413
FXUS63 KMPX 052347
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
547 PM CST Wed Feb 5 2025

.KEY MESSAGES...

- Wintry weather expected for Wednesday, mainly light snow
  across central Minnesota and western Wisconsin, with periods
  of freezing drizzle possible over southern Minnesota.

- Very strong west-northwesterly winds expected Thursday. Gusts in
  excess of 45 mph are possible.

- Widespread accumulating snow likely on Saturday.

&&

.DISCUSSION...
Issued at 232 PM CST Wed Feb 5 2025

Latest radar imagery shows light banded returns developing over
MN early this afternoon. This activity is occurring due to low-
level WAA across the state. MnDOT cameras and surface
observations dont appear to show precip reaching the ground,
but this should change later this afternoon/evening as a
shortwave and accompanying jetstreak approach from the west.
Areal coverage and intensity of snow will grow as synoptic
forcing increases, mainly to our north and northeast (across FGF
and DLHs CWAs). But, our northernmost central MN into west-
central WI counties should be clipped by the heavier
precipitation as the system develops and travels east this
afternoon through tonight. In this region, snowfall amounts of
2-3 are expected, with localized areas possibly pushing 4. No
winter headlines are in effect, though at this time, as amounts
should just barely reach Winter Weather Advisory criteria and
should mostly impact more rural areas. Snowfall should decrease
to the south owing to weaker lift and areas of lower saturation
within the vertical profile. An inch or less of snow is expected
across most of south-central MN, through the Twin Cities metro,
and into the rest of our WI counties. Additionally, some
freezing drizzle is expected to mix in, especially across
southern MN where profile saturation is lost in the DGZ but
remains underneath within subfreezing air. Thus, the evening
commute will be slick with light snow and freezing drizzle
affecting the roadways. Precipitation should taper off from west
to east tonight, ending over our WI counties by sunrise Thursday
morning.

Thursday should be mostly dry with high temperatures only a few
degrees lower than today. The main weather concern will be west-
northwesterly winds that will increase throughout the day. The
12Z HREF shows the aforementioned system/trough deepening
tonight into Thursday as it moves into the Upper Great Lakes.
Immediately in its wake will be a strengthening west-
northwesterly LLJ (HREF has a jet max of 70-80 knots at 700 hPa,
50-60 knots at 850 hPa) that will move across the southern half
of MN into WI during Thursday. With forecast soundings showing a
well-mixed boundary layer Thursday afternoon, the very strong
winds aloft should easily be transported to the surface.
Sustained winds of at least 25-30 mph and gusts of 35-40 mph are
a good possibility for nearly all of our CWA. Of greatest
concern will be areas along the Buffalo Ridge, southern MN, and
into west-central WI where gusts periodically will reach 45-50
mph. Areas of blowing snow could also occur, particularly over
central MN into west-central WI where the greatest amounts fell
Wednesday night. Winds should slow during Thursday night as the
LLJ pushes east while lows fall to near zero and the upper
single digits.

Upper-level ridging crosses the Rockies and moves into the
central CONUS on Friday, causing dry conditions for our region.
Highs will again fall a few degrees compared to Thursday due to
continued CAA. Our focus then turns to Friday night/Saturday as
forecast models continue to show a good chance of accumulating
(to possibly significant) snowfall for our region. While a ridge
from the southern jetstream moves into the central CONUS, a
trough from the northern stream should sag south and tighten the
pressure gradient between over the Northern Plains. This should
cause a zonal band of snow to develop over the Dakotas early
Friday night and spread/travel east into MN and WI late Friday
night into Saturday. NAM and GFS both show PWATs of 0.35-0.45
over our counties during this time period, producing reasonable
QPF values of 0.3 to upwards of 0.6 for most of our area by
Saturday evening. With forecast soundings showing lift centered
within a very deep DGZ, snow ratios are expected to exceed
climatology. We currently have adjusted SLRs to be 15-18:1.
Multiplying the SLRs by the QPF results in nearly all of our CWA
receiving at least 4.5 of snow, with a +6 swath stretching
from somewhere in western MN east into west-central WI. Even
greater snowfall (+9) may occur within the heaviest areas of
the swath where more focused banding can develop. Again, it
seems likely that we will have at minimum our second largest
snowfall event of the season. The only factors potentially
holding this system back are the fast translation speed of the
snow band and the possibility of further shifts south in future
model runs. Have opted to not issue winter weather headlines at
this time (due to today/tonights snow) but expect them to occur
within the next 24-hours.

The forecast quiets down a bit for the first half of next week
in the wake of Saturdays trough. Temperatures look to remain
below normal with highs in the upper single digits to teens and
lows dropping to near or below zero. However, 500 hPa height
anomalies within the long-range ensembles favor the development
of a trough over the western CONUS/Rockies while a downstream
ridge is situated near the eastern seaboard throughout next
week. Synoptic pattern recognition signals that this usually
means the formation of mid-latitude cyclones somewhere over the
central CONUS. Thus, it seems like more opportunities for
snowfall are on the horizon once we get past Tuesday.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 547 PM CST Wed Feb 5 2025

A narrow band of snow is lifting north into central MN early
this evening and within it some LIFR conditions are occurring.
It will impact STC during the next few hours. Meanwhile, some
light echos across southern MN and surface obs indicate some
areas of freezing drizzle developing. Introduced some at MKT but
it`s possible it may expand farther north and east this
evening. An additional round of precipitation is possible late
this evening and early overnight, before winds shift west and
increase markedly while skies clear. Some sporadic gusts
greater than 40 kts are possible Thursday across MN.

KMSP...There could be some additional light bands that develop
on the southern fringe of the main band, but any light snow
early this evening will be brief and largely unimpactful.
Another round could arrive later this evening, bringing a little
light snow. Between the two snow rounds, cannot rule out a
little -FZDZ from the echos to the south. Will continue to
monitor radar trends along with surface obs.

/OUTLOOK FOR KMSP/
FRI...VFR. Wind W becoming N 5-10 kts.
SAT...MVFR/IFR/SN likely. Wind NE 5-10 kts becoming NW.
SUN...VFR. Wind NW 5-10 kts becoming SW.

&&

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

&&

$$

DISCUSSION...CTG
AVIATION...Borghoff