textproduct: Bismarck

KEY MESSAGES

- Hot and smoky conditions continue today. High temperatures and heat index values could reach 100 degrees across much of the western half of the state.

- Isolated to scattered severe thunderstorms are possible this afternoon into tonight. Potential hazards include damaging winds up to 70 mph and hail as large as ping pong balls.

- High chances (60 to 90 percent) for scattered thunderstorms across southern North Dakota on Thursday. A few storms could be severe and produce locally heavy rainfall.

- Cooler on Thursday, then becoming hot once again through the weekend.

DISCUSSION

Issued at 530 AM CDT Wed Jul 29 2026

Upper level ridge extends from the Southern Rockies through Northern High Plains early this morning. North Dakota lies between high pressure over Wisconsin and a surface trough over central Montana. Ground-truth reports indicate smoke remains present in the near- surface layer across northern North Dakota, and on its own has been reducing visibility as low as 5 miles. Particulates from the smoke have provided sufficient condensation nuclei for patchy fog to develop in low-lying areas of north central North Dakota early this morning. The fog is not expected to be nearly as impactful as 24 hours ago, but there have been brief observations of quarter mile visibility from western Bottineau to northern Ward Counties. Any fog should burn off by mid morning, but near-surface smoke could persist through the day, if not longer. A mention of patchy smoke was maintained in the forecast through this afternoon, with confidence beyond the afternoon remaining low.

Today is expected to be the hottest day of the work week as the thermal ridge once again points into the western Dakotas. The NBM suspiciously increased its 50th percentile high temperature projections by a few to several degrees, which seems inconsistent with all other previous and current guidance. We trended our high temperature forecast closer to the maximum of NBM/HRRR hourly guidance, which gives a more reasonable forecast of around 95 to 100 across most of western and central North Dakota, and is much more consistent with previous forecasts over the past few days that had shown little to no change. The hottest forecast temperatures and heat indices are focused over the Missouri River Valley, and also extend south to the I-94 corridor west of the river. A Heat Advisory has been issued for these areas, in effect from noon to 8 PM CDT.

Forecast confidence in convective evolution and intensity this afternoon through tonight is not that high. An inverted lee trough is forecast along the ND/MT by mid afternoon. CAMs are consistent that there will be enough forcing from surface convergence, low level frontogenesis, and weak shortwave energy ejecting off the Northern Rockies to initiate deep moist convection along the surface boundary by mid to late afternoon. Despite hot temperatures and dewpoints only favored to mix down into the lower to mid 50s, model soundings reveal a skinny CAPE profile with very high LFCs at around 600 mb. Differences in mid to late afternoon buoyancy projections range from as high as 2500 J/kg SBCAPE in the RAP to as low as 500 J/kg in the HREF mean MUCAPE. Think closer to 1000 J/kg is the most likely outcome, which is still sufficient for severe storms but lower than previously anticipated. The deep layer shear forecast has also weakened in the most recent model guidance, with only around 25- 35 kts in the 0-6 km layer, highest in northwest North Dakota. Dry- air entrainment and residual CIN also remain a concern for convective development and sustainment. These limiting factors are seemingly reflected in CAMs' UH output, with HREF neighborhood probabilities of UH greater than 75 m^2/s^2 only reaching 10 percent, and only that high in northwest and north central North Dakota. Previous forecast thinking on a favored storm mode of linear north to discrete south remains valid as far as vector orientation is concerned, but CAMs' reflectivity is more indicative of a mixed/cluster mode with splitting supercells (which modeled hodographs do confirm is a possible outcome). Because of the inverted-v thermodynamic profile, damaging wind is the most likely severe hazard. Large hail is still possible with discrete storms, but the decrease of forecast CAPE and shear has prompted us to lower our most likely maximum hail size forecast to ping pong balls. The tornado risk in northwest North Dakota, which was already low to begin with, appears to have lowered even further. But because there is still potential for a triple-point axis, and model hodographs at Crosby have actually switched from crosswise to streamwise vorticity in the 0-1 km layer, will maintain the mention of a possible tornado in far northwest North Dakota for now.

CAMs remain inconsistent on convective evolution into central North Dakota during the overnight hours. The risk for severe storms is likely to end by around midnight, but one to a few clusters of storms could persist through the night. On Thursday, a deeper shortwave is forecast to cross the Northern Plains and produce widespread showers and thunderstorms, especially across the southern half of the state. Enough CAPE and shear may be present to support isolated severe storms, but convection seems likely to remain elevated. The greatest concern from thunderstorms on Thursday may actually be heavy rainfall, with anomalously high precipitable water, high deep layer RH, and the potential for multiple rounds of storms at any given location.

Increased cloud cover is likely to render Thursday the coolest day of the week, for which forecast highs have fallen into the upper 70s to upper 80s. But it could still be very humid on Thursday with forecast dewpoints in the 60s west to 70s east. The upper ridge is forecast to rebound over the western CONUS and pivot back over the Northern Plains Friday through the weekend, allowing temperatures to heat back up to near 100 in the west on Saturday and central on Sunday. A low-amplitude wave rounding the top of the ridge could bring a few showers and thunderstorms to western North Dakota Friday evening. Ensemble guidance remains confident on a potent shortwave ejecting into the Canadian prairie provinces on Sunday, driving a cold front through the region late Sunday into Monday. Windy and hot conditions ahead of the cold front could introduce fire weather concerns for the weekend, particularly on Sunday. The passage of the cold front should finally provide relief from the heat through at least the middle of next week, with highs in the 70s and 80s.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 530 AM CDT Wed Jul 29 2026

Smoke from distant wildfires will likely persist through the forecast period. MVFR visibility cannot be ruled out from time to time, but VFR conditions should mostly prevail. Scattered showers and thunderstorms are forecast to develop in western North Dakota late this afternoon and could spread eastward into the evening and overnight hours. A few storms could be severe with damaging wind gusts. Winds are otherwise expected to be southerly at around 10-15 kts today.

BIS WATCHES/WARNINGS/ADVISORIES

Heat Advisory from noon CDT /11 AM MDT/ today to 8 PM CDT /7 PM MDT/ this evening for NDZ009-010-017>020-031>033-035-041- 042-046-057>062.