939
FXUS63 KFGF 291502
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1002 AM CDT Fri Aug 29 2025

.KEY MESSAGES...

- Showers and a few thunderstorms across mainly west central
  Minnesota could bring lightning and brief downpours this
  afternoon and evening.

&&

.UPDATE...
Issued at 1002 AM CDT Fri Aug 29 2025

Fog is eroding across the region, with the most persistent band
from Otter Tail county north to the Lake of the Woods region.
Even within this band, METARs show rapidly improving visibility,
therefore not expecting the remaining areas of fog to last for
much longer. Blended in the latest observations, otherwise the
forecast remains on track.

UPDATE
Issued at 718 AM CDT Fri Aug 29 2025

Stratus and fog has developed across portions of the Red River
Valley as well as MN lakes country. Some spots are down to 1/2
or even 1/4 mile, but coverage still looks pretty patchy on web
cams. Have SPS out for patchy dense fog. Adjusted POPs a bit for
showers down in west central MN. So far not much lightning
activity, but will monitor.

&&

.DISCUSSION...
Issued at 348 AM CDT Fri Aug 29 2025

...Synopsis...

Water vapor loop shows fairly weak upper flow across most of the
Plains and Rockies with several weak embedded shortwaves under
upper ridging. The most prominent of these is near the WY/SD
border but another weak ripple near the ND/SD border is
producing some cells just west of our CWA. Surface front stalled
near the Red River will also cause some showers and
thunderstorms to develop later this afternoon. The stronger
upper vort to our west looks at this point like it will wobble
down into SD and then Neb, but will keep an eye on it in case
some shift happens in our direction. Better chances for one of
the weak embedded shortwaves to come over our CWA will be on
Monday as ensembles are in decent agreement bringing one down
from Canada. Upper flow becomes stronger Tuesday and into mid-
week as a more robust trough digs down through southern Canada
and into the north central CONUS. Can`t completely rule out some
strong to severe storms developing as deep layer shear improves,
but instability will be in question depending on timing of the
cold front. ECMWF EFI doesn`t show any strong signals for CAPE,
and CIPS analogs are not really favorable, but some of the GEFS
machine learning has a 0.5 to 5 percent probability for severe in
our south for Tuesday. Not really enough to start messaging but
will keep an eye on how things develop. Northwesterly flow on
the backside of the upper low setting up over the Great Lakes
should bring fairly quiet and cooler weather for the end of next
work week.

...Thunderstorm chances today...

With weak upper flow the 0-6km bulk shear will remain around 20
to 25 kts this afternoon, even as there is a 70 percent
probability of 1000 J/kg of CAPE by this afternoon south of the
I-94 corridor. Joint probability of at least 500 J/kg of CAPE
and shear getting up to 30 kts is around 10 to 20 percent in
portions of west central MN this afternoon. Not enough for
organized severe, but think some stronger storms could pulse up
at times this afternoon and evening. A few blotches of decent
updraft helicity pop up in the HREF and some of the CAMs are
showing some decent cells. Chances for severe are low but will
have to watch for lightning at outdoor events to start the Labor
Day weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 718 AM CDT Fri Aug 29 2025

Fog has brought several locations down to very LIFR, with vis
down to 1/2 or even 1/4 mile at the MN airports and KGFK.
Expect some mild improvement to IFR in the next hour or two,
and then fog should be burned off by 15Z or so. Conditions
should be VFR for the rest of the day. Winds that are light and
variable will become more consistently out of the southeast by
the end of the period.

&&

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

&&

$$

UPDATE...Rafferty/JR
DISCUSSION...JR
AVIATION...JR