textproduct: Grand Forks

KEY MESSAGES

- Additional chances for strong to severe thunderstorms exist over the holiday weekend.

UPDATE

Issued at 935 PM CDT Fri Sep 4 2026

Latest 00Z guidance generally agrees in scattered showers and thunderstorms in eastern ND overnight tonight into Saturday morning. This is driven by developing low level jet helping advect and lift higher moisture out of SD into ND.

While majority of guidance depicts convection, there are noteworthy differences in strength of storms within guidance. A cluster of guidance depicts robust thunderstorms, with the other cluster keeping storms weak. This could be attributed to uncertainties in degree of forcing within the zone of lift on the periphery of the low level jet, as well as the low level jet not being particularly strong. Should storms become robust, there is the possibility of hail given sufficient shear and instability, favorable shear orientation, as well as the elevated nature of storms.

Further expanding uncertainty is how large hail may get should hail production occur. Soundings in the forecast near storm environment have concerningly numerous analogs with very large hail at least 2 inches. While this is not the favored scenario (mainly due to expectation of forcing to sustain robust thunderstorms to be on the weaker side), it is something to be mindful of.

..Severe chances over Labor Day weekend

First of several shortwaves under the upper ridge comes in tonight, and with warm air advection, some showers and thunderstorms are possible. Main activity will be in our far western counties, although it is uncertain how far east the decent elevated instability will move. Some of the CAMs have some fairly healthy thunderstorms developing over southeastern ND after 10Z tonight, while other runs have showers or nothing at all. The HREF has some low probabilities (10 percent) of strong updraft helicity tracks early tomorrow morning, so can't completely rule out some elevated hailers but not super widespread. Another shortwave coming through Saturday afternoon or night could bring additional convective activity, but the deep layer shear is pretty unimpressive at around 25 kts. Slightly better shear and instability on Sunday over eastern ND, although much will depend on how previous convection plays out and exact timing of the embedded waves. Best shear will be Monday afternoon, although CAPE values are all over the place. In short, there will be several chances for a few isolated severe cells to develop Saturday through Monday, but exactly where and when are uncertain.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 935 PM CDT Fri Sep 4 2026

Forecast impacts to TAF sites main stem from lowered ceilings and chance for fog, of which may be dense. There is also a low chance for thunderstorms to impact sites like KDVL, KFAR, and KGFK, although confidence in this occurring is low. Did not include any mention of -TSRA/CB because confidence is so low.

Area of lowered ceilings in the MVFR to IFR category within central MN is working its way westward. This will impact KBJI through at least 15Z, and potentially extend as far as KTVF and/or KGFK between 09Z-15Z. This also includes a medium chance for fog at KBJI, of which may be dense. Opted to include a TEMPO group at KBJI to note most likely timeframe for this to occur. Also, included 4SM BR at KTVF and KGFK between 11Z-15Z as there is a low chance for fog to impact these sites, potentially as early as 09Z. Confidence is not as high in this occurrence compared to KBJI.

After 15Z, low clouds will tend to lift and gradually diminish, with the exception of KBJI where low ceilings may linger. Otherwise, generally east to southeast winds 10-20kt are forecast through the afternoon.

FGF WATCHES/WARNINGS/ADVISORIES

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