986
FXUS63 KMPX 281949
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
249 PM CDT Sat Jun 28 2025

.KEY MESSAGES...

- Storms expected to develop over west central MN late this
  afternoon and track south and east from there through the
  night. Threat for very large hail and tornadoes will be
  greatest where storms initiate in western MN, with the threat
  transitioning to more of a wind threat through the night as
  lines develop.

- Next period of active weather looks to come at the end of
  next week, with a possible frontal passage for the Fourth of
  July.

&&

.DISCUSSION...
Issued at 249 PM CDT Sat Jun 28 2025

Although initially the unforecast MCS that came out of SoDak this
morning added a good deal of uncertainty to the forecast. The wind
field across southern MN says that it`s impacts on the atmosphere
were pretty minimal, with the main impact coming from its cloud
cover slowing down diurnal warming. West of the cloud cover, there
is a zone of enhanced WAA & isentropic lift near the h7 level that
is producing accas across western into central MN that`s trying to
produce some convection as well, though this looks to remain
elevated and continue to struggle and will not be a part of the main
show expected for later today. As for the main show, that is
expected to kick off quickly between 6pm and 8pm out in the region
from Morris over to Mille Lacs. A slight delay in initiation thanks
to the morning MCS. This is on the nose of an impressive CAPE
gradient, where mlCAPE should be maximized in the 4000-5000 j/kg
range. The highest CAPE values will be capped, but it`s just north
of the cap where storms will blow. Once they go, they`ll go fast
given the instability. Forecast hodographs do have a clockwise
curve, but they`re pretty short, indicative of the modest flow at
best. This high CAPE/low shear environment will favor multi-cell
clusters with occasional supercell structures. At initiation,
we`ll have the greatest threat for very large hail and brief
tornadoes, but these will quickly congeal. This will likely
result in one or more forward propagating MCSs that will pose a
primarily wind threat through the rest of the night, but
confidence is low on how any MCSs will evolve.

The uncertainty for Sunday starts right away, besides any remnants
from tonight`s MCS(S), we`re also seeing several CAMs that show yet
another MCS coming out of SoDak late tonight into Sunday morning.
This MCS would come from the storms we`re starting to bubble up in
northeast CO, with that energy heading for southern MN Sunday
morning. How big of a threat this activity will pose to southern MN
will come down to just how robust convection becomes over
western/central SoDak tonight. For the rest of Sunday, we`ll see a
very weak and diffuse wind shift work across MN during the
afternoon, with upper 60/lower 70 dewpoints in place. This will
result in a diurnal uptick in storms again Sunday afternoon across
eastern MN, but given the weak flow, the severe threat looks pretty
low for Sunday, with an isolated severe storm possible. The only
thing that could change this idea is if we get robust convection
coming out of SoDak that kicks off an MCV that could serve as a
focus stronger storms over southeast MN and western WI during the
afternoon.

Monday will be pleasant, but we`ll have the upper trough currently
over Alberta coming through during peak heating. Cooler temps aloft
will allow for the development of some scattered diurnal showers
Monday afternoon, with the greatest rain chances north of I-94.
Rising heights behind this trough will finally bring as a for sure
dry day on Tuesday.

For Wednesday and beyond, confidence in the forecast diminishes
considerably, with quite a bit of spread still present in the models
with how quickly moisture returns to the upper MS Valley. Looking at
the EPS, it currently favors a trough/frontal passage on Friday,
timed absolutely perfectly for all those afternoon and evening
Fourth of July celebrations you may have planned. No need to cancel
plans yet, but if you do plan on being out and about to celebrate
the Fourth, it would be a good idea to keep an eye on the forecast
in the coming days.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1254 PM CDT Sat Jun 28 2025

Although morning convection has added a bit of uncertainty to
this forecast, it looks like it`s impact on destabilizing the
atmo is going to be pretty minimal today. The main change to the
going TAFs was to delay the TS mention by a couple of hours at
terminals. Current expectations are that storms will rapidly
develop out by AXN between 23z and 01z, quickly building into
the STC area. After that, confidence diminishes as to how the
storms will evolve. A line of storms is certainly plausible, as
most CAMs show, but how quickly that forms, how fast it goes and
so on has little confidence at the moment, so outside of AXN &
STC, kept TS mention to PROB30s. One thing to watch is we do
have a band of accas right now where 700mb temp advection is
maximized in western MN and we may see some isolated TS develop
within this band of WAA before the main show gets going. Late
tonight into Sunday morning, we could also have a complex coming
out of SoDak and heading for southern MN, though confidence on
this potential shra/ts area is even lower than what we have for
this evening. Bottom line, look for amendments and continued
changes with 00z TAF update.

KMSP...Main impact from -RA moving over MSP at the start of the
period is it looks to delay the main TS threat for later this
evening, which should push the potential for strong to severe
storms out beyond the evening push for tonight. Dewpoints will
remain in the upper 60s through Sunday, with a weak boundary
coming through Sunday afternoon, this boundary will have the
potential to spark more shra/tsra Sunday afternoon, which is why
we added the second prob30 for TS to the 18z TAF.

/OUTLOOK FOR KMSP/
MON...VFR. Wind NW 10-15G25 kts.
TUE...VFR. Wind NW 10-15 kts.
WED...VFR. Chc TSRA. Wind SW 5-10 kts.

&&

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

&&

$$

DISCUSSION...MPG
AVIATION...MPG