textproduct: Aberdeen

KEY MESSAGES

- A few snow showers will pass from west to east this afternoon across the northern tier of the state. Limited accumulations expected.

- A clipper system brings strong winds in for Thursday afternoon and evening, although confidence is low in regards to peak strength/timing of the winds. Winds potentially could gusts up over 60 mph in central/north central SD and above 50 mph for the Sisseton hills region. High Wind Watch has been expanded into the James valley.

- Mild temperatures and dry conditions will raise fire weather concerns for Thursday afternoon as well. Fire Weather Watch is in effect. Very little overall precipitation with this system. - Another area of low pressure will bring a 50 to 70% chance for snow or a mix this weekend. High and low temperatures Sunday into Monday will be about 15 to 20 degrees below normal.

UPDATE

Issued at 615 AM CDT Wed Mar 11 2026

Fog remains over much of north central SD early this morning, which will mix/improve to 5 miles visibility or higher by 18Z at all locations. Most areas have been experiencing variable visibility between 1/2 mile and 3 miles. The ongoing forecast remains on track this morning.

DISCUSSION

Issued at 216 AM CDT Wed Mar 11 2026

Snow continues to move east and out of the CWA. Focus for today is the instability created by cool mid level temperatures, about a standard deviation below climo at 700mb with an upper trough directly overhead. NAM BUFKIT profiles indicate steep low level lapse rates, and a decent convective layer from 5 to 15kft, deep enough to generate snowfall, with a freezing level of 1 to 2kft. CAMS also picking up on the convective nature of the environment. Snow Squall parameter in the NAM highlights the northeast this evening, however CAMS don't look quite so organized in their depictions. Given the nature of convection, NBM smooths it out so have input a blend of CAMS to better detail the nature of precipitation for the afternoon.

Ahead of the Thursday system, NAM BUFKIT profiles indicate a brief period of favorable downslope conditions for the lee of the Sisseton hills, with 50kts in the critical layer. Flow is mostly westerly and the inversion weak so probably not going to exceed 60 mph at Peever, however the HRRR and ECAM both top out in the low 40kt range so up around 50 is definitely possible.

With the Thursday clipper, there is better consistency in model placement and timing of the low track/intensity, though the use of the adjective 'better' here is me being passive aggressive. The GFS still has the most consistency with a low moving through the far northeast of Montana/northwest North Dakota straight through to Fargo/Grand Forks and then making a short loop into the Western Lakes region. The Canadian takes a flatter trajectory along the ND/SD state line into the Western Lakes region. The EC is now in line with the GFS, whereas yesterday it was quite a bit weaker until the system rapidly deepens as it approached the Western Lakes region. And the NAM is the largest outlier with the low tracking along the International Border into northern Minnesota. And there is still about a 10mb difference in the central pressure of the low between models. Ergo the really really low confidence in regards to wind speed intensity/timing and precipitation. The GFS is probably the higher end in regards to pressure rises on the backside of the system at 12 to 17mb per 6 hours. There is also a duel nature to the cold advection with two surges showing up in the 850mb analysis between the main deterministic models. The initial surge of modified Pacific air goes across the area Thursday in the warm sector, followed by the Arctic front Thursday evening. These being well separated in time in the GFS/NAM with the EC on the opposite spectrum with just a broad cold advection regime. This will influence when we go from a warm to weakly cold advection regime followed by the stronger cold advection. Unfortunately there is a lot of wind potential if we can efficiently mix with 60-100ks of unidirectional flow in the mid levels, so the ceiling on strong winds is pretty high, but the confidence on achieving such strong winds is low. Previous forecast input a blend of higher winds to account for the strong cold advection and pressure rises associated with the system.

A last minute add on looking over the CAMS wind output lends a little more confidence on expanding headlines for high winds as well as the fire danger/red flag potential thanks to a wind shift in conjunction with the winds ramping up to near warning levels.

As for precipitation, well this is a clipper with a low track to the north. Warm advection wing will be short lived as it spends time saturating down into a warmer, drier near surface layer. On the backside, it will be weakly convectively unstable with wrap around showers. NBM depiction of a few hundreds is perfectly acceptable given the current uncertainties and overall nature of regimes precipitation potential.

Will continue to stick with the NBM in regards to the shallow amplitude track of this Colorado'esque type low Saturday. Still some wiggle room between deterministic guidance which is trending towards a north northwest to south southeast oriented deformation band of precipitation somewhere across the region. NBM is mainly presenting with snow initially Saturday morning with a transition associated with both a diurnal and advection trend of warm air to transition to rain for parts of the CWA before transitioning back to snow. Too far out to tell how far north this rain/snow line will wobble across the area.

The end of the weekend and start of next week continues to be very cold, with 850mb temperatures a standard deviation below climo, with the deterministic GFS more in line with GEFS values and the EC still down to 20 below at 850mb. NBM has trended warmer, through the 25th 75th percentiles range is still about 10 degrees and we can see the deterministic NBM currently falls closer to that 75th (warmer) range.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 615 AM CDT Wed Mar 11 2026

Terminals KABR,KATY,KPIR,KMBG

Fog remains at PIR/MBG with visibility jumping from MVFR to IFR just prior to 12Z, and ceilings down to 100ft at MBG. Expect improving conditions with fog becoming VFR at all locations by 18Z. Borderline VFR/MVFR have developed over northeastern SD and moved over ABR and are nearing ATY. Expect VFR conditions to dominate by 15z at ABR/ATY, with a couple hours of MVFR conditions returning (PROB30) with passing snow showers late this morning into mid-afternoon.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Fire Weather Watch from Thursday afternoon through Thursday evening for SDZ003>005-009-010-015>017-033>037-045-048-051.

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

High Wind Watch from Thursday evening through late Thursday night for SDZ006-018.

MN...None.