textproduct: Aberdeen

KEY MESSAGES

- Rain today across central South Dakota. Probability of exceeding 2" up to 60% across Jones/Lyman counties. Potential rainfall amounts drop off dramatically north and east with little if any expected for northeast SD/western MN.

- A fast moving system Monday night/Tuesday morning with a 40-70% chance of > 0.25". Severe weather is not anticipated.

- Temperatures remain near to slightly below normal through next week. Coolest day being today at 5 to 20 degrees below normal. More seasonal temps and humidity late week/next weekend.

UPDATE

Issued at 607 AM CDT Sun Jun 21 2026

UPDATE for TAF discussion below.

DISCUSSION

Issued at 101 AM CDT Sun Jun 21 2026

Not much overall change with the system today, with main placement of the QPF bullseye still over central South Dakota. HREF/NBM have a peak 2+" along the I90 corridor in central/south central South Dakota, with a gradient to the northeast and less than a 1/4" for Aberdeen/Watertown. That said, deterministic forecast is a little lower at 1 to 1.5" though same bullseye placement lending continued high confidence in regards to drought relief across central South Dakota. To the north, Mobridge area, looking at a drop in the deterministic forecast down to about 0.1" which is close to the HREF mean and well below the deterministic NBM which still sits just above 1/2". Thus, a little uncertain across the north central with a gradient from north to south. Same thing as we transition into northeast South Dakota, with a gradient that continues to drop off to near nothing by the time you get to Aberdeen/Watertown as mentioned earlier.

Looking to the next wave that follows close behind. Still looking at a rapid frontal progression during the overnight hours Monday/Tuesday morning which will limit rainfall amounts. Mean NBM is a tenth or two, with our deterministic forecast running just a tad higher. NAM BUFKIT profiles depict skinny CAPE on the order of 100- 200j/kg and limited shear below 400mb.

Thereafter we remain in a west to northwest flow regime. While not much low level moisture, mid level cool air will result in daytime driven destabilization with the NAM showing some CAPE under a unidirectional shear environment, not unlike the last couple of days of convective activity. NBM lingers POPs across the far east Tuesday afternoon. Likely a similar situation for Wednesday afternoon though more northerly flow as the surface high shifts to to the eastern Dakotas/western Minnesota. Return flow on the backside of the high takes over for late Thursday/Friday. Mid level warm advection aided convection shows up in NBM POPs Friday morning.

Looking way way out, late weekend/early next week we see a trough set up over the Northern Rockies. Now established southerly flow across the Plains taps into Gulf moisture which has been pooling in the souther/central Plains. We're starting to see NBM reflect this in 60+ dewpoints. The trajectory of the system is still to be resolved given how far out, but it should be noted that there is fairly good agreement in deterministic models at this point. It also should be noted that this storm trajectory has the potential to draw in some very warm air aloft. The GFS has +17C at 700mb, though the GEFS mean at this point is only +10C and barely registers as a standard deviation above climo. This GEFS mean is underdone this far out given the spread in ensemble outcomes but is telling in that at a minimum when this system progresses though a 700mb temperature cap will need to be reckoned with when assessing any severe weather potential.

ABR WATCHES/WARNINGS/ADVISORIES

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