522
FXUS63 KFGF 301924
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
224 PM CDT Sat Aug 30 2025

.KEY MESSAGES...

- Fog development is again expected tonight into Sunday morning.

&&

.DISCUSSION...
Issued at 224 PM CDT Sat Aug 30 2025

...Synopsis...

As has been the story now for several days, this FA remains in an
area of weak flow and forcing, resulting in mostly sunny skies, and
light winds. Outside of a few diurnally driven showers, dry weather
will continue today and Sunday.

An approaching wave on Monday will provide enough forcing late in
the day to spark off some showers and thunderstorms. There does look
to be at least some instability (up to 1000 J/Kg), but shear remains
weak ( < 25 knots) and moisture throughout model sounding profiles
leaves much to be desired. Therefore, while gusty winds, lightning
and brief heavy downpours look likely, severe weather is not
anticipated at this time.

A well advertised trough digs into the Northern Plains and Upper
Midwest midweek. In response, a strong cold front will push through
the region Tuesday. Behind the front, strong cold air advection will
drop temperatures drastically, resulting in widespread highs in the
50s on Wednesday. Even with questions regarding the high pressure`s
placement and any lingering cloud cover, Wednesday night into
Thursday morning is showing a strong signal for temperatures
dropping into the 30s across much of the FA. The NBM now shows
probabilities of dropping to or below 36 degrees Thursday morning
above 40% for most locations north of I-94. Parts of NW MN have
probabilities of dropping to 32 degrees or colder at 30%. However
you look at it, it is going to cool down dramatically by mid to late
portions of the week. A few showers will also linger behind the
front, which leaves some very low precipitation chances in the
forecast midweek.


...Fog Tonight...

Fog has been a problem several of the last nights. We remain in a
very similar pattern as previous nights: light winds, boundary
layer moisture from diurnal showers, and clear skies to promote
efficient radiational cooling. Sticking with a persistence forecast,
fog is expected develop tonight across much of the area. The
question is how widespread it becomes. If the past few nights are
any indication, dense fog will remain more patchy in nature, with
breaks in between the thickest spots. This will be something to
monitor as we go through the overnight hours.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1238 PM CDT Sat Aug 30 2025

VFR through the afternoon into the early overnight period. The
only exception to this would be if the afternoon cumulus deck
thickens enough to become BKN, but at this time kept TAFs free
of a ceiling. Overnight, fog is again expected to develop. The
question is not if, but where fog forms. This morning it
occurred at  4 out of 5 TAF sites. With a near identical
meteorological setup tonight, thinking we should again see fog
at a majority, if not all terminals. Therefore, put in an IFR
period from 9z to 14z at all TAF sites. There will likley be a
period of LIFR where the densest fog forms, but predictability
is too low at this time to discern where that will be. Fog will
burn off mid morning Sunday, returning ceilings and visibilities
to VFR.

&&

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

&&

$$

DISCUSSION...Rafferty
AVIATION...Rafferty