textproduct: Aberdeen

KEY MESSAGES

- Freezing rain over far northeastern South Dakota and west central Minnesota will change over to all rain early this afternoon as temperatures warm above freezing. A Winter Weather Advisory remains in effect until 3 PM for far northeastern South Dakota and west central Minnesota.

- Northwest winds this afternoon through tonight will gust in excess of 50 to 65 mph across central and north central South Dakota. Gusts in excess of 50 mph are also expected over northeast South Dakota and west central Minnesota early this evening into the early Wednesday. A High Wind Warning is in effect for these dangerously strong winds.

- Highs will be in the teens to single digits Friday through Sunday. The coldest air will be Sunday morning, with lows in the 0 to -20 degree range. Wind chill values Friday and Saturday morning could be as low as -20 to -30 degrees.

- Multiple rounds of snow will be possible late this week. Northeastern South Dakota into western Minnesota has a 30-50% chance of 2" of snow Thursday through Friday. A band of snow may impact the area over the weekend, although there is still a lot of uncertainty in the tracks and amounts.

UPDATE

Issued at 1050 AM CST Tue Dec 9 2025

Much of Faulk county is now well into the mid 30s for the last hour or two, however the rest of the James valley has been a bit more stubborn in regards to warming up. Winds are shifting to southwest so its just a matter of time, with guidance remaining consistent with its slow gradual warmup. May need to extend the advisory up in the far northeast for a little bit longer though since much of the far northeast is still below 0C.

The 0.08 of rainfall thus far at KABR has also rendered our snowpack unblowable for the future winds. This rainfall continues to progress east southeast, now into Day, Marshall and Clark counties. Tracking its progression into the afternoon, there may be a northern cutoff where less rainfall falls into the snowpack, for far northern Roberts and parts of Traverse counties, but overall the expectation is with the rain and temperatures, this snowpack will react very little to the incoming winds.

In regards to winds speeds, very little has changed with this update. Cold advection is a little convoluted to start with two separate areas of a tight 925mb gradient, one split the CWA north and south at 21Z headed southwards and the second, northwest to southeast coming in closer to 00-03Z (tightest across the northeast CWA). The HREF captures the duality of this surge in winds well, with a surge west river early this afternoon which will leak into our western CWA, and more broadly around 00Z. In- between there is some less efficient mixing but some fraction of that 50-60kts at 850mb will still manage to reach the surface. These most intense wind values start dropping off after 03-04Z as 1/2km winds begin a gradual downward trend.

Lastly, many of the CAMS have wrap around snow showers into the northeast of South Dakota and our counties in Minnesota. BUFKIT profiles also support a cooling of profiles but there are issues with ice in the dendritic growth zone until after about 03-05Z. HREF highlights the top of the Coteau for a 1/4 to 1/2 inch per hour snowfall rates from 04 to 09Z, with a mean accum of 2" at its peak. This is just slightly out of phase with the strongest winds, which mentioned above start dropping after 03-04Z. HREF analog for blizzard conditions highlights the whole northeast (northern Coteau through western MN) with just a 20 to as high as 40% probability.

SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/

Issued at 357 AM CST Tue Dec 9 2025

At 3 AM CST, there was a pocket of freezing fog in the James River valley (mainly Brown County), although, Watertown briefly dropped visibility into some fog as well. It is cloudy over the CWA this morning, with temperatures west of the James River valley predominantly in the mid 20s to upper 30s (warmest out along and west river). Within and east of the James River valley, temperatures were mainly in the teens to mid 20s. Precipitation is overspreading the northern high plains of Montana and far western North Dakota, heading in this direction.

Only adjustments to the Winter Weather Advisory for freezing rain was to add a couple more tiers of counties for a few hours for the early part of this morning when WAA-forced precipitation (rain) reaches north central South Dakota (expected prior to 12Z). The MRMS Sfc Probability of subfreezing road temperatures over the next 60 minutes supports this brief expansion of the freezing rain headline over to Corson/Dewey counties from 11Z to 16Z this morning. Did break off a piece of the pre-existing "northeast SoDak" wint wx headline area in order to create a "between the MO and James River valleys" hazard segment to include Campbell, Walworth, Potter and Faulk counties, running from 12Z to 18Z. Otherwise, the rest of the Winter Weather Advisory is basically the same, timing/coverage-wise, and the High Wind Warning remains in place, unchanged from what the Monday day-shift crafted when they issued the High Wind Warning.

Should be looking at a corridor of time this morning when freezing rain is happening from west to east across the CWA, predominantly throughout and north of the U.S. Highway 212 corridor. Strong post- cold frontal 0.5km mixing winds on a 16+hpa 6-hourly pressure rise bubble should be able to produce sustained winds at 40 mph for an hour or more, or gusts well in excess of 60mph sometime between late this afternoon and late tonight. Regarding post-clipper system snowfall on the backside of the system late tonight into Wednesday morning, there is now a small section of terrain-influenced "near blizzard"-type blowing snow being produced by the blowing snow model across a portion of Marshall and Roberts counties tonight between roughly 05Z and 10Z when winds and temperatures and upslope on the Prairie Coteau may be able to overcome the general lack of any sort of meaningful snowfall-rates to produce some localized/isolated rather poor visibility in falling/blowing snow. A new wrinkle for the next shift to debate.

