textproduct: Bismarck

KEY MESSAGES

- Isolated to scattered severe thunderstorms are possible this afternoon and evening. Expected hazards include hail as large as 2 inches in diameter and damaging winds up to 70 mph, with a tornado possible.

- Hot and humid today, with high temperatures and heat index values around 95 to 100.

- Windy on Monday, with near-critical to possibly critical fire weather conditions in the southwest and south central North Dakota.

- Cooler on Tuesday, then becoming hot once again by the end of the week.

DISCUSSION

Issued at 235 PM CDT Sun Jul 19 2026

Currently there is near zonal flow over the Northern Plains as the large ridge that is mostly over the CONUS has a flat top now. An upper level low near Vancouver is creating a slight southwest tilt in the flow over the northern Rockies and North Dakota. This, along with some speed shear at the mid levels is creating our severe storm risk today. At the surface there is weak low pressure influence in the state, and a surface trough/front that has moved east into western North Dakota. Little to no clouds are currently floating around, except some cumulus forming on the boundary in the southwest.

As the afternoon progresses, strong diurnal surface heating and mixing will bring temperatures near 100 degrees across the west and south. There is generally a large cap across most of the severe risk area, however the forecast high temperatures are near or above the convective temp to start surface based storms. Otherwise storms may stay elevated like previously forecasted. Model soundings across the area continue to show a strong dry level near the surface shown by large invert V soundings. Looking at DCAPE across the west and central, values are well over 1000 J/kg. This lower dry air is a big limiting factor for surface based storms to form, leading to the idea that these will likely be elevated. MUCAPE is currently elevated and is 1000-2000 J/kg. The forecast CAPE axis by 00z is north to south in the James River Valley with values up to 3000 J/kg. The shear vector is currently straight off the boundary leading to isolated (possibly supercells) forming, however with the straighter hodographs splitting storms will be a very real thing. Eventually the CAMs have these storms forming into a line as the boundary becomes more parallel with the shear vectors. This will be when 70 to 80 mph winds are possible as the dry air surges the wind towards the surface.

Timing looks to be around 22/23z somewhere west of Highway 83. When these isolated cells then hit the bigger CAPE to the east, and the boundary is less straight on with the shear vectors is when it would go linear around 8pm (somewhere east of Highway 83). With the high CAPE and shear values around 45kts, we are still advertising 2 inch hail, which would happen when storms are isolated still. Since storms could be splitting and possibly reforming on outflow boundaries, there is a low brief tornado risk when these storms interact with these boundaries. Based on the CAMs these storms should be in the Red River Valley by midnight.

Behind all these storms is a surface cold front that will move into the northwest corner of the state by midnight. Unfortunately this will carry near surface smoke with it. Expected a hazy and smokey day Monday whether the smoke stays elevated or mixes down. The thickest surface smoke is forecast to move through the southwest half of the state overnight, but may linger in the post frontal air through the day. Temperatures from the cold front will generally only be cooler in the far north around 80 degrees with the rest of the area still in the 90s. As with most cold fronts, northwest winds will gust 20 to 40 mph, especially in the central and James River Valley. There are some fire weather concerns in the southwest and south central but the wildland grasses just aren't dry enough to be concerned with the large uncontrollable fires that the Red Flag Warning is intended for. We opted to just stick with the near to possibly critical wording without any products. There is also a low chance of isolated rain showers in the north Monday.

The rest of the week will restart the extreme warming trend as another large ridge builds back in. By next weekend temperatures will be back into the 100s, with likely heat headlines.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1236 PM CDT Sun Jul 19 2026

Mostly VFR through the period. This evening and early tonight severe thunderstorms are possible, and may produce large hail and erratic and gusty winds. A PROB30 was used where there is higher confidence. Near surface smoke is likely tonight through Monday carried in by a cold front, reducing VIS to at least 6SM. Winds this afternoon will be mostly southerly before turning to the northwest overnight. Monday will be breezy with winds gusting near 40kts in the afternoon.

BIS WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 9 PM CDT /8 PM MDT/ this evening for NDZ017>020-022-023-025-031>033-035>037-040>044-046>048-050-051- 057>062.