textproduct: Aberdeen

KEY MESSAGES

- Cold temperatures expected tonight with lows in the single digits below and teens below zero. Wind chill values will range in the teens and twenties below zero east of the Missouri River.

- Downslope winds expected in the Sisseton Hills region on Thursday, with gusts potentially over 40 mph. This may create areas of blowing/drifting snow.

- Snow chances (20-40%) return Friday and Saturday through early next week as more weather systems have the potential to move through the region.

DISCUSSION

Issued at 216 PM CST Wed Dec 3 2025

As of 2pm, satellite indicates clear skies James Valley and eastward with stratus clouds continuing over central South Dakota and upstream through western ND. Current temperatures range in the single digits to the mid teens, warmest over south central SD. A 1035mb arctic high will be directly overhead by this evening, tracking southeast through the overnight with the center of the high over IA by 12Z Thursday. Winds will diminish west to east across the CWA through this evening becoming light through about 06Z. Models indicate the coldest temperatures will be around the 06Z timeframe before winds shift out of the south/southwest and WAA moves in as the CWA will be on the downstream side of a surface trough that will be positioned south of a low in Canada. HREF grand ensemble 925mb temps look to range between -9 to -17C at 06Z, coldest James Valley and eastward and 850mb temps of -10 to -15C. Kept the trend of dropping the surface temps below mean NBM guidance, closer to the 25th percentile. Forecast lows range from the single digits above zero to around 11 degrees west of the Mo River to the single digits to the teens below zero east of here, coldest over the James Valley. Minimum wind chill values east of the Mo River are forecast to range in the teens to twenties below zero. With the WAA after midnight, we will see temps rise from west to east across the CWA, with temps by 12Z Thursday ranging from the single digits below zero to the lower teens, highest over south central SD. As the surface trough/warm front track east across the CWA through the day Thursday, highs will be warmer ranging in the 20s and 30s!

Our next concern will be the gusty winds over and downslope of the Coteau for Thursday as we see an area of higher winds on the downstream side of this 925/sfc trough over the eastern Dakotas into western MN. HREF 925mb winds indicate speeds between 30-40mph out of the southwest at the top of the inversion layer. HREF is showing surface gusts of 30-45mph with NBM max gusts around the same. Comparing NBM/NBM5.0 is pretty close, about 5kts higher in any one location. The highest winds at 925mb, therefore, the highest gusts at the surface will be in the morning through the late afternoon with winds diminishing towards the evening. EC EFI does highlight this potential well with pockets of 0.6 to 0.7 with EFI of zero for the downsloping wind gusts. Drifting to patchy blowing snow is expected, luckily with the warming temps expected and snow age this should prevent any lofting/widespread blowing snow.

Through at at least early next week we continue in a persistent northwest flow pattern with a near stationary mid level low over the Hudson Bay and a ridge to our west. Models indicate several embedded shortwaves/lows tracking southeast and over the Northern Plains through the extended. With the low mentioned above tracking across Canada Thursday/Friday and its shortwave, HRRR along with ENS/GEFS indicate the chance of flurries/light snow ahead of a cold front late Thursday night through Friday within this surface trough. NBM did not show anything so with collab from the offices, we increased pops and used WPC for QPF to show for this. Pops range from 15-30% Friday with a couple tenths of snow accumulation possible over north central through northeastern SD. Our more notable wave/Clipper low looks to possibly affect the region Saturday, however low confidence exists due to model disagreement at this time on track and intensity of low and where the "highest snowfall" may occur. GEPS has a track more over central SD and ENS more across the northern CWA. NBM probability of 24hr snow ending 12Z Sunday>0.10" is 45-70% with 25% or less for an inch of snow. The good news for now is that we are not expecting heavy snow for any one period during the extended.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1118 AM CST Wed Dec 3 2025

Terminals KABR,KATY,KPIR,KMBG

The stratus layer that was overhead is continuing to decay over KABR and KATY while the stratus continues over central South Dakota. MVFR cigs are forecast to continue at KPIR through the afternoon while the rest of the TAF sites will overall be at VFR. Northerly surface winds will become light and variable this evening, before switching to a southerly direction overnight. Winds will be breezier for Thursday with gusts of 15-20kts at KPIR and KMBG and gusts of 20-30kts at KABR/KATY with the highest gusts at KATY per downsloping winds along the eastern slopes of the Sisseton Hills through the morning and afternoon.

ABR WATCHES/WARNINGS/ADVISORIES

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