textproduct: Grand Forks

KEY MESSAGES

- There is increasing confidence in the potential for large to very large hail across southeast North Dakota tonight.

- There is low confidence in nebulous chances for strong to severe storms through Tuesday night.

..Synopsis

A primarily zonal jet stream remains fixed across the northern CONUS this weekend into early next week with low amplitude shortwaves riding across the top of a flattened ridge centered across the four corners and extending east into the ArkLaTex. Through the week ridging becomes more pronounced as it shifts east across the southern plains with the jet becoming more anti- cyclonically curved and steering shortwaves more to our north in southern Saskatchewan and Manitoba decreasing chances for rain after Tuesday. Notably we do not look to warm up with this round of ridging so temps will remain in the 70s and low 80s through the next several days for highs.

- Severe risk tonight

Given the increasing density of CAMS and machine learning all highlighting south central and southeast North Dakota this evening there has been a 5% CIG1 introduced for large hail this afternoon. Confidence in coverage still precludes any categorical upgrades however. With most models now honing in on somewhere around 2000 MUCAPE this evening and shear in the neighborhood of 40-50kts, robust rotating elevated supercells seem to be the preferred storm mode if storms form. Weak forcing comes in the form of theta-e advection along a 925-850mb front that will slowly sag south through the night. Sounding analogs support this conceptual model with multiple events of 2.5-3" hail coming up in the SARS system. Even on a low end the expectation tonight (if storms form) would likely be 1.5-2" hail. Given the expected elevated nature of storms the tornado threat looks to be near zero with wind an some uncertainty but perhaps a risk for 60-70mph if a cold pool can establish itself amid the 900-1200 DCAPE. The main threat overall looks to be the hail though from 8pm to as late as 5am with multiple rounds of storms possible.

- Sunday and beyond

With the active zonal jet numerous shortwaves are likely to rotate into the northern plains with machine learning fixating more on the MT/WY/western Dakotas corridor for typical late summer high plains action. However, an at least buoyant airmass comprised of daily SBCAPE values of 500-1000 j/kg and enough shear for some degree of storm organization, and a conditional hail and wind threat is likely to persist each day through Tuesday across the western and southern portions of the forecast area.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 627 PM CDT Sat Aug 8 2026

VFR conditions all all TAF sites as even with a frontal boundary draped across the area, only some cumulus near the international and South Dakota borders. Should see clouds increasing a bit later tonight, but think that any ceilings will remain VFR. Convective chances are all over the place, so will keep prob30 groups going with just some adjustments for what looks to be later initiation. Best chances for convection will be after 04Z, and some spot many not see anything until a few hours after that. Winds that are currently south at KFAR and KBJI and from a more northerly direction at the northern TAF sites will become all north to northeasterly as the cool front pushes down later tonight and into tomorrow. Speeds should remain below 12 kts.

FGF WATCHES/WARNINGS/ADVISORIES

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