772
FXUS63 KMPX 310915
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
315 AM CST Fri Jan 31 2025

.KEY MESSAGES...

- Confidence increasing in a couple inches of snow across eastern
  Minnesota and western Wisconsin Saturday.

- Second round of accumulating snow possible across south central
  Minnesota Sunday into Monday.

- Much colder next week, with additional chances for light snow.

&&

.DISCUSSION...
Issued at 301 AM CST Fri Jan 31 2025

The late January thaw that yielded record setting warmth on Thursday
will take a step back today, as cooler Canadian high pressure builds
into the Upper Midwest. National water vapor analysis captures an
upper-low over the central Great Plains. Precipitation associated
with this system will remain south of the Minnesota/Iowa border, due
to suppression from the aforementioned area of high pressure. The
upper-low will weaken with eastern extent, such that cold advection
on the northwest side of the system is not overly impressive. Thus,
with only a wind shift and weak thermal advection, we expect another
day with above average highs in the mid 30s/low 40s along and south
of a line from Swift county to Rusk county (WI). Cooler temperatures
near the freezing mark are forecast for locations north of that
line.

Active weather returns this weekend, with a couple periods of
accumulating snow possible. A clipper system, currently moving
ashore in the Pacific northwest per water vapor imagery, is forecast
to advance across the southern Canadian provinces through Saturday,
before moving towards the Great Lakes by Sunday. The first window
for light snow will be on Saturday, as warm/moisture advection ramp
up in association with the eastward advance of a potent 50-60kt low-
level jet. Guidance has come into better agreement with the
positioning of a broad precipitation shield, driven by strong
isentropic ascent on the leading edge of the advancing system. No
major changes were made to the forecast with this cycle, as guidance
continues to point towards locations along and north of I-94 as
having the best potential for light accumulating snow (QPF
amounts ~0.1-0.2"+). It appears likely heavier QPF will remain
to the north across WFO Duluth`s forecast area. QPF amounts
taper to a few hundredths to the south and west of the Twin
Cities Metro. Our latest snowfall forecast features 1-3" north
of I-94 in eastern MN/western WI, with around an inch or so
along the interstate. The main window for accumulating snow will
be Saturday afternoon & evening. Dry antecedent conditions from
Friday introduce a level of uncertainty into just how far west
the 1"+ line of accumulating snow will be. I don`t want to go as
far as calling this a "boom or bust" scenario given the lower
end nature of the high end totals (~3"), however there are
outcomes where the column takes longer to saturate and snowfall
totals come in short of expectations across eastern Minnesota.
The highest confidence in the snowfall forecast is across our
western Wisconsin counties. One other item of note, we`ll need
to keep an eye on the western edge of the precipitation
Saturday, as forecast soundings are already hinting at the
potential loss of cloud-ice aloft as the jet axis shifts east.
This scenario would point towards lingering drizzle, which if
paired with a favorable thermal setup could create a freezing
drizzle concern. At this point the setup looks marginal for
freezing drizzle, but will be something to monitor heading into
Saturday evening.

The clipper system will move east across the northern Great Lakes on
Sunday. The resultant mid-level temperature gradient across the
Dakotas/Minnesota is forecast to tighten as cold air advection
increases on the backside of the departing upper low. This gradient
will be the focus for additional light snow chances to close the
weekend, especially when paired with an incoming mid-level impulse
captured on the 00z guidance. NBM`s PoPs between 20-30% Sunday into
Monday seem quite reasonable at this time, as confidence is low in
snowfall duration, coverage, and amounts. However, it should be
noted that this type of thermally driven snowfall historically has
"sneaky" potential for high efficiency given the frontogenetic
element. Essentially, think of this setup as a linear, relatively
narrow band of snow that will have the potential for higher
rates should the pieces come together. Whether this is realized
across the Dakotas, Nebraska, Minnesota, Iowa is still uncertain,
given potential suppression of the forcing due to the exiting
clipper system. All this to say keep an eye on the end of the
weekend for another round of accumulating snow across southern
Minnesota.

Much colder air arrives for the start of the work week. The NBM
features highs in the upper teens/20s, along with lows in the
single digits to lower teens through next week. The unsettled
weather pattern will continue through the first week of
February, with growing potential for a more defined storm system
to move across the Midwest during the Tuesday-Thursday
timeframe. Variance in the global guidance leads to low
confidence in any one solution, though a blend of the
deterministic solutions would point towards the potential for
mixed ptype with this storm system. Objectively this appears
curious, given the expected thermal scenario, however a more
northern track would bring the warm sector north (thus likely
warmer temperatures than the current NBM), so again it will be
something to watch. The extended forecast remains active, with
signals for more storm systems across the central CONUS heading
into the middle of February.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1056 PM CST Thu Jan 30 2025

Not much has changed with the 6z TAFs, with the potential there
for some MVFR cigs Friday afternoon, but the 00z HREF continues
to run with low probabilities for MVFR cigs, with those
probabilities highest back across southern NoDak and northern
WI. We will see NNE winds increase in strength, with some gusts
up around 20 kts expected. Friday evening, winds will turn over
toward the east as a mid level deck of clouds overspreads the
region.

KMSP...Since the 00z TAFs, the MVFR cig potential for Friday
afternoon has decreased further, so feeling more confident in
VFR conditions prevailing this period.

/OUTLOOK FOR KMSP/
SAT...MVFR cigs likely. Chc IFR/-SN. Wind SE 10-20G30 kts.
SUN...MVFR cigs likely. Chc IFR/-SN. Wind NW 10-15 kts.
MON...VFR. Wind NW 10-20 kts.

&&

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

&&

$$

DISCUSSION...Strus
AVIATION...MPG