textproduct: Aberdeen

KEY MESSAGES

- The first of two upcoming winter systems moves into the region this morning and continues through Thursday evening. Snow amounts of 4 to 8 inches is expected north of Highway 212, with the highest snow totals over the Leola Hills and the eastern slopes of the Sisseton Hills. South of Highway 212, 0.5 to 3" of snow is expected. A Winter Weather Advisory is in effect for all counties (except Jones, Lyman, and Buffalo) through Thursday.

- Freezing rain is possible late this evening through Thursday morning to parts of eastern South Dakota, particularly in the Watertown area. While confidence is low, portions of Day/Clark Counties and eastward through Grant/Deuel Counties may see upwards of a tenth of an inch of ice.

- Strong easterly winds will gust up to 25 to 35 miles per hour today, decreasing Thursday to gust up to 20 to 30 miles per hour. The combination of falling snow and strong winds will cause decreased visibility at times, as low as half a mile, today in particular. No whiteout/blizzard conditions anticipated.

- A second system will move in from the west Thursday night through Saturday bringing potential for freezing rain and additional snow. Impacts to travel are expected. Probability of 6" of snowfall or more is 60 to 95% along and northwest of a line from Eagle Butte to Sisseton, highest over north central SD. Probability of 8" or more of snowfall is 40 to 75% for this same area, highest over north central SD. Freezing rain will be possible Thursday night into Friday morning along and south of Highway 212.

UPDATE

Issued at 639 AM CDT Wed Apr 1 2026

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

DISCUSSION

Issued at 144 AM CDT Wed Apr 1 2026

The main concern will be the back to back systems that will bring accumulating snow, rain, and the potential for freezing rain. Temperatures during these events will play a key role in exact precipitation type along with where the freezing line ends up. The onset of precipitation with this first event will need to overcome dry air so precip may be spotty to begin with before the entire column saturates later on today and better forcing aloft. So low confidence on snow amounts and exact Ptype at this time. Once the system is upon us and we know exactly what is going on, several updates to the forecast may need be needed. So make sure to stay up to date!

Today Through Thursday Evening (System #1)

Both HREF along with GEFS/ENS are in agreement on the shortwave aloft, with the axis over the southwest US by 12Z this morning with the CWA on the downstream side of the trough in southwest flow. Through this evening, this shortwave will track eastward then northeast as it becomes more negatively tilted over the central Plains by Thursday morning. Not too much change in the models as the surface low will be over WY this morning where it will track southeast (and deepen) along the lee of the Rockies over Colorado by this evening. Models are somewhat consistent on the placement of this low, however, intensity does differ a bit, anywhere from 993 to 996mb (GEFS/CMC are the lowest). Through the overnight, this low will track eastward across southern NE/KS with the low over NE/KS/IA border by 12Z Thursday and continuing to track northeast and over MN/IA by 00Z Friday. GEFS is just ever so slightly more north and east with this low than ENS and a faster track. EC AI has a more southern track. Upper level support looks to really be from the 700mb low that will track across SD as the upper shortwave is displaced more south. In terms of moisture, PWAT's are about 2-3 standard deviation above climo with IVT about 2-3 above climo, however, this is more south of the CWA.

