579
FXUS63 KMPX 231755
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1155 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 /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1133 AM CST Mon Dec 23 2024

Some light drizzle/mist has been ongoing this morning with lower
cigs moving in from the north. This trend is expected to
continue with mainly MVFR/IFR conditions through early evening
before IFR/LIFR takes over. North-northwesterly winds will go
calm overnight, which will only help the fog chances. Very
little if any improvement in cigs are expected by the end of the
period. Winds will become southerly but remain under 5kts.

KMSP...After a few snow showers earlier in the day, the
remainder of the period should be dry aside from some mist/fog.
IFR cigs/vis settle in after 06z and are expected to improve
back to low end MVFR by late tomorrow morning/early afternoon.

/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...Dye