textproduct: Aberdeen

KEY MESSAGES

- Widespread rainfall Saturday evening through the day Sunday. Main focus area is central South Dakota. Probability of exceeding 1" rainfall is 70-90% along and south of a line from Eagle Butte to Fort Thompson. Potential rainfall amounts drop off dramatically with little if any expected east of a line from Aberdeen to Watertown.

- Faster moving system Monday night. Additional light amounts of moisture, but more convective in nature so low confidence on amounts. Severe weather unlikely.

- Temperatures remain near to slightly below normal through next week. Coolest day being Sunday at 5 to 20 degrees below normal.

DISCUSSION

Issued at 1242 AM CDT Sat Jun 20 2026

Fires in the Intermountain West have generated smoke which is being advected up ahead of the next system. As such, looking at the HRRR vertically integrated smoke, there is a plume that moves out over South Dakota later today. Smoke is at relatively low concentration as it moves into the state, and with low level flow off the high to the north, non-existant at the surface. It may play some small part in affecting high temperatures today, but at the low concentrations in the HRRR will not adjust NBM temperatures.

Focus shifts to moisture associated with the wave that passes across the area later today through most of Sunday. The wave is sandwiched by jets to the north and south, resulting in a slow overall motion, and that long duration will aid in the overall moisture amounts. Synoptically, this is also mainly a rain-maker as profiles remain moist adiabatic aloft, with some skinny CAPE, no shear, and an inversion and a cooler low level airmass associated with flow off the high into the system.

Forecast QPF continues to drop, and is down about an inch since this time last night. We now fall just a little below the mean NBM, but that still gives us greater than an inch moisture overall for central South Dakota. Better refinement is evident across north central/northeast South Dakota with much lower moisture potential for Aberdeen/Watertown (few hundredths) and Mobridge still on the periphery with 2/3". Again, focus remains across central South Dakota with at least some drought relief, with the NBM probability of exceeding 1" moisture around for Pierre at 80% and 2" at 40%. Profiles for Aberdeen/Watertown continue to show quite a bit of dry air on the northern periphery of the system, and probabilities drop rapidly off after exceeding a tenth of an inch. So those (Pierre v Aberdeen/Watertown) are the bookends. In-between much less confidence in overall moisture potential.

A clipper system moves in late Monday as the next system. QPF focus is across the western Dakotas & eastern Montana/Wyoming Monday afternoon with a rapid transition to the east. Thus, a lot less moisture potential with this system. Profiles are dominated by skinny CAPE and weak wind shear below 500mb. Not really much mid- level thermal advection on the backside, nor a strong gradient. NBM post frontal winds mix out at 20 to 30kts.

A stronger ridge, with a wave under the ridge type system for late in the week. Northwest flow before that arrives, and 700mb temperatures not being overly warm means we cant rule out continued hit and miss weak thunderstorms during the interlude. With the mild mid level temperatures and a northwest flow pattern most of the forecast period, daily temperatures remain mild with low humidity.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1242 AM CDT Sat Jun 20 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for all terminals. Light winds through the overnight hours. Rain moves into the KPIR area late in the day and through the overnight, with lower CIGS late in the TAF period.

ABR WATCHES/WARNINGS/ADVISORIES

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