textproduct: Aberdeen

KEY MESSAGES

- Winds out of the south will gust 35 to 45 mph and relative humidity will fall into the 15 to 30 percent range. The strong winds and warm/dry conditions will combine to create very high to extreme grassland fire danger index values.

- There is a 30-70 percent chance of showers and thunderstorms Wednesday night into Thursday, mainly throughout central and north central South Dakota.

- Record or near record warm temperatures in the upper 80s to lower 90s are expected Wednesday.

- Strong sustained west winds 25 to 35 mph with gusts up to 50 mph are expected on Thursday. Windy conditions may last all the way through Friday into Friday night, especially along and north of U.S. Highway 212.

DISCUSSION

Issued at 159 AM CDT Tue Apr 21 2026

As an upper-level ridge moves over SD today, a surface high pressure will move over parts of northeastern SD and MN. This high pressure will cause the winds to shift to be from the southeast during the afternoon with gusts below 15 mph over northeastern SD and up to 20 mph over central SD. These weaker winds will help to lower fire weather concern over northeastern and parts of central SD today. Temperatures today will be 10-25 degrees warmer than normal, with highs in the 70s to low 80s. These temperatures will warm into Wednesday, getting to be 25-30 degrees warmer than normal, in the mid 80s to the low 90s, and could get close to breaking record temperatures in some areas.

Models are showing a low level jet setting up overnight into Wednesday morning, which will help to push warm, dry air into central and northeastern SD. Because of this, there is not a lot of RH recovery tonight especially over south central SD. This will help to drop the RH below 20% on Wednesday. A surface low starts to develop over MT Tuesday night into Wednesday, and as this low deepens, the pressure gradient over SD tightens. This tightening pressure gradient will help to increase wind speeds over central and northeastern SD Wednesday, with gusts getting up around 35-45 mph during the afternoon. A fire weather watch has been issued for portions of central SD due to these winds and RH values getting into Red Flag criteria. If any fire does ignite Wednesday, it could become difficult to control or suppress, even in areas where Red Flag criteria is not being reached.

Wednesday afternoon and overnight, the surface low starts to move east, with a cold front moving into SD during the night. There is a 30-70% chance for rain developing along the frontal boundary over central SD Wednesday evening and overnight. There is variability in the models as to the timing and how widespread the rain development will be, mostly due to the location of the swath of moisture aloft that moves in during this time. The models that have the moisture moving in over central SD have the development of rain and storms earlier in the evening and more widespread chances compared to models that have the moisture more to the east. Model soundings of the NAM and GFS show some elevated CAPE over central SD Wednesday night, which could help with the development of thunderstorms overnight. Models also show that is some shear above 35kts in the area when the higher CAPE values are, which could help any storms that develops to become severe and produce some strong wind gusts and hail. After midnight, the models depict CAPE decreasing and shear increasing as the cold front moves though, decreasing the chances for storms late Wednesday night into early Thursday morning.

As the surface low sits over ND Thursday, the tight pressure gradient over SD and the cold air pushing in will cause winds to increase through the day. Model ensembles show a 30-70% chance for winds to be above 45 mph west of the James River, with the highest chances west of the Missouri River. Some models have the surface low moving north quicker than others, which then causes the stronger wind speeds to be north of the area. A wind advisory will most likely be needed as the ensembles show less than a 30% chance for winds to get to or above 58 mph (high wind warning criteria). However, if the low moves out quicker, then a wind advisory will not be need as the winds will be weaker. Due to the precipitation chances Wednesday night and what could develop during the day Thursday, RH values will be higher than previous days. This will lower fire weather concerns Thursday, even with the strong winds. The cold air behind the front will also cool temperatures into the weekend over central and northeastern SD to be 5-15 degrees colder than normal.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1232 AM CDT Tue Apr 21 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Fire Weather Watch from Wednesday afternoon through Wednesday evening for SDZ015>018-033>037-045-048-051. MN...None.