745
FXUS63 KABR 201816
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1216 PM CST Mon Jan 20 2025

.KEY MESSAGES...

- Arctic air with dangerously cold wind chills will remain in
  place into Tuesday morning, ranging from -25 to near -50. The
  lowest values will be over northeastern SD and west central MN.

- Warmer air returns the middle of the week with temperatures
returning closer to normal if not slight above normal.

- There a 20 to 30 percent chance of snow will be possible Wednesday
into Wednesday night with only minor accumulations anticipated.

&&

.UPDATE...
Issued at 1216 PM CST Mon Jan 20 2025

The ongoing -40 or below wind chills will persist longer over the
Prairie Coteau of northeastern SD. As a result, the Extreme Cold
warning has been continued through tomorrow morning there. The
Extreme Cold Warning was already in place for our far northeastern
SD and west central MN counties. Slowly diminishing winds and a
slight increase in temperatures early this afternoon will result
in improving wind chills elsewhere. Still, they will be low enough
to keep Cold Weather Advisories in place through Tuesday morning.

Other changes have been to highlight the ongoing lake
enhanced/river enhanced light snow and reduced visibilities off
the Missouri River. We`ll continue to monitor the flurries over
northeastern SD and west central MN that brought a light dusting
of snow early this morning to a few locations. The next concern is
a slight increase in chances of snow Tuesday afternoon into
Tuesday night.


&&

.SHORT TERM /TODAY THROUGH TUESDAY AFTERNOON/...
Issued at 315 AM CST Mon Jan 20 2025

The coldest push of arctic air is arriving now, with the coldest
temps upstream in ND and north central SD. Eureka is checking in
with a 40 below wind chill as of 230 am. As the colder air arrives
the wind chills will really bottom out most locations by daybreak.
Some low clouds are forming in the colder air and will stick around
most of the day. Streamers off lake Oahe continue to affect the
Pierre area as well.

The current headlines in place look really good. Will add in the SE
counties to match up better with FSD and the latest guidance
suggests extreme cold warning criteria this am, but overall it looks
good with the coldest apparent temps this morning with slight
moderation during the day.

By this afternoon 1045 mb sfc high pressure settles into the state
and will shift southward tonight. This will allow the wind to turn
to southwest and begin the moderation process for more moderate
temps into Tuesday. Temps could be as much as 30 deg or more warmer
by Tuesday afternoon, especially west river.

&&

.LONG TERM /TUESDAY EVENING THROUGH SUNDAY/...
Issued at 315 AM CST Mon Jan 20 2025

Tuesday evening an upper-level shortwave is moving southeast towards
SD, and moves over the state Wednesday morning. However, there are
some slight differences in the models of the location that also
translates down to the attached surface low and its precipitation.
Some models have precipitation developing over central SD Tuesday
evening while others wait until Wednesday morning to develop
precipitation. The differences in the position of the surface low,
as well as pockets of mid-level dry air, in the models contributes
to differences in the timing and location of the precipitation. The
models have had an increasing trend with an area of precipitation
occurring west of the James River Valley overnight into Wednesday
morning, with thinner bands of precipitation occurring Wednesday
into Thursday over central and eastern SD. Though there is still
some uncertainty with the location of the precipitation as
disagreements in the models has kept forecast confidence lower. One
thing for certain is the type of precipitation that will fall. Mid-
level CAA Wednesday into Thursday will keep the hydrometers frozen
as they fall causing the precipitation to fall to the surface as
snow. QPF values have also increased slightly, especially in the
larger swath of snow west of the James River Valley, with the
clusters showing a 30-60 percent chance for a half inch of snowfall
over areas in central SD. The thinner bands have lighter
precipitation and smaller QPF values, leading to a 40-70 percent
chance of 0.1in of 24hr snowfall from Wednesday evening to Thursday
evening over central and eastern SD.

Surface winds Wednesday are another slight area of concern. Tuesday
evening into Wednesday, there are strong 0.5km winds with
semi-decent lapse rates to get some of these winds aloft to the
surface. Surface winds look to increase overnight Tuesday into
Wednesday morning around and west of the Missouri river, with some
area reaching 25 to 35 mph winds. These winds will increase speed
and spread east into the James River Valley by the afternoon before
decreasing in the evening. Areas where these winds and the snowfall
could overlap will potentially see scattered areas of blowing snow,
which could decrease visibilities and cause some hazards for those
traveling.

The models and clusters are consistent with an upper-level ridge
moving towards the southeast over SD Friday, though there is some
variation in the location and timing. This then leads to some
uncertainties in the chance of precipitation falling over central
and eastern SD during the day Friday. At the moment, most of models
have the precipitation over ND, with some reaching into SD over the
Prairie Coteau, though the clusters have a 30-50 percent chance for
0.1in of snowfall occurring. Temperatures Friday onward look to be
around normal for this time of the year.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1216 PM CST Mon Jan 20 2025

Terminals KABR,KATY,KPIR,KMBG

VFR to MVFR conditions continue with cold air cumulus clouds not
only moving across in the northwesterly flow, but additional
streamers of lake enhance/river enhanced clouds and snow showers
off the Missouri River that are moving over MBG and PIR at times.
The lowest reductions in visibility will remain at PIR, at around
3SM or greater this afternoon.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Extreme Cold Warning until noon CST Tuesday for SDZ007-008-011-
     020>023.

     Cold Weather Advisory until noon CST /11 AM MST/ Tuesday for
     SDZ003>006-009-010-015>019-033>037-045-048-051.

MN...Extreme Cold Warning until noon CST Tuesday for MNZ039-046.

&&

$$

UPDATE...KF
SHORT TERM...Scarlett
LONG TERM...Vernon
AVIATION...KF