textproduct: Aberdeen

KEY MESSAGES

- A Marginal Risk (level 1 out of 5) for severe weather is posted for parts of south central SD and the I-90 corridor today and tonight. The main threats will be large hail and damaging winds along and south of a line from Pierre to Brookings.

- A Marginal Risk (level 1 out of 5) for severe weather has been issued for most of central and northeast SD on Wednesday and Wednesday night. Large hail and damaging winds will be the main threats.

UPDATE

Issued at 550 AM CDT Tue Aug 18 2026

Updated discussion for the 12Z TAFs below.

DISCUSSION

Issued at 254 AM CDT Tue Aug 18 2026

As of 2 AM CDT this morning, parts of our forecast area continue to see a couple of storms tracking southeast across parts of south central SD. These have been associated with mid level shortwave energy and an upper jet streak working out of the Northern High Plains into the Dakotas along with a weak sfc trough and an incoming cold front sagging south across ND. Current temperatures generally range between 60-70 degrees with light winds.

The main forecast challenge during the next few days will continue to revolve around scattered storm chances as a northwesterly flow aloft pattern remains persistent across the Northern Plains. Within this flow, periodic shots of shortwave trough energy will rotate across the region through mid week maintaining the active convective pattern. What ends up being leftover from early morning storms across parts of central and southeast SD along with shower activity filling in across parts of northeast SD and west central MN will exit the forecast area by mid morning. Dry conditions are then expected to set up for the rest of the day as a cold front shifts south across central and southern SD. This will help focus the better instability across southern sections of the state into NE during peak heating this afternoon. However, parts of south central SD and the I-90 corridor will still see MLCAPE values of 1000-2000 J/kg develop. A 100+ kt jet streak setting up across SD should help provide adequate deep layer shear of 40-50 kts. This will be within a post-frontal environment and the early morning convection that moved through that area will have sent in motion an outflow boundary farther south into NE and KS by this afternoon and evening. Nevertheless, given that more shortwave energy will work out of the Northern High Plains across parts of western SD, a couple of strong to severe storms cannot be ruled out this evening into early Wednesday. SPC has maintained a Marginal Risk (level 1 of 5) for severe weather across south central SD. Large hail to 1 inch in diameter and damaging winds up to 60 mph will be the main threats.

Sfc high pressure will center itself across parts of ND during the day today and into eastern SD/western MN tonight into Wednesday morning. This will provide for a cooler overnight with temperatures falling back into the 50s. As the high slips off to our south and east during the day Wednesday, return flow will set up across western and central SD by the afternoon. During this time, sfc low pressure along with a pseudo warm front or sfc trough will work back to the north and northeast Wednesday afternoon and Wednesday night. Daytime heating will lead to MLCAPE values of 1500-2500 J/kg with deep layer shear values of 35 kts. Another round of showers and storms are expected to develop in the afternoon and evening as another shortwave trough is progged to move through the region. A few storms could turn severe with large hail up to 1 inch in diameter and damaging winds up to 60 mph. SPC has posted a Marginal Risk (level 1 of 5) for severe weather for central and northeast SD.

The outlook for the end of the week into the weekend will essentially feature more of the same. An upper ridge across the western CONUS will amplify as another sfc trough tracks southeast across the eastern Dakotas and western MN on Thursday. Daytime heating will lead to another unstable environment with increasing instability, adequate deep layer shear and steep lapse rates. It remains to be seen when and where any severe convection will set up but our eastern zones will be in a more favorable window for some. High pressure building southeast into the region Friday into Saturday looks to give us a break from storms. Temperatures will cool a bit back just below normal and humidity values will return to more comfortable ranges.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 550 AM CDT Tue Aug 18 2026

Terminals KABR,KATY,KPIR,KMBG

VFR cigs are forecast through the end of the TAF period. A cold front will continue to sag southward across the state this morning with winds mainly out of the north and northeast by the late morning. Scattered showers and thunderstorms will move back into the region late this afternoon or evening and continue through the overnight hours, mainly over central SD, possibly affecting KPIR. Due to low confidence between the models in timing and track of potential storms, left out of the TAFs for now. A few storms could potentially become severe over portions of south central SD with the main threats being quarter size hail and 60 mph wind gusts. Sub VFR cigs are possible with any stronger storm or heavy rains.

ABR WATCHES/WARNINGS/ADVISORIES

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