509
FXUS63 KMPX 070819
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
319 AM CDT Mon Jul 7 2025

.KEY MESSAGES...

- Shower & thunderstorm chances return this afternoon and evening.
  Slight Risk (Level 2/5) of severe weather across western MN.

- Next best chance for more widespread showers and storms
  arrives Friday.

&&

.DISCUSSION...
Issued at 315 AM CDT Mon Jul 7 2025

PATCHY FOG POSSIBLE THIS MORNING...It`s a quiet start to the
day across the Upper Midwest, with mostly clear skies and 3 AM
temperatures in the low to mid 60s. Winds are light, which will
promote the potential for ground fog to develop as temperatures
cool towards the dew point over the next few hours. We`ve seen
this idea come to fruition at Benson, where recent obs indicate
that visibility has dipped to a mile and a half. While pockets
of fog are possible across far western/central MN (like the
Benson case), the main area to watch for fog development will be
across southern MN/western WI where a pool of 62-65 degree dew
points exists. Fog should erode fairly quickly this morning as
mixing begins shortly after daybreak.

STORM CHANCES LATER TODAY...GOES water-vapor imagery captures a
shallow shortwave trough over the International Border between
Montana and Saskatchewan. The eastward movement of this feature
will push a frontal boundary across the Dakotas today, serving
as the forcing mechanism for thunderstorms. While variations
exist across the CAM suite, the consensus is that one, or
possibly multiple clusters of storms will develop across the
Dakotas and move east into western Minnesota this afternoon.
Damaging wind gusts will be the primary threat as storms cross
the state border. Should storms remain in multi-cell clusters,
large hail would also be possible. On the other hand, upscale
growth into a bowing segment would likely limit the hail threat
but could enhance the damaging wind threat. Regardless of how
the convective scenario unfolds, locations across western MN are
under the highest threat for severe storms given ~2000+ J/kg of
MUCAPE and 30-40kts of effective shear. SPC has introduced a
Day 1 Slight Risk (2/5) for aforementioned threats along and
west of a line from Granite Falls-Willmar-Alexandria. A Marginal
Risk (1/5) extends east of this area to a line from Waseca to
New Richmond (this includes the Twin Cities Metro). Weaker
instability and shear, as well as stable lapse rates and the
loss of daytime heating should promote weakening of any convective
complex/clusters as they move east across MN/WI this evening.
Still, an isolated damaging wind gust will remain possible. We
have lowered PoPs to "Chance ~30-40 percent" across eastern
MN/western WI, given the expectation that storms will be decaying
with eastward movement tonight, which will result in a lower
precipitation footprint. One other item to mention, should a
more substantial bowing MCS take shape across SD, our current
thinking is that is would track southeast along the instability
gradient which supports the greater coverage of the Slight Risk
to the southwest across WFO Sioux Falls forecast area.

REST OF THE WEEK...Relatively quiet weather returns following
today/tonight`s thunderstorm chances. It looks like we may be
contending with another round of ground fog tomorrow morning due
to clearing skies and light winds, along with the moisture from
the rain chances. Airmass showers/isolated t-storm will be
possible Tuesday across SE MN/W WI, though the severe weather
threat is low. Afternoon highs warm into the lower 80s both
Tuesday and Wednesday. By Thursday, an upper-level ridge axis is
forecast to be positioned over the Great Lakes, with troughing
beginning to dig into the Pacific Northwest. Southwesterly
flow/warm advection will begin to increase in response the
troughing, which will push temperatures into the mid 80s (upper
80s across western MN)for Thursday`s highs. A vort max at the
base of the trough is progged to slide across northern CONUS
heading into Friday and serve as the focus for widespread rain
and thunderstorms to end the work week. As you may imagine,
there is some spread in guidance with respect to timing and
coverage of precipitation, however feel that the latest PoPs
from the NBM are reasonable: Chance PoPs beginning later
Thursday evening and increasing to likely PoPs through Friday
morning/midday. Cooler temperatures will follow the rain chances
for the upcoming weekend, which is reflected in the NBM with
highs in the 70s. Medium to long range ensemble guidance shows
height rises early next week which would bring back Summer
warmth and storm chances heading into the middle of the month.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1219 AM CDT Mon Jul 7 2025

Light winds and a pool of moisture across southern MN/western WI
will be the focus for ground fog after 9z at MKT, EAU, & RNH.
Maintained the going TEMPO groups for a period of visibility
reductions at each of these terminals. Focus then shifts to
thunderstorm chances starting later in the afternoon. Following
the latest hi-res trends, kept the TEMPOs for -TSRA at RWF &
AXN, and added a PROB30 at STC. Storms are forecast to weaken
with eastward movement heading into this evening, so did not
have confidence to include thunder at MKT/MSP/RNH.

KMSP...No major changes to the 6z TAF, as confidence remains too
low to include thunder after 00z. Will likely be contending
with showers as decaying thunderstorms move east across the
area.

/OUTLOOK FOR KMSP/
TUE...VFR. Chc IFR cig/vis in mrng. Wind WNW 5-10 kts.
WED...VFR. Wind light/variable.
THU...VFR. Chc TSRA overnight. Wind SSE 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.

&&

$$

DISCUSSION...Strus
AVIATION...Strus