick enough, this could damper instability and convection and we get little in the way of storms.

With this, there is a Slight Risk (level 2/5) per SPC for much of the CWA (with the exception of far NESD/MN which is in a marginal risk) for the potential of scattered severe storms. There is a cig 1 hail threat (potential 2"+ in diameter) given supercell potential, mainly along and west of a line from Aberdeen to Huron. SPC has added in a 2% tornado threat along and south of a line from Mobridge to Redfield where tornadoes are possible mentioned above. Wind gusts of 60-70 mph are possible with the potential for winds in excess of 75mph if an MCS develops especially for locations where the potential bowing system could track. Therefore a Cig 1 is outlooked for wind mainly along and east and southeast of a line from Gettysburg to Pierre where some of the CAMs indicate this greatest potential.

Not much change aloft Tuesday and Wednesday in ongoing west to northwest flow aloft and potentially weak embedded shortwaves tracking across the region and a front tracking southward out of Canada Wednesday evening/night. Adding in daytime heating/instability and ongoing low level moisture and shear, we will continue with the threat of showers and thunderstorms each afternoon/evening into the overnight hours. A Sight Risk (level 2/5) is in place mainly west of the James River and a Marginal Risk ( level 1/5) east of James River Tuesday. A Marginal Risk extends along and south of a line from Eagle Butte to Brookings Wednesday. Broad ridge that has been over the western CONUS will shift eastward and over the central CONUS for the end of the week. Add in surface features and additional instability and chances for showers and thunderstorms continue through the end of the week with low confidence this far out on any severe weather potential. As of now ML guidance keeps the threat low. Behind fropa and cooler air aloft per deepening low over Canada, highs will be cooler only in the 70s for the end of the week and into the weekend.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 630 PM CDT Mon Aug 10 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast at the start of the TAF period. There is a threat of TSRA/+TSRA across the region later tonight, but confidence is low on areal coverage and overall placement of storms. Using PROB30 to handle this for the time being. Any stronger TSRA/+TSRA that move over a TAF site could bring MVFR/IFR VSBY. There are also suggestions for MVFR/IFR CIGs and FG/BR in the KATY region early Tuesday morning and have inserted mention of this into the TAF.

ABR WATCHES/WARNINGS/ADVISORIES

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