506
FXUS63 KMPX 180453
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1053 PM CST Mon Nov 17 2025

.KEY MESSAGES...

- Rain and snow develops this evening across southern Minnesota
  and overnight across west central Wisconsin.

- Heavy snow rates are possible, but temperatures aloft remain
  critically close for either a rain/snow mix or mostly snow.

- Sharp cutoff to the precipitation on the northern edge is
  leading to lower confidence for the Twin Cities metro.

- Higher confidence for snow accumulation exists along a line
  from Redwood Falls to the southern Twin Cities Metro and
  towards Eau Claire. If precip type becomes mostly snow, 3 or
  more inches are possible. A Winter Weather Advisory has been
  issued for the risk of heavy rates and higher amounts. There
  is a conditional risk for hazardous travel conditions during
  the Tuesday morning commute.

&&

.UPDATE...
Issued at 858 PM CST Mon Nov 17 2025

The 00z guidance has mostly arrived and continues to show what
is an ongoing complex forecast as even within the short-range
CAM guidance there are significant model differences mostly in
the snow amounts as well as the other p-type amounts. Sleet
seems to be the predominant alternate p-type besides rain/snow,
which makes sense given the forecast soundings as we do not have
a true warm layer to melt falling snow that could refreeze once
surface temperatures cool down, thereby crossing out freezing
rain as a possibility. Freezing drizzle (which is an entirely
different physical process) also seems to be absent given good
saturation within the DGZ and little chance of losing cloud ice.
Thus, we continue to run with the forecast being rain dominant
through 05-06z, with a rain/snow mix that struggles to
accumulate for an hour or two, followed by the primary snow
producing timing for a few hours leading up to sunrise and
including the morning commute. The main question is still how
far north the snow line sets up, with guidance continuing to
keep the heaviest snow just south of the Twin Cities Metro,
stretching from roughly Redwood Falls to the southern borders of
Scott/Dakota counties to Eau Claire. Forecast soundings are
still showing a thermal profile near the freezing line as things
saturate, thus aggregate snowflakes that quickly accumulate
remain possible within the primary snow band, however outside of
this band where forcing is weaker we may not have the lift to
produce enough snowflakes to overcome surface temperatures that
will be in the mid 30s.

As of the 03z observations, we finally have our first reports
of rain reaching the ground in Albert Lea as dew points have
slowly increased with lighter showers resulting in VIRGA, and
higher echoes moving into southern MN could mean some isolated
thunder as well. Farther to the north, dew points in Mankato and
northwards are still in the 20s, thus we have to continue to
wait to saturate before precipitation will reach the ground
despite the weak echoes on radar. The overall messaging
continues to be to plan ahead for a relatively slow morning
commute within any of the areas expecting to see precipitation,
with roads expected to at least be wet if not partially covered
in slushy snow. Thankfully without dropping more than a degree
or two below freezing, a flash freeze scenario from the rain
after it turns into snow seems unlikely with the exception being
if any colder air pools underneath bridges or overpasses that
tend to ice up quicker.

&&

.DISCUSSION...
Issued at 248 PM CST Mon Nov 17 2025

A very complex forecast is unfolding for tonight and Tuesday
morning. A compact upper low over the central Plains will
continue east tonight and reach Iowa Tuesday morning. A narrow
band of rain is developing across southern SD, with
thunderstorms also ongoing in southeastern SD. This band will
lift north for the rest of the day into the evening and become
better developed by the time it reaches southern MN. Anomalously
high pwats of nearly 0.9 inches are advecting north and will
wrap to the northern side of the system tonight. Strong
frontogenetic forcing and conditional symmetric instability will
be present in the DGZ later this evening. The band will mature
during this time and should lead to heavy precipitation. It will
likely remain quite narrow and models are still showing small
run to run differences in its latitudinal extent. These small
differences may not normally lead to significant outcomes, but
given that the band will be narrow and there will be a very
sharp cutoff of the precipitation on its northern flank, this is
leading to much lower than normal confidence along a line from
Canby, to the Twin Cities metro, to the Eau Claire area. Little
is expected north, and about 0.75 inches of liquid equivalent
precipitation is expected just about a county to the south.

