Shakopee, Minnesota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

479
FXUS63 KMPX 231124
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
524 AM CST Mon Dec 23 2024

.KEY MESSAGES...

-  Chances for freezing drizzle are decreasing by the hour.
   Dusting of snow remains possible over the next few hours in
   central MN and western WI.

-  A warming trend will occur this week with highs in the low
   to mid 30s by Christmas and near 40 possible by later in the
   week.

-  Rain chances increase late week and next weekend.

&&

.DISCUSSION...
Issued at 314 AM CST Mon Dec 23 2024

As the models have been hinting at for the last day or two,
things continue to trend on the lighter side for precip this
morning. Additionally, onset time of any precipitation continues
to be delayed, lessening the chance for freezing drizzle.

Strong cold air advection ahead of the local vorticity max should
provide the forcing needed for a narrow west to east oriented band
of precipitation within the next hour or two in western MN. This
will progress to the Twin Cities and western WI around daybreak,
continuing to be very light in nature. The longer it takes for
precip to initiate, the lesser the chance for freezing drizzle. With
this in mind,forecast soundings support a scenario where there`s a
brief window of up to an hour where precip starts as a
sleet/snow mix in central MN before switching over to all snow
by the time things reach WI. 00z models have backed off a bit on
the amount of QPF (especially the NAM), so even less in the way
of snow is expected. Given the diminished icing threat and low
(if any) snowfall amounts, we`ll continue to run with the
Special Weather Statement for the wintry precipitation through
12Z, with no Winter Weather Advisory headlines planned. Travel
conditions could be slick in areas with precip, but overall low
impacts are expected this morning.

Another tricky aspect to this forecast is the location of the
stratus deck and how that will progress through the day. The reason
this makes things tricky is because conditions are ripe for
radiation fog to form overnight tonight. Where the stratus deck
remains, temperatures will be slightly warmer and fog will be
less prevalent. Where the stratus deck lifts or breaks up,
temperatures will cool more and fog will be more of an issue.
Our current forecast suggests patchy fog developing around 10PM
in western MN, lurking through 9/10AM. Southern MN and areas
around Eau Claire could also see some development around
midnight, but eastern MN and north along the I-35 corridor
should be in the clear due to higher cloud cover.

Hand-in-hand with the fog potential is Monday night`s low
temperatures. We slightly altered NBM Min Ts up where we
anticipate more cloud coverage and down where there should be
less. This means lows in the teens in western MN and in the low
20s in eastern MN and western WI. As temperatures will be well
above normal Wednesday onward, this is the last night with
forecast lows in the teens for 2024! Warmer air typically means
more moisture, and this week is no exception to that. Our
perturbed pattern will continue with several chances for
additional precipitation. The first of which arrives Friday,
when we will have highs in the upper 30s to low 40s. With those
temps, this is looking to be an all rain P-type event. Current
QPF across the area from Friday through Sunday is on the order
of a quarter to half inch of liquid. While that will be refined
in future forecast packages, it is enough of a signal worth
mentioning. Most should fall as rain, but once night falls, some
mixed precipitation cannot be ruled out. The second signal in
the extended forecast period arrives around New Year`s Eve.
Confidence remains low with regards to any details associated
with it, but with cooler temperatures returning, snow chances
will be reintroduced.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 519 AM CST Mon Dec 23 2024

We`ve maintained the status quo of a plethora of prob30 groups
for light snow within the early portions of the period with most
of the snow wrapping up before 18z except for RNH/EAU. There are
only a small number of current radar returns producing
drizzle/freezing drizzle with one having moved over the MPX
office at around 11z, and they are moving fast enough such that
accumulations are not expected. CIGS will fall into low MVFR/IFR
during the latter half of the period, with LIFR possible with
fog becoming the main issue later on. Right now, there is still
some uncertainty where the line of low stratus sets up later in
the period, with fog where there is a lack of low level cloud
cover reducing visibility and bringing the best chance for LIFR
CIGS. Winds remain below 5kts throughout, beginning 300-330 but
becoming calm and eventually 150-180 by end of period.

KMSP...Decided to omit a mention of -fzdz during the first 30
minutes of the period despite some drizzle at MPX, with a
trajectory taking that shower just south of the terminal. If it
does end up reaching MSP, it will only last 10 minutes or less
with no accumulation, with the best chance for legitimate light
snow being roughly 14-17z with minimal reductions to visibility
and minimal accumulation.

/OUTLOOK FOR KMSP/
WED...MVFR, chc IFR. Wind SE 5-10kts.
THU...MVFR/IFR. Wind S 5-10kts.
FRI...MVFR/IFR, chc -SHRA. Wind SE 5-10kts.

&&

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

&&

$$

DISCUSSION...PV
AVIATION...TDH