926
FXUS63 KFGF 050458
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1158 PM CDT Fri Sep 4 2026

.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.

&&

.DISCUSSION...
Issued at 241 PM CDT Fri Sep 4 2026

...Synopsis...

Upper ridging will continue to amplify over the Plains tonight
and into the weekend. Several weak shortwaves riding through the
upper ridge will bring on and off shower and thunderstorm
chances through the next few days. There is some probability of
fog redeveloping in our far eastern counties as well as running
up into the higher terrain on the edge of the northern Red
River Valley. On the other hand, there will be some mid level
clouds coming in tonight with one of the embedded shortwaves,
which may inhibit fog formation. Not much change in the pattern
Saturday and Sunday with additional weak embedded shortwaves and
southeasterly surface winds ahead of the surface trough. Flow
become more southwesterly on Monday as the ridge axis shifts
east, with another shortwave coming through. Upper troughing
begins to move into south central Canada on Tuesday and then off
to the east after, leaving the area in near zonal to slightly
northwesterly flow. A few weak embedded shortwaves could bring
some precipitation chances and above average temperatures
continue.

...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 /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1152 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, as well as a medium
chance for storms.

Regarding the medium chance for thunderstorms to impact sites
like KDVL, KFAR, and KGFK, confidence has increased some in
this potential impact to these sites from storms. There is
currently showers and storms in south-central into southeast ND,
migrating toward the east and northeast. Storms may weaken as
they move, however, expectation is for additional storms to
develop in their wake. This generative area of storms is
forecast to move toward eastern ND by 09Z. There is still not
high confidence in any particular storm to impact the site,
however, confidence is high in the potential now.

Regarding lowered ceilings and potential fog, the area of
MVFR to IFR ceilings within central MN continues to migrate
westward into northeast and west-central MN. This will impact
KBJI through at least 15Z, and potentially extend as far as KTVF
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 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.

&&

$$

UPDATE...CJ
DISCUSSION...JR
AVIATION...CJ