textproduct: Aberdeen

KEY MESSAGES

- Rain chances return to portions of north central SD this morning before shifting into portions of northeastern SD and west central MN midday through this afternoon. Confidence is highest (50-85%) along and east of the Sisseton Hills where isolated thunderstorms are also possible.

- There is a Marginal Risk (level 1 out of 5) for isolated severe storms this afternoon east of Interstate 29 through west central MN. Main threats include 1" diameter hail and 60 mph wind gusts.

UPDATE

Issued at 1241 PM CDT Wed Oct 28 2026

Aviation discussion updated below for the 18Z TAFs.

UPDATE Issued at 1027 AM CDT Wed Oct 28 2026

Radar is showing light rain/sprinkles across portions of north central SD into the northern James valley. Made some adjustments to PoPs to better reflect radar trends. Also increased sky cover earlier this morning to account for the widespread stratus deck over the region. Models still suggest gradual erosion from west to east through the day as the front moves through the region. Still pockets of fog and lowered visibility across the CWA, and had earlier expanded mention of fog in the grids/forecast.

DISCUSSION

Issued at 155 AM CDT Wed Oct 28 2026

As of 1am temperatures are in the upper 30s to the upper 40s with winds mainly out of the southeast between 5-10mph. Satellite imagery continues to indicate low stratus surging northward east of the James River with KATY reporting a cloud deck of 600ft. Otherwise patchy to areas of fog continue to develop between the Missouri and James River with webcams indicating some of that being dense in areas. Have not issued a Fog Headline just yet as winds continue to keep things above criteria for now but will continue to monitor webcams and obs through the morning.

Our next shortwave continues to move in from the west and by 12Z, the axis of this wave will be over WY through CO with the region on the PVA side of it in southwest flow. At the surface the center of the low is forecast to be over west central SD with a weak trough connecting to a secondary low over northwestern KS. This is all within a large area of low pressure extending from a system in central Canada. On the northern side of the quasi stationary/warm front to start (mainly west to east across the center half of the state), CAMs do indicate a band(s)of elevated rain showers developing over WY/western SD and tracking northeast across portions of north central and northeastern SD into ND early this morning and more on the northern/northeast side of the low (as it tracks northeast) through the midday. By 18Z the center of the low will be near ND/SD/MN border with its fropa extending through eastern SD. With additional forcing from its shortwave and an 85-100kt jet aloft, dewpoints warming into the lower to mid 50s, and daytime heating, additional showers and even thunderstorms will develop ahead/along the front James Valley and eastward ~late morning/midday through the afternoon.

The resulting pops per NBM is 50-85% chance east of the James River with the highest pops Coteau and eastward. Coteau and eastward is really where HRRR/REFS does indicate spotty convective development (right along the front) over this area around ~17-18Z with these cells quickly moving into MN by ~22-23Z. NAMNest and RAP are a bit slower on the exit and a bit more westward extent of convection. NBM does a good job overall with coverage and timing due to a bit of a difference between the CAMS. Not too much SFC CAPE to work with (MUCAPE under 1000j/kg) but we do have the shear of 40-50kts and steep lapse rates of 6-7C/km Coteau and eastward between ~19-22Z this afternoon. So low cape high shear scenario. So for a few hours there will be enough energy for weak thunderstorms. Further east (far eastern SD/MN) if we can get enough vertical development into the cooler air aloft there could be the threat for an isolated cell or two to become severe(60 mph gusts/quarter hail), however, any more organized convection is forecast to remain further east into MN with better moisture/forcing. Very far portions of east central SD is within the 5% chance of severe weather for hail, per CSU ML guidance, which does back this up. WIth this threat, the SPC has expanded the Marginal Risk westward east of Interstate 29 through west central MN. Main threats include 1" diameter hail and 60 mph wind gusts. The last of the precip is forecast to exit by 00Z.

As the front track across the CWA winds will shift to the west/northwest behind it as drier air moves in aloft and high pressure filters in from the west/northwest. As winds become light tonight and ongoing moisture at the surface from the recent rains, plus radiational cooling, soundings once again do indicate this low level saturation below a strong inversion from the surface up to 950mb or so. REFS/HREF do indicate the formation of "low clouds" over the region overnight so lower confidence on if this is just low stratus forming or in fact fog. Probably of visibility at a 1/4th mile or less is 45-65% mainly across the James Valley and the Coteau per both HREF/REFS and once again NBM keeping low chances. So will watch the potential for this. Otherwise, high pressure keeps the area dry Thursday and Friday before another shortwave/low brings in additional chances of rain Friday night through Saturday night and again early next week.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1241 PM CDT Wed Oct 28 2026

Terminals KABR,KATY,KPIR,KMBG

An area of -TSRA/TSRA will affect the KATY region at the start of the TAF period, with brief MVFR VSBY, or even IFR VSBY if a heavier TSRA were to materialize. Otherwise, IFR/LIFR CIGs are gradually eroding from west to east and will continue to see these clouds scatter out through the afternoon, clearing KATY the latest it appears. Late tonight, patchy FG/BR is possible in the James/Big Sioux valleys and have inserted TEMPO mention for this.

ABR WATCHES/WARNINGS/ADVISORIES

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