textproduct: Aberdeen

KEY MESSAGES

- Downslope winds are expected today on and east of the lee of the Prairie Coteau in northeast South Dakota. Visibility could be reduced to one half mile at times.

- A quick moving disturbance will push through the region today into early Wednesday, kicking off a 30-50% chance of light snow over north central and northeast South Dakota and a wintry mix of mainly rain/snow across central South Dakota.

- Very cold air across the region Wednesday and Wednesday night, with lows in the single digits below and teens below zero. Wind chills may reach 15 below to 25 below zero in the James River valley.

- Snow chances (20-35%) return Friday/Saturday as more clipper systems potentially move through the region.

UPDATE

Issued at 1133 AM CST Tue Dec 2 2025

Introduced a short-fused winter weather advisory for "wintry mix" as Pierre PD and Hyde County Sheriff confirmed sleet/freezing rain and snow, respectively, happening between 1030AM and 1130AM. This is for precipitation out ahead of the "above freezing" warm air fetch moving in from the west. So, set the advisory to expire at 2PM, for now, with the expectation that air warm enough to make p-type plain rain or rain mixed with some wet snowflakes should be working into the wint wx advised-counties by then.

Also, see below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 935 AM CST Tue Dec 2 2025

The above freezing surface air temperature is along/west of the western CWA border west river. KPHP is 31F degrees. Fort Pierre RAWS is 27F degrees. Pierre ASOS is 19F degrees. Above freezing temperatures are showing up from Dickinson/Hettinger up in North Dakota down to Buffalo/Faith/Rapid City in South Dakota, and this warm air is expected to advect eastward today on 20 to 30-something knot 0.5km/mixing layer winds. But, right now, all these returns on radar across central/north central South Dakota are just virga returns as the atmosphere works to saturate things down close enough to the ground for precipitation to reach all the way to the ground before evaporating/sublimating. RAP soundings suggest Mobridge/Pierre could be saturated enough to produce precipitation reaching the ground at or after noon CST. P-type still looks predominantly either snow changing to rain or just rain across central South Dakota this afternoon, eventually transitioning back to snow this evening. There is a corridor, though, from appx Gettysburg to Huron where P-type could be rather a mess of snow/rain or freezing rain just depending on what the surface temperature ultimately ends up being from mid-afternoon through early this evening before P-type returns to just all snow later this evening.

UPDATE Issued at 542 AM CST Tue Dec 2 2025

The aviation discussion has been updated for the 12Z TAFS.

SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/

Issued at 504 AM CST Tue Dec 2 2025

Relatively quiet but cold conditions persist for most locations. Temperatures vary widely with subzero readings mainly across parts of northeast SD with single digits above zero elsewhere such as central SD. Skies remain clear for the time being in our east while high clouds are starting to thicken across the western Dakotas. Favorable wind direction across the Missouri Valley is producing another round of low stratus downwind of Lake Oahe and Lake Sharpe. Within some of these areas, dense fog has led to low visibility at times in the Pierre and Mobridge areas. Hi-res guidance had pointed to expansion of some of this fog eastward toward the James Valley through the early morning hours, but has sense backed off. This will be a trend we'll have to keep an eye on through daybreak.

For today, clouds will be thickening out ahead of a warm front that is progged to shift west to east across the forecast area. Low level WAA pattern will develop and try and scour out the arctic air that's been in place. This will be most successful across our western zones where temperatures will reach the low to mid 30s. Sub-freezing temps are anticipated across our east. Southwest flow across the Prairie Coteau will lead to another round of gusty winds in the downslope areas by mid to late morning through at least mid afternoon. There could be localized blowing snow effects in that area. Clouds will continue to thicken in the low to mid levels by midday into the afternoon. Low pressure is progged to track southeastward across eastern ND into west central MN this afternoon. Light precipitation in the form or mostly light snow will be possible across northeast SD and west central MN where BUFKIT profiles suggest the temperature profile through the saturated column remains subfreezing. However, farther west across central SD, some of that warm air will win out allowing for the potential for a rain/snow mix or just plain rain for a period of time this afternoon. As the low levels begin to cool late in the day, a period of a wintry mix or freezing rain will be possible. Guidance continues to suggest QPF will be rather limited through the entirety of this event, so anticipate minimal impacts from a light coating of snow or light glaze in areas that see freezing precip.

That area of low pressure will continue southeast and drag a strong cold front through the forecast area this evening. Winds increase of the north and northwest. Any leftover moisture will accompany the fropa with the potential to see a few more snow showers or flurries into the overnight hours. A CAA pattern sets in overnight with the leading edge of a much colder air mass sinking southward into our area early Wednesday. That pattern is expected to persist through most of the day on Wednesday. Temperatures are likely to be warmest early in the morning on Wednesday and then we should see falling temperatures through the morning and midday hours. Temps may stabilize for a brief time the first half of the afternoon, but anticipate readings will start to plummet by the late afternoon areas. Winds will be strongest during the morning and early afternoon hours leading to wind chill values between 5 and 15 below.

LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/

Issued at 504 AM CST Tue Dec 2 2025

Surface high pressure centered over the region at 00Z Thursday will shift southeast into IA by 12Z Thursday. Southerly winds increase between 06Z and 12Z Thursday with warm air advection developing as well. Therefore, it appears lows Wednesday night may be closer to 06Z, with steady/rising temperatures up through 12Z. Apparent T grids still show wind chills from 25 below to 30 below zero in the James River valley Wednesday night.

GEPS/GEFS/ENS 500mb heights are in good agreement in the mid/upper level pattern featuring a persistent northwest flow aloft during the rest of the extended period. There are a couple waves that moves southeast across the region during this time, but with low confidence on timing and precip chances/placement. Right now, the highlight is on Friday night into Saturday with the highest chances (20-30%) in the forecast. GEFS/GEPS/ENS all show some light QPF over the region as a wave of low pressure slides to our south and we potentially receive light snowfall accumulations across the CWA. Precip chances may eventually increase over the coming day or two.

Temperatures are a bit uncertain as well as the Northern Plains see a battle of air masses, with swings of relative mild air (20s/30s) and colder arctic air with periods of lows in the single digits above and below zero. Inherited max/min temp forecasts reflect this, while low confidence remains on the actual numbers as shown in larger spreads of the 25th/75th values in the NBM.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1133 AM CST Tue Dec 2 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast to deteriorate into MVFR/IFR (cigs) conditions sometime between 22Z this afternoon and 02Z this evening. KPIR is experiencing very light freezing rain and sleet running up to TAF issuance time. And, timing the warm (above freezing) air to be in to the KPIR area by ~20-21Z this afternoon, so only carrying the freezing rain mention for a short time before -ra should be the prevailing condition through the rest of the afternoon into early evening. KMBG/KABR/KATY are expected to remain dry through, at least, 00Z this evening. Then, with the passage of the cold front this evening, light snow or flurries are possible at all four terminals through the overnight into early Wednesday morning. Will introduce snow mention once a better handle on timing/placement can be had. Light to moderate south to west winds expected through the rest of the day before turning more north-northwest this evening and increasing overnight to 10 to 20 knots with gusts up to 30 knots.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Winter Weather Advisory until 2 PM CST this afternoon for SDZ034>037-048-051.

MN...None.