Chaska, Minnesota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

656
FXUS63 KMPX 271746
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1246 PM CDT Fri Jun 27 2025

.KEY MESSAGES...

- After a busy few days, much quieter and drier weather today.

- Another period of active weather starts tonight into the
  weekend with strong to severe storms possible.

- Much hotter on Saturday with heat index values returning to
  the 90s.

&&

.DISCUSSION...
Issued at 310 AM CDT Fri Jun 27 2025

Today and Tonight... Lingering moisture and cooling diurnal
temperatures has allowed for low stratus and fog/mist to
persist. There is also enough broad synoptic forcing from the
shortwave that there is also some drizzle, mainly in western
Wisconsin, this morning. As temperatures rise after sunrise this
low stratus drizzle/fog will clear. With high pressure moving
in we should even see the sun for part of the day today,
allowing temperatures to warm up into the 70s. This brief
period of nice weather will not last though, as a return to
more unsettled weather arrives tonight. A favorable convective
environment with steep lapse rates, low level moisture, and
instability will be present over the Dakotas later today. This
should lead to convective development to our west. These storms
will track across the Dakotas and into Minnesota tonight. For
this reason SPC has a slight risk in western Minnesota. As the
evening goes on low level shear should improve along the nose of
the low level jet and allow for the formation of supercells. If
supercells form they could be long lived and track deeper into
Minnesota. The other potential for Minnesota impacts would be if
the cells can grow upscale into an MCS, which is shown in some
CAMs such as the 06Z HRRR. Overall a cap will make CI unlikely
over Minnesota, but elevated instability and favorable shear
will allow convection from the Dakotas to maintain strength.
Severe threats would depend on convective mode with wind the
main risk for an MCS with wind and hail for any discrete cells.

This weekend... As Friday`s high moves out a warm front will
pass through the Upper Midwest this weekend. This warm and moist
air advection will drive heat index values up into the 90s on
Saturday. So not the 100s we saw a week ago, but still quite
hot. This moist, unstable airmass with frontal forcing and a
broad trough will provide a favorable environment for
thunderstorms. This has given us a slight risk from SPC and a
marginal ERO from WPC. Storms appear most likely in the evening
to early overnight hours. A very unstable airmass with upwards
of 4000 J/kg of CAPE, sfc-3km SRH over 300 m2/s2, and
precipitable water values of over 1.75" all suggest an
environment primed for deep convection. In this environment
supercells would be possible and therefore= all severe threats
possible. The biggest question now is where in the broader risk
area will CI occur? This will be a key focus of mesoanalysis as
this period approaches. By Sunday we should be on the back side
of this system, which will bring down heat index values and the
severe threat. We will still see some synoptic support for
additional rain, especially early in the day.

Next week... Higher pressure once again to start the week with
Monday and Tuesday looking like nicer, sunnier days with
max temperatures near 80. By the middle of the week the active
weather looks likely to return. Global ensembles all have QPF in
this period however amounts, location of QPF, and timing all
still vary among membership. So it remains too early for many
details on this beyond a Wednesday/Thursday timeframe for the
next round of activity.

&&

.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...NDC
AVIATION...BPH