Despite the warming process coming to an abrupt halt yesterday at the James River valley (temperatures did warm up quite a bit west of the James River valley yesterday), still going with a significant warm-up today, CWA-wide. So, after two days of snowmelt, topped with several hours of rainfall potential, there should be no blowing snow concerns across central/north central South Dakota. Once temperatures fall back below zero this evening, the remaining modified snowfield should transition into blocks/sheets of ice. Similar outcome expected across northeast SoDak and west central Minnesota this afternoon/evening, although CAMS/deterministic GSM's do hint at there being some falling snow (generally less than an inch except up on the far northern portion of the Prairie Coteau) potential later tonight into Wednesday morning across far northeast South Dakota and west central Minnesota.

After how warm it will be today, Wednesday will feel like quite a shock to the system, when high temperatures will only be in the upper teens to low 30s over the CWA.

LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/

Issued at 357 AM CST Tue Dec 9 2025

The pattern of the Northern Plains remaining on the front side of the upper-level ridge over the western CONUS. With this setup, a couple of jet streaks will move over the area, providing enough divergence aloft to support precipitation Thursday through early Friday. Model soundings indicate that snow is the most likely precipitation type through the event, but there will be chances for rain and freezing rain as well. The latter precip types could occur with a de-saturation of the DGZ aloft during the event, which could transition from ice formation to liquid formation aloft depending on how cold temperatures at the top of the saturated layer remain. Latest ensemble medians have broad coverage of 0.10"-0.20" in liquid totals through Friday morning, with the highest totals over north central into northeastern South Dakota. This will translate to around 1"-2" across much of the forecast area, although varying snow to liquid ratios (~10:1 over north central South Dakota ranging to ~15:1 over northeastern South Dakota) may create a disparity between the highest liquid equivalent and highest snowfall locations. Latest probability of at least two inches peaks over northeastern South Dakota, ranging from 30 to 50 percent.

With this setup, a strong blast of cold air is expected to move into the region Friday into Saturday. 850mb temperatures by Saturday morning are expected to be in the teens below 0 Celsius, which is below the 10th percentile for this time of year. The presence of this cold air will lead to overnight lows at the surface below zero Fahrenheit Friday and Saturday mornings. At these temperatures, wind chills are expected to reach -20 degrees Fahrenheit in most of north central and northeastern South Dakota, and potentially even approach the Cold Weather Advisory Criteria of the northern counties of -30 degrees Fahrenheit. Friday morning is of particular concern, because while temperatures are slightly warmer than Saturday morning, northwesterly winds of 20-25 miles per hour gusting to 35 overnight will counteract that difference. The latest long-range ensemble guidance put the probability of hitting -30 degrees Fahrenheit for the minimum overnight wind chill in northeastern South Dakota at 20- 40% on Friday morning, easing up to around 10-20% Saturday morning.

Yet another round of snow may impact the region this weekend, this time being more banded with a swath of heavier precipitation totals. There is still a lot of uncertainty remaining, but it is worth noting that forecast snow totals have jumped up over the latest forecast cycle. The latest NBM currently puts a band of 50% probability to see 2" of snowfall accumulations, with a band of 20- 30% chance for up to 4".

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1135 AM CST Tue Dec 9 2025

Terminals KABR,KATY,KPIR,KMBG

Freezing rain remains possible at ATY for the next hour at least temporarily, as temperatures have already risen to 32 degrees and will continue to change over to all rain through the rest of the afternoon hours. MVFR ceilings across ND will begin to sink across the area this afternoon, with MVFR ceilings expected from 20Z through the rest of the period at ABR and ATY. VFR conditions are expected to continue at PIR/MBG. The other main concern is strong winds, in initially in the form of low level wind shear and then gusting 40-50kts late this afternoon through at least this evening, peaking at MBG/PIR from 20Z Tuesday-09Z Wednesday and at ABR/ATY 00Z-09Z Wednesday.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Winter Weather Advisory until 3 PM CST this afternoon for SDZ008- 021.

High Wind Warning from 3 PM this afternoon to 6 AM CST Wednesday for SDZ006>008-011-018.

High Wind Warning until 2 AM MST Wednesday for SDZ003-015.

High Wind Warning from 3 PM CST /2 PM MST/ this afternoon to 3 AM CST /2 AM MST/ Wednesday for SDZ004-005-009-010-016-017- 033>037-045-048-051.

High Wind Warning from 6 PM this evening to 6 AM CST Wednesday for SDZ019>023.

MN...Winter Weather Advisory until 3 PM CST this afternoon for MNZ039- 046.

High Wind Warning from 3 PM this afternoon to 6 AM CST Wednesday for MNZ039-046.