textproduct: Bismarck

KEY MESSAGES

- Hot conditions will continue through at least the middle of the week, with highs mostly around 90 to 100.

- Smoke from distant wildfires will continue to make the sky hazy and reduce surface visibility early this week.

- An isolated strong to severe thunderstorm could enter far southwest North Dakota this afternoon and early evening, with the main hazard being wind gusts up to 60 mph.

- Medium chances (30 to 60 percent) for showers and thunderstorms Wednesday afternoon through Thursday. A few storms could be severe in western North Dakota Wednesday afternoon and evening.

DISCUSSION

Issued at 438 AM CDT Mon Jul 27 2026

An amplified upper level ridge persists from the Southern Rockies through the Northern High Plains early this morning, while a surface ridge extends from Saskatchewan into western North Dakota. The upper ridge is forecast to remain nearly stationary through today, although a mid level shortwave currently located between Yellowstone and the Great Salt Lake will eject towards the Black Hills later today. This will induce lee troughing from the Black Hills into southwest North Dakota while the surface ridge slides eastward into central North Dakota. With all this occurring underneath the right entrance region of an upper jet streak, enough forcing should be present to initiate storms along the higher terrain of northeast Wyoming/southeast Montana this afternoon, with east- northeastward propagation. A consensus of CAMs clips the southwest corner of the state with this activity between mid afternoon and early evening. Forecast confidence is high in effective bulk shear around 35-40 kts, but there is greater uncertainty in buoyancy. CAPE could first be regulated by the degree of moisture advection between the lee trough and downstream surface ridge, then by the strength of boundary layer mixing. Ensemble averaged CAPE is generally no greater than 1000 J/kg, and a lingering warm nose aloft could keep convection elevated. The main hazard with any storm entering far southwest North Dakota later today is wind gusts, possibly as strong as 60 mph. The SPC Day 1 Convective Outlook does clip far southwest North Dakota with a Conditional Intensity Group level 1 for damaging winds as high as 75 mph, but given the location and footprint of the pool of buoyancy, think significant winds are much more likely to be confined south of the stateline. Outside of far southwest North Dakota, some CAMs have been simulating a variety of shower or thunderstorm activity in other parts of the state throughout the day. But with forecast cloud bases closer to 15 kft, not expecting anything beyond just a few sprinkles at the surface, with most of what develops being virga.

Today will be a few to several degrees cooler for most locations. The projected thickness of smoke aloft introduces uncertainty into the high temperature forecast for today. Given observed conditions both overhead and upstream last evening, and little to no change in HRRR modeled vertically-integrated smoke concentrations from then through this evening, our high temperature forecast for today is just slightly cooler than the NBM, with mid and upper 80s far north to mid 90s southwest and south central. Near-surface smoke concentrations are also projected to be similar to what arrived yesterday, so reduced visibility cannot be ruled out. The mention of smoke in the forecast has been extended through tonight.

The upper level ridge is projected to more or less remain in place through Wednesday. The forecast for Tuesday is similar to that for today, with slightly warmer high temperatures around 90 to 100, lingering smoke both at the surface and aloft, and low probabilities (less than 20 percent) for isolated afternoon and evening thunderstorms across southern North Dakota. Synoptic scale forcing looks very weak on Tuesday, so any convection that does initiate would likely be on account of convective temperatures being breached. Slightly higher CAPE is forecast on Tuesday with deep layer shear around 30 kts, so a stronger storm cannot be ruled out. On Wednesday, the thermal ridge axis is forecast to pivot into North Dakota ahead of stronger shortwave energy ejecting from the Great Basin. Widespread high temperatures and maximum heat indices around 100 are in the forecast for Wednesday. Convection could initiate near a lee surface trough along the ND/MT border Wednesday afternoon, and should become more widespread in western North Dakota with the arrival of the shortwave Wednesday evening, spreading into central North Dakota overnight. Forecast confidence in both CAPE and shear remains low, but a Marginal Risk was introduced to western North Dakota for the Day 3 Convective Outlook, and CSU machine learning guidance also highlights low severe storm probabilities on Wednesday.

The eastward progression of the shortwave could be slow enough to keep showers and thunderstorms in central and eastern North Dakota on Thursday. After a slight cool down to highs in the mid 80s to mid 90s for Thursday and Friday as a result of the downstream shortwave digging into the Great Lakes and Ohio River Valley, the upper level ridge is forecast to rebound and become even more amplified from the Desert Southwest to the Canadian Prairie this weekend. Ensemble guidance projects the thermal ridge axis to be over the Northern High Plains on Sunday, which once again has medium chances for temperatures exceeding 100 degrees. A major pattern shift could finally be on the way early next week as ensemble guidance favors deep troughing over southern Canada.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 438 AM CDT Mon Jul 27 2026

Smoke from distant wildfires is expected to remain thick aloft through the forecast period. Surface visibility restrictions from the smoke are less certain, but MVFR could return to parts of the region today. Aside from the smoke, VFR conditions are expected through the forecast period. A few showers and thunderstorms are possible in far southwest North Dakota throughout the day, with virga more likely to the north and east. Some gusty winds could be associated with showers or storms. Otherwise, winds should remain around 10 kts or less with varying directions.

BIS WATCHES/WARNINGS/ADVISORIES

None.