963
FXUS63 KMPX 272008
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
308 PM CDT Fri Jun 27 2025

.KEY MESSAGES...

- A thunderstorm complex is expected to move through the area
  early tomorrow morning. Damaging wind gusts are possible.

- Another round of thunderstorms is expected late tomorrow
  afternoon & evening. All modes of severe weather are possible,
  along with heavy rain & localized flooding.

- Hot & humid Saturday with heat indices up to 100 degrees.

&&

.DISCUSSION...
Issued at 158 PM CDT Fri Jun 27 2025

A very active weekend lies ahead with multiple rounds of strong
to severe thunderstorms and locally heavy rainfall expected.
Severe thunderstorms will develop across the Dakotas,
eventually merging into a thunderstorms complex overnight. This
complex of thunderstorms will move into western Minnesota during
the overnight hours (2-4 AM) and move gradually southeastwards
through the morning, reaching the Twin Cities/I-35 corridor by
sunrise (5-7 AM) & eventually dissipating over southeast
Minnesota/western Wisconsin by mid-morning. Damaging wind will
be the main severe threat with this thunderstorm complex, and
the threat will be highest across western Minnesota where
500-1000 J/kg of surface- based CAPE will be present overnight.
Instability is weaker farther east, meaning the complex should
begin to weaken through the morning across eastern Minnesota &
western Minnesota, but a few sporadic damaging wind gusts still
can`t be ruled out. Heavy downpours are likely with quick
rainfall amounts of around an inch, but the flooding threat
looks minimal due to the progressive motion of the thunderstorm
complex.

After the thunderstorm complex dissipates during the morning, a
warm front will move northwards through through the area &
advect in much higher dew points out of Iowa. Afternoon
temperatures will depend on how quickly clouds clear out from
the morning thunderstorms, but most locations should warm well
into the 80s & into the 90s across southern & far-western
Minnesota. Dew points near the mid 70s will allow for heat
indices of 95-100 degrees, possibly higher across southern
Minnesota if daytime heating is maximized there. This will allow
for an very unstable environment to build over Minnesota &
Wisconsin as Surface-bnased CAPE values are forecast to reach
4000 J/kg across southern Minnesota and far-western Wisconsin.
However, temperatures aloft will also be warmer over this
environment, with 700 mb temperatures of 10-12 C indicating
strong (but not not unbreakable) capping will likely be in place
into the evening.

The main area of interest for thunderstorm initiation Saturday
afternoon is north of this capping, across central Minnesota
where the environment will be less explosive ("only" 2000-2500
J/kg SBCAPE) but much more conducive for storm development with
cooler temperatures aloft. Furthermore, one or more boundaries
will likely be left over from the morning convection, likely
acting as an initiation point wherever they set up across
central Minnesota by late afternoon. Dep shear values will be
seasonally strong for late June with 30-40 kts of deep shear
overlaying the explosive environment, meaning thunderstorms
will rapidly intensify after they initiate & have the potential
to become supercellular quickly. All modes of severe
thunderstorms would be possible with these initial supercells,
with damaging wind gusts likely the main hazard followed by the
potential for a few tornadoes & large hail. However, the lack
of capping over central Minnesota also means that thunderstorms
will likely become widespread quickly after initiating,
resulting i these initial supercells merging into one or
multiple clusters of thunderstorms. Once these clusters develop,
the severe threat becomes predominately damaging wind along
with an increasing threat for torrential rain & localized
flooding. Confidence is still low in the details for when and
where exactly this evening round of severe weather will occur,
as we`ll need to determine where the mesoscale boundaries set
up during the afternoon. Somewhere over central Minnesota
between 4-6 PM looks to be the general consensus for the
initial supercell threat, with these storms quickly merging
into clusters of storms and moving eastwards/southeastwards by
6-8 PM, with the damaging wind threat continuing into western
Wisconsin through 10 PM-midnight. Hard to say where exactly
these clusters will move once they develop, as storm-scale
propagation will take over & they will track along any existing
boundaries, but think the overall severe threat is highest
north of a line roughly from Marshall- Northfield-Eau Claire.
Additional scattered thunderstorms look likely to develop
during the overnight hours as the low- level jet interacts with
remnant boundaries, but these look to mainly be rain-makers
with an overall low threat for any severe weather. The possible
exception could be across far-southern Minnesota, where a few
high-resolutation models depict a thunderstorm complex
developing across eastern South Dakota & impacting at least
portions of southwestern Minnesota.

Temperatures return back to more seasonable values Sunday as a
cold front moves in behind the storms Saturday night. Another
round of thunderstorms will likely develop along the front
during the afternoon, but models differ on the timing &
location of the front across central Minnesota. Any threat for
strong to severe thunderstorms would be limited to portions of
western Wisconsin, but the overall the threat looks to be
mainly east of our area. Northwest flow then develops aloft &
continues through midweek, keeping us generally dry & near-
normal to slightly below-normal for temperatures. The next round
of active weather comes Thursday into the weekend as the flow
becomes stronger aloft & a few disturbances develop in the
northwest flow aloft.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1232 PM CDT Fri Jun 27 2025

MVFR conditions will continue through the afternoon hours, then
expect improvement to VFR as clouds scatter this evening. Wind
shift from the N/NW to SE by late afternoon, generally around 5
to 10 kts. Latest hi-res guidance brings a line of storms
through late tonight into early Saturday morning. While there is
confidence we`ll see a complex of storms move into MN overnight,
the exact track is less certain. I`ve opted to go with PROB30s
given the uncertainty on track/coverage of the thunderstorm
complex. Impacted terminals can expect a brief dip to MVFR/IFR
conditions while the storms move through.

KMSP...Most likely timing for storms would be around early to
mid morning Saturday. PROB30 highlights the best period for the
complex to move through. An additional round of thunderstorms
are possible Saturday evening that may require another PROB30
with the 00z TAFs.

/OUTLOOK FOR KMSP/
SUN...MVFR/RA likely, chc TSRA/IFR. Wind SW 5-10 kts.
MON...VFR. Wind NW 10-15 kts.
TUE...VFR. Wind NW 10-15 kts.

&&

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

&&

$$

DISCUSSION...ETA
AVIATION...BPH