So precip wise, CAMs indicate rain and snow will move in over south central SD this morning with precipitation spreading east/northeast across the CWA through this afternoon as the CWA will be on the northeast/northern side of this low. It may take some time to initially start (or be spotty) as a few of the CAMs do show this, especially HRRR as there is dry air to overcome with this high pressure system and less forcing early. As it shifts east so will this dry air and we see better overall coverage in precip this evening. As temperatures do warm above freezing, precipitation will change to rain or a rain/snow mix. CAMS do vary on where this freezing line ends up. For example by 00Z, NAM/NamNest/RAP keep mainly snow over north central SD while rain or rain/snow is south of here. On the other hand, HiRESARW keeps temps cooler where mainly all snow is falling and really only rain over south central SD. HREF ensemble by this time show mainly all snow with the exception of south central SD with ptype being rain. As I will say several times, type will be temp dependent. Models do indicate a warm nose aloft (ENS quite more aggressive in this compared to GEFS)in which freezing rain will be possible over east central SD late this evening through Thursday morning between the warmer air/rain to our south and colder air/snow to our north, mainly Day/ Clark and eastward through Deuel County, as most of the CAMS indicate this along with HREF FRAM. As temperatures cool below freezing and we are then on the wrap around side of the low, snow will continue over the CWA through Thursday morning (and possible ongoing freezing rain over east central SD before the column cools) and exiting the far northeastern CWA by Thursday afternoon or so. So to reiterate, ptype will be HIGHLY dependent on exact temperatures as ENS is a bit cooler on temps than GEFS but only by a few degrees as highs today will range in the 30s to around 40. So PType could switch from rain to snow and vice versa, or a mix, very quickly. NBM 25-75th spread in 2m temps is about 2-4 degrees, increasing to 3-6 degrees this afternoon and evening with the highest spread over south central SD, and back to 2-4 overnight through Thursday. Also another caveat is the warmer temps lately so NBM is most likely running on a warm bias, so if temps are cooler than NBM,we could see more snow overall then rain. With collab from surrounding offices, we did lower highs for today/Thursday to match better with the HREF/global models. So overall low confidence on snowfall amounts and exact Ptype with this system.

So as mentioned the bulk of the precipitation will fall this evening through Thursday morning. The good news is we certainly need this moisture. GFS QPF amounts through 00Z Friday indicate 0.4 to 1.25" from Jones County northeastward through Marshall and eastward with amounts increasing the further east your go, with the highest amounts over east central SD. EC ranges from 0.6 to 0.9" for this same area. Canadian and NAM keep the higher QPF southeast of the CWA with the highest amounts of 0.4 to 0.6" over far east central SD. New run of NBM QPF lowers amounts west of the Mo River with amounts of 0.4 to 1" east of the Mo River, highest along the eastern slopes of the Coteau due to easterly winds/upslope flow. With temperatures hovering around freezing to a bit above, snow ratio will average around 10:1, a bit lower over the southern CWA. So latest snow totals actually decreased amounts given the possibility of warmer temps/more rain with deterministic amounts of 0.5 up to 8", lowest over south central and highest along eastern slopes of the Coteau and Leola Hills. Probability of 6" or more is about 50% for this area and 30% for 8" or more (mainly Leola Hills). The best case scenario (more rain/track is further south and east) 10th percentile amounts range from 0 to 3 inches. If temps are cooler and ptype is more snow or a more north and west track, 90th percentile will be 2 to 10 inches, lowest over south central SD and highest Leola Hills/Coteau. NBM is a bit lower than WPC at this time with both QPF/Snow totals on the order of an inch or two for any one location across the CWA. EC EFI does highlight values of 0.5 to 0.7 and SOT of zero right over the Leola Hills area for today with values of 0.6 to 0.8 east of the Mo River for Thursday, highest over eastern SD with a SOT of zero here.

With the snow totals, it has been quite warm over the past several weeks with zero frost depth meaning most of the ground is thawed. For at least the onset of the event, there may be some help from the warm ground in preventing snow from sticking on sidewalks and roadways until it cools further. There will also be plenty of time for compaction to limit the accumulations. So while upwards of 6-7" may fall to the ground, confidence is low on actually seeing these higher amounts and the associated impacts. Snow rates per HREF indicates up to a half inch per hour but only over north central SD later on this morning and again along the eastern slopes of the Coteau overnight, otherwise expect a tenth to quarter of an inch snowfall per hour. This also will help lessen any chances of quick accumulating snow on roadways. Ice amounts have really not changed ranging from 0.02 to potentially a tenth of an inch over east central SD, highest from Day/Clark and eastward through Grant/Deuel County. Again with the ground being warm, this may form on grassy surfaces, trees, cars, etc.

