455
FXUS63 KFGF 172350
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
650 PM CDT Tue Jun 17 2025

.KEY MESSAGES...

- Active weather will continue through Sunday. Strong to severe
  storms are possible, particularly late week into the weekend.

- Heat will develop this weekend, bringing potential heat
  related impacts to outdoor events.

&&

.UPDATE...
Issued at 650 PM CDT Tue Jun 17 2025

Benign conditions across the FA this evening. A field of cumulus
developed this afternoon, slowly waning with the loss of diurnal
heating. The handful of thunderstorms that popped up have
dissipated or progressed out of the FA.

&&

.DISCUSSION...
Issued at 130 PM CDT Tue Jun 17 2025

...Synopsis...

Surface analysis this afternoon indicates a very diffuse weather
pattern across the Northern Plains this afternoon. Northwesterly
flow aloft is settling in as a weak trough axis is working
eastward over the Minnesota/Dakota state lines. With the
lingering instability this afternoon, isolated showers have
developed despite very limited forcing. Gusty winds and small
hail may accompany some of these showers if they can become
sustained thunderstorms, however that appears very unlikely at
this time. With the sparseness of the showers today, don`t
expect rainfall specifically at your location.

Tonight will keep light winds over the area with the potential
for additional fog to develop overnight into the morning.
Dewpoints this afternoon are dropping with time due to weak dry
air advection, so the greatest chances for this will be where
the upper 50s dewpoints should remain, which is in west-central
Minnesota.

Looking ahead to Wednesday, a front will sweep down tomorrow
afternoon, bringing the chance for more organized convection.
Conditions should warrant the development of at least strong
storms with a marginal risk for severe thunderstorms. Once that
weak front pushes through, we will very quickly heat up once
more Thursday as upper ridging will begin to push away from the
Intermountain West. Flow will also amplify over the top of the
ridge axis, which sadly will be right on top of us. For this
reason, we will have a combination of instability, shear, and
moisture, although much less certain is forcing itself being
enough. Regardless, expect at least daily chances for strong to
severe thunderstorms in the afternoon with the potential for
additional strong to severe storms in some overnight periods.
Large scale ridging will be replaced by southwest flow aloft by
this weekend, bring a much stronger chance for more organized
severe convection and increases in moisture content should
facilitate strong instability across the Northern Plains. Once
this trough ejects by Sunday, we will see much cooler
temperatures and the severe risk should start to go down once
again, as reflected in CSU Machine Learning Probabilities.

...SEVERE CHANCES THROUGH THE WEEKEND...

For tomorrow: A cold front will push through the area tomorrow
afternoon. Forecast dewpoints generally range in the low to mid
50s by mid to late afternoon with a very dry, well mixed
profile. With the decent forcing along the cold front, the
expectation is for scattered showers and thunderstorms to form
along this front. As stated above, well mixed profiles should
allow for damaging wind gusts to arise in some downbursts,
although the likelihood of this being widespread along the line
is low. A hail risk may develop with any convection if better
saturation arises but as of now the wind risk will be the main
issue. Moisture content being as low as it is will prevent a
supercellular tornado risk tomorrow afternoon.

After Wednesday: Southwesterly flow will advect in Pacific
Moisture into our area with lower level southerly flow allowing
for gulf to monsoonal moisture to push into our area. This will
allow for very strong instability to develop across the area and
linger through Sunday. Upper forcing looks to be fairly weak
Thursday, however a strong low level jet looks to develop
Thursday night into Friday morning. Confidence in scope of
convection tied to this is low, but it does appear like heavy
rainfall will be possible should this LLJ arise and the nose of
it pushes into our area.

Friday currently has the strongest signal for organized severe
convection, although the question of what hazards arise will
depend on storm mode and mesoscale features. The synoptic
pattern does support frequent afternoon severe convection,
particularly Friday into Saturday. As the trough begins to
propagate eastward, there is a high likelihood that additional
showers and thunderstorms will accompany a cold front, although
confidence in timing diminishes the predictability in details.

The basic summary is this: we are heading into an active pattern
of severe thunderstorms, particularly ones with higher impacts.
Be prepared if you are heading out camping this weekend or
headed to a lake and have multiple ways to receive warnings
should severe convection arise.

...HEAT THIS WEEKEND...

Moisture return and increasing temperatures will allow for
hazardous heat conditions to develop. While heat index values
are currently forecasted to be below Heat Advisory criteria, Wet
Bulb Globe Temperature and HeatRisk forecasts do paint higher
tiers of impacts stretching from southeast North Dakota into
northwest Minnesota where dewpoints should exceed 70 in some
locations. For this reason, it is worth mentioning to at least
expect some impacts to outdoor activities from heat. Make sure
to remain hydrated and take frequent breaks if going outdoors
this weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 650 PM CDT Tue Jun 17 2025

TAFs are VFR throughout the period, but several challenges exist
that may bring impacts to terminals Wednesday. First is the
potential for fog Wednesday morning. Radiational cooling should
allow for at least patchy fog to develop. Will this fog be
widespread enough or happen to set up over any one TAF site to
is too early to say. After that, attention turns to Wednesday
afternoon and evening. Thunderstorms are expected to develop
along a front, bringing with them the potential for heavy rain,
lightning and strong winds. The northern TAF sites of KDVL, KGFK
and KTVF have the best chance of seeing a storm. However, due
to storms developing near the end of the TAF period, and the
uncertainties associated with if they will prevail at any one
site or remain in the terminal`s vicinity. Storm
coverage/location will be refined in the next several sets of
TAFs as we approach the event.

&&

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

&&

$$

UPDATE...Rafferty
DISCUSSION...Perroux
AVIATION...Rafferty