textproduct: Aberdeen

KEY MESSAGES

- Hot and humid again Friday, even with a frontal boundary shifting south winds to northerly. Heat index values Friday in the mid to upper 90s, possibly 100F.

- Storm chances (20-40%) for Sunday with a wave that signals a change in the pattern to closer to average temperatures.

DISCUSSION

Issued at 102 PM CDT Thu Jul 16 2026

Temperatures/dewpoints are well aligned with NBM though dewpoints started out a little higher in comparison. Like yesterday, still expecting they will effectively mixed out with the ample sunshine/warm temps and a lack of recent soil moisture. Low level flow has become more southerly through the morning, increasing to around 15-25mph. A weak boundary crosses the region overnight into Friday and while there is a change in winds, little change in actual airmass with temperatures/dewpoints maintaining the current status quo.

The upper level pattern shows the continued trend for the upper ridge across the CONUS to gradually amplify out west, with a trough intensifying over the eastern CONUS, giving us increasing flow out of the northwest. This regime will set us up with a northwest flow wave that crosses through the Western Lakes region Friday night. The ridge re-amplifies in the wake of this wave, however is appears a pair of ridge-riders follow for Saturday and Sunday. Those two systems give us our precipitation chances, though the first appears mainly as a upper/mid level deck above 14kft with a deep dry subcloud layer.

The initial wave's main impact for our area appears to be the high pressure that follows, nosing down into the Dakotas it provides for slightly more average temperatures and a slight downward trend in humidity. Easterly mixed winds only top out around 5 to 15kts, so while afternoon humidity tanks to around 20 to 30% west of the James valley, winds fall short of Red Flag.

Regarding smoke, an extension of the plume to the east had backed into western Minnesota this morning, with Morris down to 1/2 mile and the webcam west of Herman on the Traverse MN county line indicating low visibility as well. HRRR shows this will be at its worst through late morning, but as surface winds better organize to southerly out ahead of a surface trough, near surface plume both mixes out and shifts northwards. This is probably not the last we will see in regards to surface smoke, as surface high pressure out of Canada crosses from the Dakotas to the Western Lakes region over the weekend. Flow around the high could eventually pivot smoke back into the region, though at this point its uncertain as the fires in southwest Ontario/NE Minnesota is a source region that is kind of unusual to have a direct fetch from.

For fire weather concerns, again its pretty marginal through the next few days as we continue to see this hot and dry weather stress vegetation. Uncertain how widespread the moisture will be Sunday and as such not factoring it into any sort of relief. Thus, looking at potential days in which we'll have lower humidity and higher wind speeds - attention is drawn to Monday where another front moves through. A tighter gradient and slightly stronger cold advection for Monday means more winds. GFS mixed winds are only about 20kts, however NBM afternoon humidity is widespread down around 20% along and west of the James Valley. Fire Danger is getting into the High category across much of north central South Dakota Monday.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 102 PM CDT Thu Jul 16 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for all terminals. South winds will become northerly with the passage of a weak front.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory until 10 PM CDT /9 PM MDT/ this evening for SDZ003>006-009-010-015>018-033>037-045-048-051. MN...None.