textproduct: Aberdeen

KEY MESSAGES

- Light snow moves from the James valley to the Sisseton Hills region this afternoon/evening. Inch or less type snowfalls today.

- Potential for Sisseton hills downslope winds (30 to 40 mph) with blowing snow issues Monday afternoon.

- Next clipper will most likely (60-80% chance of occurrence) be preceded by a brief period of light freezing rain Tuesday morning before temperatures thaw Tuesday afternoon across northeast SD/western MN.

- Northwest winds Tuesday afternoon and evening could gust in excess of 50 to 60 mph across central and north central South Dakota. 45 to 55 mph gusts for the northeast Tuesday evening/overnight.

- Some of the coldest air of this winter season could be settling over the area by the end of the week, including high temperatures around or slightly above 0F and low temperatures down into the single digits below to teens below zero and wind chill values Friday morning as low as -20F to -35F.

UPDATE

Issued at 516 PM CST Sun Dec 7 2025

Added pops west to the Missouri river to account for ongoing snow that the radar is overshooting.

DISCUSSION

Issued at 247 PM CST Sun Dec 7 2025

North to south band of snow continues to migrate east and is just now into Aberdeen. Some light snow continues within the stratus to the west below the radar beam as well. Accumulations on webcams appear to be light, and there has also been some blowing/drifting noted with winds west of here in the 15 to 25 mph range. Still sticking with the "around an inch" messaging with this feature.

As we go through Monday, southerly flow develops out ahead of a weak surface low that moves through North Dakota. A weak gradient for us will limit the ability to mix out the coldest air in the northeast until late, when the low moves into the Red River valley. It should be noted that while flow is mostly unidirectional aloft, there is a weak signal for Sisseton hills downslope winds across the northeast in the afternoon. Despite warming temperatures, there is quite a bit of blowable light/fresh snow up in the northeast, so bumped up the wording for blowing snow in the downslope area as BUFKIT shows about 35kts in the critical layer.

The weak clipper moves on, with a weak ridge in place Monday night/Tuesday morning ahead of a stronger clipper system building in Alberta/Saskatchewan. Between 12Z and 00Z it will have zipped from Canada into the far northeast of South Dakota with a surface pressure of between 992 and 985mb. Each deterministic model has come up with a slight variation with this central pressure over the last few runs, and also with slight variations in placement/track. This plays into confidence in regards to wrap around precipitation (that we will address later).

Firstly, out ahead of this system there is already warm air in place, having previously arrived with the first system and left over from Monday. 21Z Tuesday, 850mb temperatures are mostly in positive territory, though models vary on the strength of the warm air. Generally speaking, its about a standard deviation above climo. BUFKIT profiles suggest there may be enough of a shallow cold layer below the warm nose to present a freezing rain threat with any moisture across the northeast. How much rainfall? NBM 25th/75th range is a tenth to a quarter inch, with a mean of about a tenth or two meaning a large range for just a light amount of moisture. Almost 20 percent of ensemble members fail to generate QPF for Sisseton for that matter. And with warm advection and a shift to westerly flow enhancing mixing, temperatures will continue warm as perception is ongoing. Thus, while freezing rain is a real threat, the duration is limited to mainly during the onset of rainfall with a thaw through the day.

Moisture falling on snowpack and the warming temperatures (on top of what may have been experienced Monday) will severely limit the blowability of any snow on the ground moving forward.

With the onset of cold advection, winds will see a substantial upward trend. A 20 to 24mb gradient, with pressure rises of upwards of 16mb/6 hours will likewise enhance winds. GEFS 850mb winds are 3 standard deviations above climo, and EC EFI/shift of tails continues to highlight South Dakota for potential high winds. As such, issued a high wind watch for most likely areas impacted by high winds. East of this headline, additional headlines will need to be evaluated. Will it require a wind headline or some sort of winter weather related headline with wrap around moisture possibly moving into the CWA? BUFKIT profiles aren't overly supportive for snow (lack of ice in the dendritic growth zone) in the wrap around Tuesday night. Deterministic NBM is only a few hundredths of QPF. There is still time between now and when this system gets going so any slight southward shift in the track would result in high potential for snow falling in a core of 40 to 50 mph winds across the northeast.

That cold air that follows for late in the work week. 850mb temperatures are a standard deviation below climo. While much of the snowpack will have been modified at this point, there may be another round of light snow on Thursday/Friday.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1112 PM CST Sun Dec 7 2025

Terminals KABR,KATY,KPIR,KMBG

IFR stratus will prevail tonight with improvement expected between 15z and 18z Monday. Westerly winds increase in the afternoon with gusts to 25 kts.

ABR WATCHES/WARNINGS/ADVISORIES

SD...High Wind Watch from Tuesday afternoon through late Tuesday night for SDZ003>005-009-010-015>017-033>037-045-048-051.

MN...None.