textproduct: Bismarck

KEY MESSAGES

- Excessive rainfall could cause localized flooding from south central North Dakota to the James River Valley through tonight.

- Mostly dry with near normal temperatures from Tuesday into the weekend.

UPDATE

Issued at 638 PM CDT Mon Sep 28 2026

The main forecast update was to clean up pops this evening. Thunderstorms are currently exiting the far southeast Stutsman county. A few thunderstorms were also pushing into the far south central, from north central SD. A couple storms were also firing over western ND where we had some daytime sunshine. Don't think these will last too long. The main area of concern is the far south central into the JRV, where we issued the Flood Watch. However, we are in a bit of a lull before the next wave provides the forcing for additional showers and thunderstorms over south central ND. The main limiting factor is the convective potential. Most of the instability is in the southwest and with the loss of heating, expect CIN to be on the increase. If we get more stratiform rain with embedded some embedded thunder, the potential for excessive rain will be less. We we can get the forcing to get another round of thunderstorms in this same general area, the potential for excessive rain increases, especially for those areas that had a round of rain this afternoon. Guidance suggest rain/thunderstorms will be on the increase over south central ND this evening. Will continue to monitor.

UPDATE Issued at 544 PM CDT Mon Sep 28 2026

We have issued a Flood Watch for a portion of south central ND, including the James River Valley. This narrow area received anywhere for 1-3 inches of rain this afternoon. A warm front remains situated over the area, and another round of thunderstorms, some with very heavy rain, is possible again this evening into early Tuesday morning. Flooding of urban and low lying areas will be possible tonight, especially for those that received an earlier round of heavy rain this afternoon. The Flood Watch does include Stutsman county, but far southern Stutsman is the area that received the heavy rain, in fact it's still raining in far southeast Stutsman attim, so the far southern portion of the county is our main concern.

DISCUSSION

Issued at 150 PM CDT Mon Sep 28 2026

Currently a very deep trough in Nevada is causing southwest flow over the Northern Plains. East of the Mississippi River is a ridge pattern. At the surface a low pressure system is working into the western Dakotas, with widespread rain to its east along a stationary front. This front is located just south of Interstate 94 from west to east. Along the frontal zone, several inches of rain has fallen between the Missouri River and Ashley, ND. For this reason a Flood Advisory has been issued until 3pm. Western North Dakota is now in the dry slot of the low.

This evening model guidance suggests a redevelopment of showers and maybe a thunderstorm in the south central and east. Models have very little MUCAPE, less than 400 J/kg, this evening and overnight. The rain shower development will likely be along that stationary front as it slowly slides north in the surface cyclonic flow. On the backside of the low, fog may be possible across the forecast area until the late morning.

The rest of this week the pattern will change to zonal flow over the Northern Plains, allowing all this rain that just fell to dry out. No rain is then in the forecast until this weekend when an Alberta Clipper slides into the state Friday night. Temperatures through the week will stay near normal in the 60s to lower 70s as the zonal flow keeps things steady.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 638 PM CDT Mon Sep 28 2026

Isolated thunderstorms are possible this evening in western ND. Showers and thunderstorms, some with very heavy rain, area expected to move across far south central ND and into the James River Valley. In this area, expected MVFR-IFR ceilings and visibilities in thunderstorms with heavy rain this evening into the early overnight hours. Elsewhere areas of fog are possible across all of western and central ND tonight into Tuesday morning. A cold front will move west to east through the state Tuesday, turning winds west to northwest, ending any precipitation and clearing skies.

BIS WATCHES/WARNINGS/ADVISORIES

Flood Watch through Tuesday morning for NDZ037-046>048-050-062.