Forecast soundings from just about every model continue to
exhibit an isothermal profile at 0C from the surface to ~8 kft.
This means that a 1 degree variation one way or the other will
result in all rain or all snow. Given the QPF, expected precip
intensity, and most precip falling overnight, an all snow
scenario would result in several inches. Continued to highlight
rain this evening turning to a mix of rain and snow overnight.
Conceptual models favor more snow, but the very high pwats may
limit the atmosphere`s ability to cool much more than freezing.
Therefore, equal parts of the QPF forecast have been distributed
to the rain bin and the snow bin, yielding roughly 2 or 3
inches of snow in the advisory area. In addition, the favorable
dynamics will be highly efficient in producing dendrites, and as
those dendrites descend through a deep isothermal layer around
freezing they will continue riming and form aggregates. These
aggregates could be large and effective at quick accumulation.

Since this is the first snow of the season and will be
occurring during the morning commute, we are a bit more liberal
with issuing a Winter Weather Advisory. The northern half of the
metro may not see much or any, but the southern half may. The
core metro will need to be considered in future updates, but
given such a low confidence forecast with the cutoff very close,
left out Hennepin, Ramsey, and Washington counties for now. The
rain and snow will wrap up mid morning. Clearing will take
place across central MN, but considerable cloud cover will
remain to the south.

For the rest of the period, a mild airmass and quiet weather
will prevail across much of the country through early next week.
PoPs have decreased with the system Wednesday night into
Thursday with precip likely remaining north.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1045 PM CST Mon Nov 17 2025

With the exception of RWF/MKT that are already seeing rain
showers by the start of the TAF period, we have delayed the
onset of -RA and by proxy -RASN at MSP/EAU as the line of
showers has been slow to push northwards. The scenario continues
to remain initial rain eventually transitioning to snow, with
RWF/MKT still the most likely to see accumulating snow with a
lower chance for MSP/EAU. STC/AXN/RNH should remain dry with
mainly mid level VFR CIGS.

For the locations where precip is possible, this may end up
being a TAF period with multiple AMDs as high resolution
guidance has performed poorly thus far both in regards to timing
and intensity of precipitation, with intensity being lower than
expected so far a big deal when it comes to dynamically cooling
the atmosphere and increasing snow chances. Regardless, we do
expect MVFR if not IFR CIGS as the precipitation moves through,
with periods of IFR VIS due to precip as well.

KMSP...We have delayed the onset timing of -RA to 09z with a
weaker -RASN mix within the TEMPO from 11-15z based off how the
system has progressed so far this evening. Dew points are a
large concern, with surface dew points still in the mid teens at
MSP which is a significant amount of low level dry air to
overcome in order for precipitation to start reaching the
ground. Unless the strongest portion of the band moves over the
airport, it is looking less likely to see mixed rain/snow and
impacts from snow, with anything but the strongest portion of
the system going to result in a lot of the precipitation
evaporating/sublimating before reaching the ground due to the
very low dew points. We will have to pay close attention to the
line of showers as they approach Scott/Dakota counties
overnight, with short term AMDs possible based on how the radar
looks within the first 6-8 hours of the period.

/OUTLOOK FOR KMSP/
WED...MVFR, IFR CIGS possible. Wind S 5-10kts.
THU...MVFR, -SHRA possible. Wind SW to NW 5-10kts.
FRI...VFR. Wind NW 5kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Winter Weather Advisory until 9 AM CST Tuesday for Brown-
     Carver-Dakota-Le Sueur-McLeod-Nicollet-Redwood-Renville-
     Rice-Scott-Sibley-Yellow Medicine.
     Winter Weather Advisory until 11 AM CST Tuesday for Goodhue.
WI...Winter Weather Advisory until 11 AM CST Tuesday for Eau Claire-
     Pepin-Pierce.

&&

$$

UPDATE...TDH
DISCUSSION...Borghoff
AVIATION...TDH