textproduct: Aberdeen

KEY MESSAGES

- Heat advisory for the James Valley and points west Sunday. Temperatures in the 90s to around 100 degrees and dewpoints in the 60s resulting in heat index values around 100 to 105.

- Storms expected along a cold front late Sunday evening into early Monday. A Slight Risk (2 of 5) covers the northern tier counties of South Dakota, with a Marginal Risk (1 of 5) for the rest of the forecast area. Main threat is high winds. Not expecting a lot of moisture overall either.

- Heightened fire weather threat for Monday. Lightning starts from storms Monday morning possible. Northwest winds of 25 to 40 mph during the day, with drier air. Afternoon humidity down to around 20% across the Missouri Valley region, 30-40% across northeast South Dakota.

UPDATE

Issued at 621 PM CDT Sat Jul 18 2026

Aviation discussion updated below for the 00Z TAFs.

DISCUSSION

Issued at 112 PM CDT Sat Jul 18 2026

Precipitation wise, we have our ridge rider system for tomorrow, with elevated skinny CAPE in NAM BUFKIT profiles early in the day. The CAMS are latching onto some convection late morning coming in from the west so added some low POPs. The actual ridge rider late in the day has better potential for convection up in North Dakota with CAMS indicating this then migrates southeast into the CWA. Some also indicate convection also coming in from the west as well. NAM BUFKIT profiles likewise point to elevated skinny CAPE in moderate/high speed mid level flow (around 50kts). This suggest fast moving convection and overall not much rainfall potential, with a high wind threat.

NBM temperatures/humidity support a heat advisory for Sunday. NBM temperatures back into the 90s (northeast) to low 100s (central/north central). The wave to the north is helping advect a plume of elevated mixed air out of the west across at least central South Dakota with 700mb temperatures somewhere between +12 and +15C. Model dewpoints still only in the 60s east river and only upper 50s to near 60 west river so not "over the top" humid again and falls well in line with the trends we've seen over the last few of weeks. Even if NBM is overdone, will still be close enough for a heat advisory.

As we go into Monday, fire weather is the priority, with the lack of consistent moisture. Flagging vegetation and a lightning threat Sunday night/early Monday are then compounded by weak cold/dry air advection and northwest winds enhancing mixing. NAM BUFKIT mixed winds are up around 25-35kts.

Regarding smoke, there are multiple source regions to contend with that we will need to watch over the next several days, though the current surface high pressure does't have much smoke contained within or pivoting around. Focus for smoke shifts to Monday where a plume of elevated smoke from the Pacific Northwest/Western Canada starts to move into the region. There is a reflection at the surface at the tail end of the RAP/HRRR runs moving into North Dakota and as such can be supposed to continue towards CWA so something to watch.

Tuesday onwards, the upper pattern remains persistently a northwest flow regime resulting to closer to seasonal temperatures with low humidity. Low confidence on any precipitation chances with subtle waves mid-week and the wave that slips in under the ridge loop in around the upper high late Thursday. This is because much of this moisture is pivoting around the ridge taking the long way through the Intermountain West before kicking out into the Northern Plains.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 621 PM CDT Sat Jul 18 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. Only exception to this would be any TSRA that may affect KPIR/KMBG late tonight into early Sunday morning, perhaps with brief MVFR or even IFR VSBY. Will handle this threat with PROB30 groups for now until thunderstorm trends become a bit more clear later tonight.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory from 1 PM CDT /noon MDT/ to 9 PM CDT /8 PM MDT/ Sunday for SDZ003>006-009-010-015>018-033>037-045-048-051. MN...None.