460
FXUS63 KFGF 312054
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
354 PM CDT Sun Aug 31 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms are forecast late Monday
  through Tuesday.

- A seasonably strong cold front moves through Tuesday, bringing
  with it below average temperatures mid to late week.

&&

.DISCUSSION...
Issued at 258 PM CDT Sun Aug 31 2025

...Synopsis...

Weak flow regime over the majority of the northern CONUS is
discernible via water vapor imagery and upper air analysis.
Synoptic features of interest include upper ridging over western
ON, very weak upper troughing from western Dakotas into South
Dakota, and upper ridging extending out of the south-central
CONUS into the Interior Mountain West. Just on the northern limb
of GOES imagery, another important synoptic feature is starting
to become viewable: a relatively strong shortwave trough over
the Arctic.

The two aforementioned synoptic features will slide eastward
tomorrow, with upper ridging over the West helping slide the
Arctic shortwave trough southward through Canada into the
Northern Plains and Upper Midwest by Wednesday. With the arctic
shortwave trough comes seasonably cold air mass intruding upon
the north-central CONUS, with a strong cold front on the leading
edge of this air mass progged to pass through Tuesday. This
will drive below average temperatures next week into our area,
including the potential for frost/freeze in our area (more on
this below).

But first, sufficient instability and moisture will collect
ahead of the amplifying shortwave trough, bringing with it
scattered showers and thunderstorms late Monday and Tuesday.
Some of these storms may be strong (more on this below).

Behind Tuesday`s cold front, persistently gusty winds will
accompany cooling temperatures, likely lasting for several days.
This will be a marked change from recent, summer-like
conditions. Ensemble guidance strongly agrees the amplifying
shortwave trough to stall and deepen near the Upper Midwest and
Great Lakes regions mid to late week. This is supported by
reinforcing shortwave and additional feed of seasonably cold
continental air masses sliding out of northern interior Canada.
This should continue to support colder than average temperatures
into late week, particularly for Minnesota locations closer to
the now stalled and well developed upper low.

Cooling temperatures aloft and additional shortwave
impulses moving through northwest flow aloft will also aid in
supporting scattered shower activity into Wednesday and perhaps
Thursday. Cooling temperatures aloft may even support lake
effect processes supporting persistent, localized scattered
light shower activity. At this time, there is very little
support offered by guidance pointing toward potential light snow
in our area as temperatures are forecast to be just warm enough.
However, there is a small subset of guidance that allows brief
period of light, non accumulating snow within northwest
Minnesota early Wednesday morning and/or Thursday night/Friday
morning. Chance of this to occur is too low to include in the
forecast, however (around 10%).

...Thunderstorm chances late Monday and Tuesday...

High resolution guidance continues to support shower and
thunderstorm development starting late Monday near the SK/MB/ND
region, moving east and southeast with the impending cold
front/shortwave trough. Currently favored timing of the front
brings it through our area Monday night and Tuesday morning.
This is not favorable timing for more robust thunderstorm
chances as the cold front is forecast to move through the area
before peak heating. This still doesn`t mean strong storms will
not occur, but rather favoring more elevated, non-surface based
storms.

Weak instability is forecast to accompany the cold front. This
along with modestly increasing shear may allow for some strong
storms capable of producing small hail and gusty winds. Other
hazards such as tornadoes and flooding are not anticipated given
fast storm motion, limited moisture and instability, as well as
unfavorable wind shear orientation to the cold frontal boundary.

...Below average temperatures mid to late next week...

With temperatures of this degree moving into the region, it is
reasonable to expect some potential for frost/freeze in our
area, particularly the typical cold spots of northwest and
west-central Minnesota. As of now, there is a 30% chance
temperatures 35F or colder Wednesday night/Thursday morning within
these particular areas, and more like 10% elsewhere. This would
be seasonably early frost/freeze if it occurs, and potentially
impactful given the growing season still underway (albeit on the
tail end) and harvest just starting.

Factors that lower confidence include influence of potential
clouds (perhaps lake effect driven) as well as wind to mitigate
radiational cooling.

An additional shot of cold air may introduce an additional
chance to see frost/freeze in our area behind reinforcing cold
air mass intrusion Friday/Saturday.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 104 PM CDT Sun Aug 31 2025

VFR conditions will prevail through at least 09Z, with a low
chance for fog between 09Z-14Z.

Mostly clear skies are forecast today with the exception of
some daytime fair weather cumulus through 00Z. Winds will be
generally out of the south between 5-12kt until around 00Z when
winds lessen and become variable.

While fog is not likely tonight, there is a 20% chance for it to
form within portions of the Red River Valley into Minnesota,
including sites like KGFK, KFAR, KTVF, and KBJI. This fog could
be dense. Fog will start to form around 09Z and diminish by 14Z
if it does form.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.

&&

$$

DISCUSSION...CJ
AVIATION...CJ