513
FXUS63 KMPX 011709
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1209 PM CDT Tue Jul 1 2025

.KEY MESSAGES...

- Mostly quiet weather today, with light winds and sunny skies.

- Airmass storms possible again on Wednesday, better chance for
  showers/storms arrives Friday into Saturday along a frontal
  passage.

&&

.DISCUSSION...
Issued at 240 AM CDT Tue Jul 1 2025

Good Tuesday morning! Big picture-wise, we have an exiting upper
level trough and cold front along the East Coast this morning,
allowing a surface high to sprawl eastward over much of the
Mississippi Valley today. That means we can expect mostly sunny
skies and relatively light winds. Only thing to note is that
we`ll likely see some diurnally driven cu form during the
afternoon. Some of the CAMs hint at spotty showers (or virga
based on a somewhat dry boundary layer noted in forecast
soundings), primarily north of I-94 in western Wisco. Nothing to
change plans over.

On Wednesday, an upper low will slide east through southern
Canada. The attendant surface front should push south across
the Upper Midwest, providing a source of lift for isolated to
scattered storms to develop. The highest chances will be tied
closer to the Canadian low, across northern MN and northwest WI.
At the same time, a cluster of showers and storms could also be
sliding southeast across SD and SW MN under the nose of the LLJ
early Wed morning. The SPC did introduce a broad Marginal Risk
to cover these two areas of elevated convection given the 30 to
40 kts of 0-6km wind shear, and 1000 to 2000 J/kg MUCAPE that
develops during the afternoon. Much of central MN may be a dry
space between these two clusters of storms, similar to what the
06z HRRR suggests. Should storms develop though, the
environment could be conducive to marginally severe hail and
winds.

By Thursday, a building ridge to the west will begin to shift
its axis over the Northern Plains. We should see dewpoints and
temperatures start to rise a bit, especially across SW and
west-central MN where heat indices could climb into the low to
mid 90s. Some showers and storms look possible associated with
the northward tracking warm front, especially later in the day
as the LLJ increases and shifts east.

A lot of recent talk has been about Friday, and for good reason
given we could see a period of a couple different weather
impacts for a rather busy outdoor activity day. The ridge axis
will continue to shift east, leading to another, likely more
widespread, day of hot and humid weather. Expect heat indices to
approach or surpass 90F area-wide. There`s also been a
consistent signal for some type of broad troughing over the
Rockies, with a few embedded shortwaves ejecting northeast
across the Upper Midwest. This synoptic forcing combined with
the deep moisture transport of 2"+ PWATs means there could be an
elevated threat for heavy rain, as highlighted by WPC`s
marginal risk for excessive rainfall. That said, Independence
Day does not look like a washout by any means... rather when
storms form along and/or ahead of the frontal passage, they
could be pretty efficient rainmakers. Timing-wise, folks may get
lucky in eastern MN and western WI as the front (and therefore
best forcing for a line of storms) may not pass through until
late in the day Friday. Both the 18z deterministic runs of the
GFS and ECMWF for instance, have a line of storms develop and
move into parts of northern and western MN around 7-10pm. The
severe threat does not appear to be as impressive, with weak to
moderate lapse rates and wind shear. There is still time for
exact details to fluctuate.

Depending on the progression of that broad trough and surface
front, some showers and storms may linger into Saturday. As
winds shift out of the northwest, gusts may increase similar to
what we saw yesterday. Long range ensembles continue to show
gusts up to 30-40 mph being possible during the afternoon.
Things look to quiet down Sunday and Monday ahead of an
approaching wave some time mid next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1206 PM CDT Tue Jul 1 2025

No significant weather expected throughout the period with light
winds from 5-10kts decreasing below 5kts overnight, returning to
5-8kts at 240-270 later in the period. FEW050 for fair weather
cumulus possible this afternoon, with a sub 20 percent chance of
-TSRA as RWF/MKT overnight. FEW250 is expected after 02z due to
 upper level smoke that should move through by 08-10z. End of
 period could see -TSRA added in future TAFs, but it remain
 condition on where/when the storms form tonight.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/
THU...VFR, chc -TSRA/MVFR late. Wind SE 5-10kts.
FRI...VFR, chc TSRA/IFR pm. Wind S 10-15G25-30kts.
SAT...-SHRA/MVFR, chc IFR. Wind W 5-10kts.

&&

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

&&

$$

DISCUSSION...BED
AVIATION...TDH