185
FXUS63 KMPX 281826
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
126 PM CDT Mon Sep 28 2026

.KEY MESSAGES...

- Dense fog ongoing this morning will begin to dissipate by 9-10am.

- Rain likely beginning Tuesday with chances lingering into
Wednesday, especially in southern MN.

- Temperatures near to just above average through next week.

&&

.DISCUSSION...
Issued at 300 AM CDT Mon Sep 28 2026

Dense fog is the main story this morning thanks to calm winds and
relatively warm dew points, which has allowed temperatures to
immediately crash down to dew points resulting in significant
radiation fog. Nighttime microphysics satellite imagery shows a bank
of stratus stretching across portions of southern MN with the dense
fog forming quickly as soon as the cloud cover retreats, and as of
around 230am local time the fog has become so dense in spots that it
is widespread within the satellite imagery as well. With the fog
incredibly dense, it will also take awhile to burn off this morning
as temperatures will be very slow to rise due to lack of solar
insolation as well as being past the autumn equinox meaning our sun
angle is becoming weaker by the day. Once the fog burns off, we
should see temperatures rebound quickly with highs today in the
upper 60s to low 70s which is just a touch above average for this
time of year.

The leading edge of potential rain showers arrives overnight tonight
into early Tuesday as a surface low begins to develop along the
leading edge of an approaching trough, reaching eastern Minnesota by
the late morning to early afternoon and continuing to spread
eastwards later in the day. A strong Canadian low will spin up late
Tuesday into Wednesday and when combined with the boundary already
over the area from the initial weaker surface low, could result in
some training rain showers and potential localized flooding. At this
point the most likely area for training rainfall would be
south/southeast Minnesota into western Wisconsin, however over the
last 24 hours guidance has trended slightly northwards compared to
the last few days. As a result of this northward shift within
primarily the GFS/GEFS, the NBM QPF forecast has also increased with
the highest rainfall amounts over southern/southeast Minnesota and
western WI on the order of 2 or more inches. While the exact numbers
are still changing with each forecast package, the overall trend is
the thing to monitor for now. As far as convection is concerned,
forecast soundings show a small sliver of instability which could
result in some rumbles of thunder, however the profile is very
saturated with very high PWATS indicative of a rain loaded
atmosphere as opposed to a convective one. We are also still
relatively warm which will result in a higher freezing level, and
with our lack of instability we may not see an individual updraft on
a mesoscale strong enough to produce much in the way of lightning.
We expect most of the area to see at least a half inch of rainfall
with the lowest amounts in western Minnesota before the boundary
stalls into Wednesday over the south/eastern part of our area.

Behind the departing system towards the late week and next weekend,
temperatures will cool down with highs falling back into the low to
mid 60s with a lack of other significant rainfall on the horizon.
Ensemble guidance shows relatively little in the way of
precipitation until at least Sunday of next weekend, and even then
it is a minority of ensemble membership within the GEFS/EPS showing
any precip at all, let alone measurable. This continues throughout
the rest of the period with no significant precipitation signals
throughout, rather we stay in the 60s for highs and upper 40s to low
50s for lows without any significant weather systems through the
rest of the period.

&&

.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 101 PM CDT Mon Sep 28 2026

12Z MPX sounding showed a strong inversion at h85 sitting atop
our low level moisture layer. This setup limits the mixing,
which is why we`ve seen the fog lift into a stratus/stratocu
deck with limited clearing. This statocu deck will remain in
place through the night, though will lift to high MVFR/VFR
levels. We will remain dry much of tonight, but as we get toward
6am Tuesday morning, rain showers will be moving into western
MN. Instability is limited, so TS threat is there, but not high
enough to include any TS in the TAFs for now. Timing of showers
in MN was based on a consensus of short term models from the
NBM, which is a bit slower than the 12z HRRR, but dealt with the
onset uncertainty with prob30s before prevailing precip. Also
coming with the precip will be a return to MVFR or lower cigs
for anyone that happens to go VFR tonight.

KMSP...CIGS continue on a rising trend and we expect MSP to be
VFR by sunset. We will go back to MVFR on Tuesday, but right
now, that looks to be timed with the arrival of the rainfall. As
for rainfall arrival, we`re seeing the HRRR on the early side,
bringing in showers at 15z, with most of the other CAMs starting
showers more in the 17z/18z timeframe.

/OUTLOOK FOR KMSP/
WED...IFR, chc LIFR/FG in mrng then VFR. Wind SW 5-10 kts.
THU...VFR. Wind NW 10-15G25 kts.
FRI...VFR. Wind SE 5-10 kts.

&&

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

&&

$$

DISCUSSION...TDH
AVIATION...MPG