textproduct: Aberdeen

KEY MESSAGES

- A Marginal Risk (level 1 out of 5) for severe weather has been issued for areas just south and east of the Watertown area Thursday afternoon. Large hail to 1 inch in diameter and damaging winds of 60 mph will be the main threats.

- After a dry couple days Friday and Saturday, an active northwest flow aloft pattern will persist through the end of the week into early next week. Periodic chances for showers and thunderstorms will continue across the region.

UPDATE

Issued at 845 AM CDT Wed Aug 19 2026

Complex of showers and thunderstorms is exiting the CWA to the southeast. Had earlier made further adjustments to PoPs to account for radar trends. Marginal Risk has been removed from the entire CWA for today, so threat for severe storms has diminished across the region today/tonight. Also made adjustments to sky cover to better align with satellite trends.

DISCUSSION

Issued at 207 AM CDT Wed Aug 19 2026

As of 2 AM CDT...scattered showers and thunderstorms continue to track southeast through portions of the forecast area...mainly across parts of central and south central SD. There will be an isolated strong wind threat through the early morning hours for parts of south central SD and possibly as far east as the James Valley. This activity is in response to a well defined shortwave trough on water vapor moving east-southeast across western and central SD. This feature is progged to continue tracking southeast into sections of eastern and southeastern SD the remainder of this morning into the early afternoon. Precip chances will follow with it as parts of our southern/southwestern zones will continue to hold onto showers and storms through about mid morning. Drier conditions should settle into the area for the afternoon hours. Although, some spotty afternoon cells could be possible as a sfc warm front lifts back to the north and east across the CWA. Instability and shear values during peak heating today don't look too impressive with MLCAPE values of 1000-1500 J/kg across central parts of SD and 0-6 km bulk shear values of 25-30 kts. SPC has maintained a Marginal Risk (level 1 of 5) for severe weather from south central sections of SD northeast into portions of the James and Big Sioux Valleys. Main threats will be large hail to 1 inch and damaging winds of 60 mph.

Tonight, with a sfc high centered east of our region, a sfc low and associated trough will track eastward into the central and eastern Dakotas. MUCAPE values are progged to be 500-1000 J/kg and 40-50 kts of deep layer shear are progged to be present early Thursday morning across northeast SD into west central MN. Expect another round of scattered showers and storms in these areas after midnight through at least the daybreak hour and possibly lingering longer into mid morning. During peak heating Thursday afternoon, MLCAPE values will build to about 1000-1500 J/kg and deep shear looks to top out around 35-40 kts across eastern SD and western MN. We could potentially see some re-develoment of storms during the afternoon hours across our far eastern zones, although by then the better chances could be just off to our east and south. SPC's Marginal Risk (level 1 of 5) for severe weather clips portions of Hamlin and Deuel Counties Thursday afternoon. Thursday night into Friday will feature a cold front swinging south and east across the forecast area. Sfc high pressure will move southeast across the eastern Dakotas and western MN on Friday as the western CONUS upper ridge starts to amplify. This will lead to increasing heights across the Northern Plains and should bring a bit a short reprieve from the the nearly daily or nightly passages of upper shortwave troughs.

With that said, some guidance is hinting at yet another upper trough passage Friday night into early Saturday somewhere across the eastern Dakotas or northern MN. Models are at odds on where this feature could potentially track. Confidence remains low and we'll keep the forecast dry for now. Upper ridging is progged to crest over the area this weekend. Dry conditions are expected Saturday into early Sunday. By late in the weekend, another upper trough working out the Pac NW will crash over the top of the ridge leading to our next round of showers and storms the latter half of the weekend. Knocking down the upper ridge looks to be temporary as 500mb heights bounce back early next week. Temperatures at or above normal will return to the region Monday through Wednesday. On and off again chances for showers and storms are expected to continue as an active northwest flow aloft pattern remains entrenched across the region.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 607 AM CDT Wed Aug 19 2026

Terminals KABR,KATY,KPIR,KMBG

Scattered showers and weak thunderstorms are currently tracking south/southeast across portions of central and northeastern SD near KABR and KATY terminals. These storms will be over/near the terminals for the next several hours. No severe weather is anticipated, however, stronger storms could produce wind gusts of 25kts or so and pea size hail. Otherwise, dry conditions before isolated to scattered chances of showers and thunderstorms move back over portions of north central and northeastern SD late this afternoon/tonight into the overnight hours, mainly near KABR and KMBG. Otherwise, VFR cigs forecast through the end of the TAF period.

ABR WATCHES/WARNINGS/ADVISORIES

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