textproduct: Bismarck

KEY MESSAGES

- One more day of very hot conditions across southern North Dakota, with heat index values and temperatures around 95 to 100 this afternoon.

- Low chances (10 to 30 percent) for isolated thunderstorms from south central North Dakota to the Turtle Mountains late this afternoon and evening. A strong to severe storm cannot be ruled out.

- Patchy fog is possible in northwest North Dakota tonight through mid Friday morning.

- Slightly cooler Friday and Saturday, then hot again for most areas on Sunday. Temperatures are then favored to fall closer to normal next week, with forecast highs mostly in the 80s.

UPDATE

Issued at 1240 PM CDT Thu Jul 16 2026

Low stratus and fog continues to lift across northwestern North Dakota at the time of this mid day update. With calm winds and a near surface inversion again evident in model soundings, have opted to include patchy fog across the northwest tonight through mid Friday morning. Otherwise, the forecast remains on track at this time.

UPDATE Issued at 1127 AM CDT Thu Jul 16 2026

Quiet weather is found across western and central North Dakota at the time of this late morning update. Isolated weak reflectivities linger across portions of the far north central, though dry near surface conditions have helped limit the amount of precipitation that has reached the ground. Patchy fog and low ceilings linger across portions of the far northwest, though these are expected to lift over the next hour or so. No major adjustments were made to the forecast this at this time, as it remains broadly on track.

UPDATE Issued at 652 AM CDT Thu Jul 16 2026

Low stratus and fog have intruded far northwest North Dakota early this morning. Satellite and webcams show the fog to mainly be impacting Divide County, where a Special Weather Statement has been issued. The fog should lift by around 10 AM CDT. No other forecast adjustments were needed for this update. A few stray showers continue to propagate through far north central North Dakota.

DISCUSSION

Issued at 421 AM CDT Thu Jul 16 2026

Broad upper level ridging still prevails over the Northern Plains this morning, with a 500 mb high analyzed from the Dakotas to the Ohio River Valley. A mid level shortwave rounding the top of the ridge is responsible for isolated to scattered showers across northern North Dakota early this morning, with more persistent and relatively stronger convection remaining north of the Canadian border. Still cannot rule out a thunderstorm or two in northern North Dakota this morning, but MUCAPE is vanishing. At the surface, low pressure is analyzed just north of the Black Hills, with an inverted trough extending northward through western North Dakota.

The inverted trough is forecast to pivot into a positive tilt through this afternoon, with a high-resolution ensemble mean location from Sioux County to the Turtle Mountains/Devils Lake Basin by early evening. Also this afternoon, a mid level shortwave is forecast to deepen underneath the upper ridge over southern Saskatchewan and Manitoba. This setup introduces a conditional threat for isolated strong to severe thunderstorms along the inverted trough late this afternoon and evening. The highest chances for convective initiation are closer to the Turtle Mountains where a deeper layer of forcing should be present, but surface wind convergence and low level moisture flux convergence are projected to be stronger farther south. The big questions of course are whether there will be sufficient forcing to overcome a capping inversion, and how much erosion of the cap can occur from diurnal heating alone underneath neutral mid level height tendencies. The environment is forecast to be more favorable for stronger convection farther north, with around 2000-3000 J/kg MLCAPE and up to 30 kts of deep layer shear. Shear, deep layer wind, and anvil level wind vectors all strongly favor a discrete storm mode with near-perpenedicular orientation to the inverted trough. Forecast hodographs show enough curvature and length to support supercells in north central/northeast North Dakota, but they are shorter and more chaotic farther south. The main expected hazard from any storm that develops would be large hail, but the probability of CI occurring along the inverted trough is still only around 10 percent south to 30 percent north. The scenario of isolated storms that may or may not realize the maximum available buoyancy and shear is well-depicted by the current suite of CAMs. If storms do develop, they should quickly diminish, or at the very least weaken substantially, after sunset.

One more day of impactful heat is anticipated across the southern half of the state, but moreso focused on south central North Dakota where afternoon temperatures along the inverted trough could reach 100. Afternoon dewpoints mostly in the 60s push the maximum heat index forecast a couple degrees higher than the maximum temperature forecast at most locations. Interestingly, the maximum wet-bulb globe temperature risk takes a notable jump upward from yesterday, with the Extreme category across much of south central North Dakota and into the northern James River Valley, and the High Category is widespread across all but far northern parts of the state. A Heat Advisory remains in effect for all counties south of Highway 2 until 10 PM CDT this evening.

On Friday, the southern Canadian shortwave is projected to dig towards the western Great Lakes and be followed by a more potent shortwave that is currently over northern Alberta. This should shunt the upper ridge axis back westward over the Northern Rockies for Friday as a broad surface ridge nudges into the region from the northwest. This should provide a quiet weather day and at least a little bit of relief from the heat. But it will still be quite warm across southern North Dakota with highs reaching the lower to mid 90s. Forecast highs elsewhere on Friday are in the 80s. On Saturday, the upper ridge is forecast to begin shifting back eastward. Some models bring a weak shortwave into western North Dakota Saturday morning, but higher chances for showers and thunderstorms enter the forecast Saturday evening through Sunday morning as shortwave energy over Canada drives a surface trough into the Northern Plains. The timing of the strongest forcing is not as favorable for severe convection, but it would be too soon to rule out that threat. The upper ridge begins to flatten in earnest on Sunday as another shortwave digs into the southern Canadian prairie provinces, but not in time to prevent yet another day of hot temperatures around 90 north to near 100 southwest. Supplemental heat risk forecasting tools are not quite as excited as they have been over the last week, likely owing to a couple of slightly cooler days that are forecast in between.

Ensembles remain confident in cooler but still near normal temperatures next week with highs mostly in the 80s as deep troughing emerges from Hudson Bay to the eastern Great Lakes, with the upper ridge reestablishing itself over the Rockies. The resulting northwest flow pattern over the Northern Plains could bring some low chances for showers and thunderstorms across the area from time-to-time next week, but predictability remains low.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1240 PM CDT Thu Jul 16 2026

VFR ceilings and visibility found at most terminals to begin the 18Z TAF period. MVFR ceilings are expected to linger at KXWA over the next few hours, but will improve to VFR heights by the mid afternoon. Late this afternoon into the this evening, isolated showers and thunderstorms may develop across portions of central North Dakota. Predictability in timing and location is low at the time of this update. Where thunderstorms do develop, expect gusty and erratic winds. Tonight into Friday morning, low MVFR to IFR ceilings are expected to develop across portions of the area, including the terminals of KMOT, KDIK, and KJMS. IFR to LIFR ceilings and patchy fog is possible at KXWA overnight through mid Friday morning. Low stratus and fog is expected to lift by the mid to late Friday morning, leaving VFR ceilings and visibility at all terminals through the end of the TAF period. Light winds at the start of the TAF period are expected to strengthen and organize out of the north to northwest as an inverted surface trough lifts across the forecast area, before again weakening and becoming variable this evening. Winds are then expected to reorganize out of the north and strengthen Friday morning and afternoon.

BIS WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 10 PM CDT /9 PM MDT/ this evening for NDZ017>020-022-023-025-031>033-035>037-040>044-046>048-050-051- 057>062.