textproduct: Aberdeen

KEY MESSAGES

- A system will bring a band of snow tonight through Saturday morning with accumulations of 2 to 4 inches, mainly along and south of a line from Mobridge to Miller. A Winter Weather Advisory is in effect for this area 9pm tonight through 9am CST Saturday.

-Cold air will remain in place through Sunday. The coldest temperatures will be Sunday morning, with lows of -5 to -20. Wind chills of -20 to -35 are forecast Sunday morning.

UPDATE

Issued at 510 AM CST Fri Dec 12 2025

Updated discussion for the 12Z TAFs below.

SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/

Issued at 254 AM CST Fri Dec 12 2025

As of 230am, mainly overcast skies are present with light snow showers clipping far northeastern SD associated with a cold front attached to its low over Manitoba. Over the next few hours we will continue with chances (20-35%) of snow before the fropa exits the region. Otherwise flurries could be possible over south central SD early this morning ahead of the incoming system. We have already seen our highs today, which around 2am ranged in the upper teens to the upper 20s, warmest over south central SD. For today a high will be positioned to our northwest in Canada with an area of low pressure and a northwest to southeast oriented frontal boundary positioned over the Northern Rockies. Between these systems, and help from another shortwave moving in from the northwest, a band of accumulating snow will set up northwest to southeast from northern MT, through SD, and into northeastern NE today through Saturday. For our CWA, CAMs overall agree on light snow moving in west of the Missouri River this morning through the midday with the band of snow expanding southward and eastward during the overnight/early morning hours and exiting our far southern and southeastern CWA by late Saturday morning. CAMs also indicate that between ~09Z-12Z there could possibly be a very narrow, more moderate transient band of snow (0.50-0.75" per hour/HREF), within this larger band of snow setting up over south central SD. The highest pops of 80-100% will lie along and west/southwest of a line from Mobridge to Miller between 00-12Z Saturday with the 90-100% pops from southeastern Dewey through Sully/Hughes and into Buffalo counties where the CAMs show this potential for a moderate band of snow setting up as mentioned.

The good news with this system is that the ptype will be all snow this time around as the entire saturated column will sit below zero C. NAM soundings at KPIR/KMBG both indicate that this saturated column, and its vertical motion, pretty much sits within the DGZ zone this evening through Saturday morning (when we have the highest pops), therefore, leading to higher snow ratios (better dendritic formation of snowflakes). NBM snow ratios range from 16:1 to 21:1 which fits right in the ballpark with this system. Model consensus between the global and short term ensembles along with NBM/WPC all indicate QPF values ranging from 0.1 to ~0.25" for this band of precip along and south/southwest of a line from McIntosh to Miller with snow amounts for this area ranging from 2-4", with isolated areas of 5", highest over south central SD. Probability of 6" is 25% or less for portions of south central SD per NBM and 5% WPC. There is a 1/10 chance of snowfall amounts of 5-7" if we see a heavier band setup than forecasted. Also, any shift north or south in the track of the system will lead to a shift in where the higher snowfall amounts occur. A Winter Weather Advisory has been issued for all of south central SD and portions of north central SD from 03Z-15Z Saturday. Blowing snow should not be an issue during this time as winds overall remain less than 20kts for the advisory area.

With cold arctic air plunging southeastward today, temps will continue to drop with temps by 18Z only ranging in the single digits above zero to the lower teens. 925mb temps overnight range from -16 to -25C. This along with snowpack I went below guidance with lows ranging in the single digits below zero to the single digits above zero. WInd chills will range in the teens and twenties below zero. Highs for Saturday are only expected around zero to the single digits above zero.

LONG TERM /SATURDAY EVENING THROUGH THURSDAY/

Issued at 254 AM CST Fri Dec 12 2025

Opening at the end of the day Saturday, we have a 1040mb high pressure system more or less overhead, with the core of coldest 850mb temperatures across northern Minnesota. These temperatures represent a standard deviation below climo for mid-December. It also puts the CWA under ideal radiational conditions. High temperature Saturday is right around zero, so while the NBM is down to 10 to 20 below for a low, the 25th/75th range adds an additional 5 to 10 degrees of wiggle room on the lows. Given the setup, especially for Aberdeen, 20 below seems warmly optimistic. NBM does bring in some cloud cover, however looking at the GFS/NAM BUFKIT there is little moisture in the profile. Farther west, for the Missouri valley, return flow after midnight may aid in just enough mixing to arrest temperature falls, though this area will have ample fresh snow cover.

Return flow (southerly) for the day Sunday means slight warming but with a very cold start, and a intensifying gradient, wind chills will not improve rapidly during the morning so thinking is any headline will have to reflect this. BUFKIT profiles show the development of a rather extreme inversion just off the surface, though with a due south wind, limiting mixing. Will need to monitor the Sisseton hills downslope area for enhancement as well.

A ridge aloft upstream helps buckle the jet northwards early next week bringing an end to the northwest flow regime. This allows for a modified Pacific airmass to migrate into the region Monday with much warmer air aloft. 850mb temperatures increase to a standard deviation or two above climo. Monday we are under a weak surface high, with light winds which limits mixing thanks to our snow cover. NBM 25th/75th spread is greatest across the far northeast and western Minnesota with the lower bounds in the mid 20s and upper bounds in the mid 30s. Looks like deterministically, the forecast for much of our area falls closer to the 25th percentile.

A low in central Canada increases low level westerlies across the Dakotas, and with the better mixing profile, more confident in an actual warmup Tuesday. There may be a period in the morning with some Sisseton hills downslope potential but snow cover out there got heavily modified and uncertain if anything recent has fallen and is thus blowable after our last mid-week thaw. Regardless, overall doesn't appear to be a prolonged event as winds shift to westerly.

As is typical with this flow pattern for the middle-end of next week, overall not a lot of confidence in regards to timing and strength of waves/systems, but overall trends are for weaker systems in comparison to the recent pattern and thus just some low chances for moisture.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 510 AM CST Fri Dec 12 2025

Terminals KABR,KATY,KPIR,KMBG

MVFR cigs continue across the TAF sites early this morning. KABR/KATY will jump between VFR and MVFR through the TAF period while KMBG/KPIR will lower to IFR cigs around 06Z as snow will move into this area through 12Z Saturday, reducing visibilities. Winds will continue to be gusty this morning, ranging between 25-35kts, diminishing across the area this evening and tonight.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Winter Weather Advisory from 9 PM CST /8 PM MST/ this evening to 9 AM CST /8 AM MST/ Saturday for SDZ003-015-033>037-045-048- 051.

MN...None.