Chaska, Minnesota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

131
FXUS63 KMPX 021202
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
702 AM CDT Wed Apr 2 2025

.KEY MESSAGES...

- Another round of heavy precipitation to develop over western
  into central Minnesota this morning into the afternoon.
  Additional heavy snow is likely, with an additional 6+ inches
  of snow possible.

- An extended period of quiet weather sets in for the end of
  this week into next week, with below normal temperatures
  through early next week.

&&

.DISCUSSION...
Issued at 341 AM CDT Wed Apr 2 2025

Our multifaceted winter storm continues this morning, though
overnight, we`ve been in a lull between the first wave of the storm
(the strong WAA band of snow we saw Tuesday evening) and the second,
more prolonged phase of the storm, which will be the deformation
precipitation to the northwest of the surface low associated with
the passing of the mid level low. Surface analysis at 3am showed a
surface low beginning to consolidate over eastern KS. This will be
near Mason City, IA at 18z, Hayward, WI at 00z, and Isle Royale by
06z. Aloft, an h7 low is forecast to be near Madison, MN at 18z,
then west of Duluth at 00z. This h7 low will be deepening during the
day as a TROWAL moves across Iowa toward western WI. Along and west
of this h7 low track, a strong deformation band of precip is
expected to develop. This is a Spring system, which means p-type
will be a challenge. As this deformation band is developing this
morning, there will still be a warm nose aloft, which means the
potential for a mix of rain, freezing rain, sleet, and snow will
possible as this band is developing over west central MN. A quick
look at forecast guidance shows that the freezing rain threat really
looks to be terrain driven, with the greatest icing potential be
along the eastern edge of the Buffalo Ridge, which fall just
southwest of the MPX area. As this deformation band really gets
going this morning, we`ll dynamically cool the warm nose, which gets
us back to a rain/snow question. Once again, the difference between
this being 33 degrees and heavy snow or a 34 degree downpour is
razor thin. The potential is certainly there for snowfall to get out
of control, with 0.75" to 1" of QPF expected within the most intense
portion of the deformation band. The main question is just how much
of that liquid gets dumped into the snow bin, verse the rain,
freezing rain, or sleet. Where it looks most likely for things to
remain snow is along and northwest of a line from Morris, to
Alexandria and Motley. Here, it`s possible that we could see
additional snowfall amounts from just today push 10", though it`s
hard to say just how much snow we`ll be able to achieve given the
melting and compaction we`ll see from the snow falling during the
day. Output from various models for their modeled snow depth shows
that falling in the 6-10" range within the heaviest band of snow,
which seems reasonable given the melting and compaction we`ll see.

As for winter headlines, we reoriented those to better capture
expectations of impacts expected with phase 2 of the storm. The
first change this required was extending headline end times out into
tonight, with this deformation band not expected to start winding down
until this evening. We ended up downgrading Kanabec and Mille Lacs
county from the Warning into an Advisory, with the phase 2
deformation band really remaining northwest of these counties. We
then added Stevens and Pope counties in west central MN to the
Warning to add a little southern buffer to the warning in case we
get some over achieving with that snowfall band. An advisory was run
to the south of the Warning across Benton and Stearns down to
Yellow Medicine and Lac Qui Parle counties. Yellow Medicine and Lac
Qui Parle also have the greatest threat for some icing this morning
before the warm nose breaks down.

So for the non-winter side of this storm, we expected an area of
showers, and possible a rumble of thunder or two, to accompany the
low as it track across southeast MN into western WI. Areas along and
near the surface low track will also get treated to the dry slot, so
this will cut down considerably on rainfall amounts for eastern MN
and western WI, with additional QPF from this storm only expected to
be around 0.25". Finally, as a location gets to the south of the low
and into the dry slot, WSW winds will increase in strength
considerably. The strongest winds are expected late this afternoon
and evening across northern Iowa into southeast MN, where sustained
winds around 30 mph and gusts to 45 mph will possible. We held off
on any wind advisory headlines for now, though this potential will
need to be addressed again through the day.

After today, we still look to enter a 7-10 day (at least) stretch of
quiet weather. By the end of the week, a ridge will build out of
the eastern Pac and into northwest Canada. This will put us into
northerly flow with surface high pressure. The coldest air of this
pattern looks to come Monday, when h85 temps will bottom out in the
-10c to -15c range. This will likely mean lows in the teens and 20s
Monday/Tuesday of next week, with highs on Monday likely struggling
to hit 40. The good news though is that as we hit the middle of next
week, the western ridge will have flattened out and shifted east,
which will bring us a mild Pacific airmass, with highs returning to
the 50s and 60s for the second half of next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 647 AM CDT Wed Apr 2 2025

Phase 2 of this system is just beginning to ramp up this
morning. It`s starting with the batch of drizzle (much of it
fzdz) across central MN, though this is expected to fill in with
rain and snow over the next couple of hours. RWF/STC look to be
near the rain/snow line, with AXN likely to see heavy snow, with
rates of 1" per hour between 16z and 22z, when all is said an
done, they could end up with near 10 inches of snow. It`s rain
for MKT/MSP/RNH/EAU. These sites all have the chance for the
thunderstorm as well, though only have a TS mention at MKT for
now. Surface low this afternoon will pass over/near MSP and RNH
and as it passes, both airports will see a rapid change in wind
direction from the east over to the southwest. For cigs, they
will continue to lower as the low approaches, though we may not
be fast enough to bring cigs up once a terminal gets south of
the low and switches to WSW winds.

KMSP...Surface low look to pass just east of MSP around 20z or
21z. As a result, right around 21z, we expected winds to shift
from an easterly over to a westerly direction, with a switch
from the 12z over to the 30s likely needed around 21z.

/OUTLOOK FOR KMSP/
THU...MVFR cigs in mrng. VFR in aftn. Wind NW 10-15kts.
FRI...VFR. Wind E 5-10kts.
SAT...Chc MVFR cigs early. Wind NW 10-15G25kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Winter Storm Warning until 1 AM CDT Thursday for Douglas-
     Morrison-Pope-Stevens-Todd.
     Winter Weather Advisory until 1 AM CDT Thursday for Benton-
     Chippewa-Kanabec-Kandiyohi-Lac Qui Parle-Mille Lacs-
     Stearns-Swift-Yellow Medicine.
WI...None.

&&

$$

DISCUSSION...MPG
AVIATION...MPG