Foreston, Minnesota Weather Forecast Discussion

749
FXUS63 KMPX 211143
AFDMPX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
643 AM CDT Sun Sep 21 2025
.KEY MESSAGES...
- Isolated showers and storms this afternoon/evening, a small
  chance for strong/severe storms mainly in southern MN.
- Mild temperatures through the period with little weather after
  showers end on Monday.
&&
.DISCUSSION...
Issued at 627 AM CDT Sun Sep 21 2025
The upper level low which has dominated the weather pattern over
the last few days continues to be visible on GOES-E water
vapor imagery, centered around eastern NoDak and northwestern MN
border as of around 245am. This feature is expected to continue
to migrate eastwards throughout the day, setting up another
round of isolated showers and potential thunderstorms as a
strengthening 850-700mb jet introduces lower level forcing later
in the day. Forecast soundings from the RAP/NAM show around
1000 J/KG MLCAPE around 21z near RWF with low to moderate deep
layer shear and lapse rates, such that isolated storms are
possible. There is enough instability and shear to produce some
stronger updrafts, with the primary question being if anything
holds together long enough to sustain any sort of severe weather
threat. SHARPpy sounding analogs show a few instances of severe
hail with this kind of setup, however it looks to be a case of
one or two storms that become strong enough rather than the
majority of showers and storms that appear. Given all of this
together, the upgrade to a SWODY1 marginal risk that includes
the southern Twin Cities metro seems like a good call, with hail
being the only real threat as low level shear looks rather weak
and PWat/DCAPE don`t support a significant wind threat. The
tornado threat is non-zero but quite low, right now below the 2%
threshold that SPC uses within their outlooks, however there is
some possibility there given the favorable hodograph shape and
low LCL height, however any sort of funnel cloud or tornadic
threat would likely be limited to the bottom end of the scale in
terms of strength due mainly to the weakness of potential
updrafts overall. The peak timing for this threat is generally
late afternoon through the evening, with lingering showers and a
few storms overnight that will be much weaker as the forcing
weakens.
Isolated showers remain possible on Monday as the upper level
low migrates over Lake Superior with weak shortwave energy
continuing to rotate around the feature, with the most likely
areas looking to be along I-90 in southern MN and in western WI.
These will be nothing more than some nuisance showers with
limited thunder potential due to a slightly cooler airmass and
limited instability. Quieter weather looks to be in store the
rest of the week as the upper level low continues to weak before
moving towards the southern Great Lakes, as northerly flow
returns aloft and weak surface high pressure produces general
subsidence across the region. Ensemble guidance beyond Monday
shows very sparse membership producing any kind of
precipitation, and with weak subsidence we are likely looking at
just some fair weather cloud cover. This will also bring some
chances for fog as we radiate efficiently overnight, with dew
points remaining in the low to mid 50s until at least next
weekend. This will make for comfortable weather overall as high
temperatures will stick in the low to mid 70s, with overnight
lows falling to dew points in the low 50s. Not quite into
typical Autumn weather quite yet, with the rest of September
looking mild and no airmass shift expected until we get into
October.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 627 AM CDT Sun Sep 21 2025
BKN/OVC coverage throughout this duration with mainly VFR decks
though the occasional MVFR/IFR level is near and for a couple
hours after sunrise. Best chance for any precipitation looks to
come mid-to-late afternoon into the evening hours for isolated
SHRA/TSRA. Though TS cannot be ruled out, have held mention at
SHRA for now due to low chances and very isolated nature of any
possible TS so will let radar trends and the upcoming KMPX RAOB
dictate the need to re-introduce TS in later TAFs. Model trends
do indicate another round of MVFR ceilings late tonight into
Monday morning, possibly fog should enough rain develop, so have
introduced that trend at the tail end of the TAFs.
KMSP...VFR conditions mainly expected throughout this duration,
with the best timing of precip looking to be early-mid evening.
Not expecting TS at this point, but it is a non-zero chance so
there is the chance it could be added to later TAFs.
/OUTLOOK FOR KMSP/
TUE-WED...VFR. Wind NE 5-10 kts.
THU-FRI...VFR. Wind NW 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...TDH
AVIATION...JPC

NWS MPX Office Area Forecast Discussion