textproduct: Bismarck

KEY MESSAGES

- Isolated thunderstorms continue to dissipate this evening as they drop south through central and eastern North Dakota.

- Cooler on Tuesday, then a warming trend commences with very hot conditions returning this weekend with high temperatures and heat index values potentially above 100 degrees.

UPDATE

Issued at 850 PM CDT Mon Jul 20 2026

One small area of thunder dropping south through Stutsman County attim. Otherwise convection has ended over western and central ND. The Red Flag Warning has also been allowed to expire. Made a few tweaks to pops based on latest radar, otherwise no changes to the going forecast.

UPDATE Issued at 558 PM CDT Mon Jul 20 2026

Isolated thunderstorms continue to drop southeast from Canada into the northwest and north central portion of the state. Around 700-900 J/KG of Cape available and moving into some better bulk shear as cells move south. Could be a stronger cell with small hail and locally gust winds. Will continue to monitor. Winds will diminish this evening, with another night of comfortable temperatures, mainly in the 50s to lower 60s.

DISCUSSION

Issued at 200 PM CDT Mon Jul 20 2026

Currently a large upper level high is in the Central Plains with a ridge building in the Pacific Northwest. In the Northern Plains quasi-zonal flow with a slight northwest tilt is present. A small upper level low is about to dig through the Lake Superior region, with a trailing cold front in southern Canada to its west. At the surface this cold is present too, currently nearing the North Dakota border. Ahead of the front is low cumulus clouds in northern North Dakota, and breezy northwest winds across the state from the cold front last night. This evening that cold front might kick off scattered showers and maybe a thunderstorm in the north and central. With almost no CAPE but 40kts of shear, a brief strong storm is possible with small hail.

Tuesday will be the coolest day of the forecast period with highs slightly below normal in the 70s and 80s as the flow turns more northwest before the incoming ridge. The rest of this week however the strong warming trend will start once again. The current ridge in the Pacific Northwest will slide east to the Northern Plains with the ridge axis ending up over the western part of the state on Saturday. A strong thermal ridge will follow with temperatures at 850mb nearing 100 degrees over the state on Saturday, with the compressional heating of that air mixing down, the current NBM highs this upcoming weekend around 105 in the southwest and south central. Looking at the NBM percentiles, these deterministic values are actually only the 50th percentile. The 90th temperatures are close to 110 in the south. It is very possible that the NBM currently has a warm bias because we have been so far above normal in the last few weeks, and this incoming ridge actually looks a little weaker and less humid than the last one. Only time will tell on what high temperatures actually happen. Saturday the ridge breaks down back to near zonal flow, leading to slight chances for showers and thunderstorms Saturday with the flow off the mountains. The rest of the weekend will continue to be very warm. Heat products will likely be needed again.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 558 PM CDT Mon Jul 20 2026

High pressure will build over the forecast area through the 00Z TAF period. Mostly VFR conditions are expected but there will be scattered low VFR to possibly MVFR clouds around tonight into Tuesday morning, with a local MVFR ceiling not out of the question, but uncertainty is too high attim to include in any TAF site. Strong northwest winds early this evening will diminish by mid evening, then generally a light northerly flow through the remainder of the TAF period.

BIS WATCHES/WARNINGS/ADVISORIES

None.