Luckily winds both at the surface and aloft will not be terribly windy with winds out of the east gusting between 25-35mph today and up to 30 mph Thursday. With a lack of any fresh snow on the ground, the latest run of the BLSN model shows drifting to isolated areas of blowing snow, which may reduce visibility at times, however, blizzard/whiteout conditions are not expected due to lower winds and lower snowfall rates, as mentioned. With the snow being wetter it will also cut down on being lofted. If traveling, please still use caution as WSSI indicates Minor Impacts over much of the CWA with moderate impacts along the eastern slopes of the Coteau and portions of Leola Hills per higher elevations and higher snow totals Today and Thursday.

No changes made to the headline as a Winter Weather Advisory is in effect for the entire CWA, with the exception of James, Lyman, and Buffalo Counties.

Early Friday through Saturday (System #2)

As the shortwave from the previous storm exits the region Thursday evening, a small and quick low amplitude ridge will build over the region early Friday morning before a large mid level low, centered over WY by 12Z Friday with the CWA returning to southwest flow ahead of this system. This closed low will track eastward across the Northern Plains through Saturday, with the CWA on the backside of this low by Saturday afternoon. Its surface low is very similar to this first system as it forms over WY with the area of low pressure dipping southward with a lee of the Rockies low forming Thursday night/Friday morning. It will then track across NE/KS and track northeast through IA/MN by Friday evening. ENS a bit further north with the track of the low where ENS-AI has the low over KS/OK/TX border by 12Z Friday and continuing with a more southerly and slower track. So confidence is low on track and intensity at this time. Enough support aloft with the 700mb low/shortwave will cause for a more widespread precip event late Thursday night/early Friday morning through Saturday afternoon. Rain, snow, and freezing rain looks likely as the models all really indicate this freezing rain potential Thursday night/Friday morning with the EC model being the most aggressive. Ensemble indicates quite the warm nose at 850mb (ranging from +1 to +4) at 850mb along and south of highway 212 early Friday morning, then northeastern SD/western MN before cooler air filters in on the backside of this low/wrap around (ptype changing to all snow as column cools) with surface temps below freezing.

NBM prob of freezing rain is about 20-40% over central SD early Friday morning transitioning to along and east of the Mo River 09Z- 12Z and James Valley and eastward 12-18Z before diminishing. Overall QPF amounts range from 0.4 to 0.8" per NBM, highest over central SD. As of now, the highest snow amounts look to be over north central SD with amounts diminishing south and southeast over the CWA. Probability of 6" is 60 to 95% from Eagle Butte through Sisseton and northwest. Prob of 8" is 40 to 75% for the same area, again highest over north central SD. Probability of 0.10" of ice is 40 to 60% along and south of HWY 212 and Coteau eastward. Just like the previous storm, SLR's will be on the lower end ranging from 8-11:1, increasing to around 14:1 Saturday morning as that colder air filters in. WSO probability of exceeding warning criteria coincides to where the higher snowfall is expected over north central SD with probability at 50-80%. No headlines have been issued yet for this second system as we will wait for this first system to pass. Headlines will be issued either next shift or the shift after.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 639 AM CDT Wed Apr 1 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for the moment early this morning remain at KABR/KATY/KPIR while KMBG is in MVFR CIGs and VSBYs in light snow. The trend this morning will be for MVFR/IFR conditions to take hold and prevail through the majority of this forecast cycle. Rain will mix with snow at times this afternoon at KABR/KATY/KPIR while KMBG sees more light snow through the day. KATY will have the best chance to see some light freezing rain late tonight into early Thursday. Easterly winds will gust up to 25-30 kts by mid to late morning at KPIR/KMBG and this afternoon at KABR/KATY terminals leading to reduced VSBYs at times, especially during phases of falling precipitation.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Winter Weather Advisory until 7 PM CDT Thursday for SDZ006>008- 011-018>023.

Winter Weather Advisory until 1 PM CDT /noon MDT/ Thursday for SDZ003>005-009-010-015>017-033>037.

MN...Winter Weather Advisory until 7 PM CDT Thursday for MNZ039-046.