textproduct: Aberdeen

KEY MESSAGES

- Dry conditions expected today before a weak disturbance tracks over the region Wednesday morning into the afternoon, bringing the opportunity for isolated to scattered showers and weak thunderstorms.

- Another round of rainfall is expected late Thursday through Friday. The highest accumulations are expected over eastern South Dakota, where probability to see an inch of rain or more ranges from 40-60%.

DISCUSSION

Issued at 144 PM CDT Tue Sep 15 2026

As high pressure keeps moving over central and northeastern SD today, it will help to keep showers and storm chances out through tonight. Skies will be staying mostly clear through the remainder of the day and into the night, which will help the temperatures tonight drop into the low 40s to low 50s. Humidity will stay fairly high through the night, and with light winds and fairly saturated soils from yesterday's rain, there could be patchy areas of fog that develop over areas east of the Missouri River. This fog will be more localized and should not go below a mile in visibility.

An upper-level shortwave will be moving over SD early Wednesday morning into the afternoon. This will help some stronger winds aloft to move in central SD tonight. As this low level jet moves over, some warm, moist air moving into central SD will start to develop some isolated to scattered showers and storms early Wednesday morning. As the low level jet moves east through the morning into the afternoon, it will continue to cause these scattered showers and storms over central and northeastern SD. These showers and storms will be fairly weak and will not become severe. Rain amounts from these showers and storms look to not be a lot, with only a 20-40% chance for 0.1 inch or more rain to fall mainly over north central SD.

The low-level jet will stick around over central SD through the morning and into the early afternoon. While early in the morning the lapse rates will be weaker and it will be harder for the stronger winds to mix down, through the morning and into the afternoon the lapse rates will increase, causing stronger winds to get to the surface over central SD. Ensembles show a 40-80% chance for winds to gust up around and over 35 mph over areas west of the Missouri River, and a 30-50% chance for winds to gust up around and over 40 mph over Corson and Dewey counties. These winds speeds are strong but they do stay below wind advisory criteria for now. Relative humidity values will stay around and above 50% in the locations and around the time of the strongest winds. This helps to keep the fire weather concerns lower for Wednesday.

The next chance for accumulating precipitation will start Thursday afternoon through Friday as a warm front and surface low pressure moves in and towards central and northeastern SD. Models are still varying the location of this low and frontal boundary as well as dry air moving into northeastern SD Thursday evening into Friday. This causes different outcomes in the location and timing of showers and storms moving through SD. A majority of the models are showing the precipitation moving through mainly south central SD to the east over portions of east central and southeastern SD, with the bulk of the rain occurring over eastern SD. However, some models have the area of rain more to the north or to the south, leading to lower confidence in the location and some of the timing of the showers and storms. Depending on where the showers and storms end up, as well as how much dry air mixes in, the rainfall amounts vary as well. Some models have chances for 1-3 inches over central and northeastern SD, with the highest amounts over eastern SD. However, other models keep the values lower, with 0.5-1 inch of rain possible. This is something to keep an eye on as more model runs come to more of an agreement. Either way, there is currently a marginal to slight Excessive Rainfall Outlook for portions of central and northeastern SD, with the highest chances of flooding potential to the southeast of the area.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1220 PM CDT Tue Sep 15 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue through the day and into the night. Some afternoon cumulus clouds are starting to develop over portions of northern South Dakota which could lower the cloud bases to at times during the afternoon to be between 3500 to 7500 feet, though there should only be a few clouds in the sky so there will not be low ceilings. Conditions should stay VFR into the morning for most terminals, though with higher humidity and lower wind speeds, there could be some patchy spots of fog that could develop during the early Wednesday morning over KATY and KABR that could reduce visibilities slightly. Northwesterly winds will start to turn this evening to become more easterly overnight then southeasterly during the day Wednesday. The winds will pick up Wednesday morning into the afternoon and be gusting up around 30 mph over KPIR and KMBG and up around 20 to 25 mph over KABR and KATY.

ABR WATCHES/WARNINGS/ADVISORIES

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