textproduct: Grand Forks

KEY MESSAGES

- Rain ends from west to east during the day. Localized flooding impacts may be found this morning in a zone from Thief River Falls to just south of Grand Forks to north of Valley City.

UPDATE

Issued at 449 AM CDT Tue Sep 29 2026

Flood watch for parts of southeast ND including Fargo-Moorhead will expire on schedule. The heaviest rainfall overnight fell more north of the watch area, with the exception of Barnes county. Overnight the heaviest rainfall with amounts of 1.50 to 2.50 inches 06z-09z fell from near Valley City northeast to just south of Grand Forks to near Thief River Falls. Since 08z the rates of rainfall have diminished greatly with 1 hour rainfall rates from radar showing 0.10 to 0.20 inch. Will continue current areal flood warning and flood advisory for parts of the Sheyenne River basin where total rainfall of 4-6 inches has fallen in the last 24 hours. Rainfall will end from west to east gradually today...taking the longest to exit Bemidji-Fergus Falls which wont be til later afternoon. But also this area has received much lighter amounts of rainfall so far.

..Potential flooding impacts this afternoon & tonight

There remains potential for an additional 3 to 6 inches of rainfall this afternoon through tonight in portions of southeast ND, central/southern Red River Valley, into northwest MN. The majority of CAMs continue to paint this scenario somewhere within the aforementioned areas, but each with their own variety of exactly where this will occur. Locations that experience these amounts are liable to see flooding impacts.

Confidence is relatively high in this output based on the presence of a stationary boundary extending southwest to northeast generally from the southern James River Valley in southeast ND into the central Red River Valley into northwest MN. This sets the stage for additional upper forcing to act upon, which is well advertised to resurge tonight in the form of a shortwave trough propagating out of the High Plains of WY/SD, through the Dakotas, and into northwestern ON by Tuesday morning. This will help reinvigorate the low level jet within the "warm sector" of the aforementioned stationary front - suggested to generally remain in this orientation/position through the event, with some eventual movement eastward Tuesday morning.

Abnormally high moisture content (~1.5 inches of PWATs) coupled with weak but sufficient instability (MUCAPE ~800 J/kg), and storm motion generally parallel to frontal orientation will drive high rain rates. Rain rates like 0.5-1" per hour and/or 2-4" per 6 hours will result in areas that see repeated thunderstorms move over any particular location for at least 2 hours.

Pre-conditioned areas that have recently experienced soaking rainfall is also important to consider when identifying potential areas for subsequent flooding impacts. While these advertised highest rain rates may occur in northwest MN, higher rain amounts from this morning have generally missed this area. Conversely within southeast ND, rainfall from this morning in the 1-2 inch range have already occurred, with continued convective rates from thunderstorms still ongoing in southeast ND at the time of this Forecast Discussion issuance. Despite this area in drought, higher rain rates coupled with previously/currently received rainfall still allow for excessive runoff.

Of course, urban areas are relatively more susceptible to these higher rain rates; this includes cities like Fargo-Moorhead and/or Valley City.

While the overall area of concern holds generally medium to high confidence, more precise location of highest rainfall amounts remain in question. Because of this, have opted to not issue a Flood Watch; however, a Flood Watch may be issued should confidence increase in more precise location of potential area of concern later this afternoon/early evening.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1153 PM CDT Mon Sep 28 2026

Highly variable flight conditions as a frontal zone lingers over the region and clusters of showers and embedded thunderstorms track southwest to northeast. Many locations are reporting MVFR and IFR conditions. Stratus should fill in through the overnight hours and IFR ceilings will become predominant with the potential for LIFR (mainly KDVL). Fog may also develop in areas outside of showers tonight/Tuesday morning. Drier air does eventually arrives Tuesday and VFR should return to ND by early afternoon, with a slower west to east period of improvement in the afternoon/evening across northwest MN. MVFR ceilings may linger over north central MN including KBJI through Tuesday evening.

FGF WATCHES/WARNINGS/ADVISORIES

ND...None. MN...None.