textproduct: Aberdeen

KEY MESSAGES

- There is a Marginal Risk (level 1/5) for isolated severe storms this afternoon through tonight along and east of a line from Sisseton to Chamberlain. Main threats include hail, quarter inch in diameter, and 60 mph winds. Heavy rain is also possible.

- There is an Enhanced Risk (3 of 5) for severe storms for much of central and northeastern SD into west central MN Tuesday afternoon through Tuesday night. Main threats include tornadoes, large to very large hail (2+ inches in diameter), and wind gusts of 70+ mph. Heavy rain is also a concern that could lead to flash flooding.

- The threat of severe weather continues Wednesday afternoon and evening mainly east of a line from Sisseton to Brookings.

DISCUSSION

Issued at 141 AM CDT Mon Jun 8 2026

As of 1am, a bowing line (bow remaining north of the CWA) of strong to severe thunderstorms are over north central SD into ND that has had a history of producing wind gusts between 60-65 mph in our CWA. It will continue to track eastward along ND/SD border. Otherwise current temps range in the 70s ahead of the cold front and dewpoints in the 60s.

By 12Z the cold front (and low along the boundary) will be along the James River with these ongoing scattered showers and thunderstorms continuing ahead of the front, east of the James River. By 18Z, this front will track a bit east and along (or just east) of the Sisseton Hills where it stalls out over northeastern SD/western MN through this evening as the low and front both weaken. Behind the front, high pressure will continue to track eastward and over much of ND/SD by this time. Ahead of the front, temps will warm up into the upper 80s and dewpoints remaining in the mid to upper 60s. Behind the front, highs will only reach the lower to mid 80s with drier air. Went with previous shift and knocked MaxT down a few degrees over central SD. CAPE values this afternoon will increase to about 1000- 2000j/kg (diminishing with sunset) and bulk shear around 30kts out of the southwest through about ~05Z then diminishing. Overall, Cams indicate spotty showers/storms firing up this afternoon to early evening over eastern SD turning more into clusters or small lines, but this looks to form east and southeast of the CWA. HRRR is less excited about this outcome. Additional spotty convection looks possible through early Tuesday morning. Low confidence on where the storms will form and track due to the spotty nature. With this marginal instability some of these storms could become severe with an isolated threat for quarter size hail and wind gusts of 60 mph. Therefore, the SPC has a Marginal Risk, level 1/5, for the threat of isolated severe weather along and east of a line from Sisseton to Chamberlain.

By Tuesday morning, the longwave trough continues over the western CONUS with zonal to slight southwesterly flow aloft. Another strong embedded shortwave will ride along the downstream side of the longwave and over WY/CO with another streak over the western Dakotas, further downstream. Its surface low develops over ~south central MT with its strong warm front stretching eastward along the ND/SD border (or just north). By 00Z the warm front will still extend horizontally across the ND/SD border with its cold front trailing north to south over western SD as the center of the low is forecast to be over ~northwestern SD/southwestern ND by this time. This leaves the CWA within the warm sector as winds at the surface to 850mb will mainly be out of the south ushering in quite the warm and moist air with highs in the 90s (to even around 100 over portions of south central SD) and dewpoints in the mid to upper 60s. Heat indices could be around 100-102 over portions of south central to east central SD. Winds will also increase with a steepening pressure gradient with gusts of 30-45 mph over much of the CWA. So a Wind and Heat Headline may be needed.

This warm and moist air will help the atmosphere destabilize. As of now, REFS/HREF indicate CAPE values of at least 2500 to near 3500 j/kg with potential max over 4000j/kg! Once the cap breaks, showers and thunderstorms will develop Tuesday afternoon through late Tuesday night/early Wednesday morning. Mid level lapse rates of 7- 8.5C/km are forecasted (supporting large hail) and bulk shear of 30- 40kts (perpendicular to front) along with a low level jet of 30- 50kts bringing in that moist air as mentioned. We will also have higher amounts of low level SRH (100-200m2s2) and shear than what we have seen over the past few days with severe weather. So storms that form along and south of the warm front could become discrete/supercells as tornadoes and large to very large hail would be the main threat. Models do hint that as the cold front tracks east this looks to become more of a linear setup as shear will become more parallel to the front aka turning into a wind event (MCS). If this line can bow out then a QLCS setup could be very possible if we get an RIJ and 0-3 line normal shear of 30kts. Again, a bit early for specifics. SPC has expanded the Enhanced Risk (level 3/5) for numerous severe storms mainly for our entire CWA (with the exception of east central SD who is in a Slight Risk, level 2/5). Portions of north central and northeastern SD are in a 5% tornado threat with intensity of Cig1, meaning EF2+ tornadoes possible. Rest of the CWA is a 2% tor threat. As mentioned, winds of 70+ could occur as the storm mode turns linear. Probability of severe wind is 30-44% with cig 1 intensity over portions of north central and northeastern SD into west central MN. Probability of severe hail also ranges from 30-44% Cig1 mainly between the Mo and James River meaning 2"+ inch hail possible. With ongoing PWAT values above an inch, heavy rain would be a concern leading to flash flooding.

By Wednesday morning, the fropa is forecast to lie along the James Valley where it will track eastward as the center of the low tracks northeastward. Once again, highs in the upper 80s to around 90 and dewpoints in the lower to mid 60s over eastern SD will lead to the potential of showers and thunderstorms firing up along and ahead of the front along and east of the Sisseton Hills in the afternoon and evening. The SPC has highlighted a Marginal Risk (level 1/5) along and east of a line from Sisseton to Brookings with the main threats being quarter size hail and 60 mph wind. The threat for showers and thunderstorms continue on Thursday on the wrap around side of this low mainly over north central to northeastern SD/western MN. As of now no severe weather anticipated. We finally will see quieter weather for Friday with quite the cooldown into the weekend with highs forecast only in the 70s.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1218 AM CDT Mon Jun 8 2026

Terminals KABR,KATY,KPIR,KMBG

A line of strong showers and thunderstorms are moving eastward across north central SD and will be affecting KMBG TAF site in the next hour or so. This line of storms will continue to track eastward with KABR between ~08 to 09Z. The main concern will be strong winds associated with this. Vicinity rain showers are currently near KATY with most of this staying mainly east and southeast of the TAF site. These should exit the region this afternoon with additional chances of showers and thunderstorms this afternoon and evening that may affect KATY. Otherwise, mainly MVFR/VFR cigs through the TAF forecast with drops in visibility with any stronger storm. ATY will be borderline IFR ceilings between 10-14Z.

ABR WATCHES/WARNINGS/ADVISORIES

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