344
FXUS63 KFSD 140723
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
123 AM CST Tue Jan 14 2025

.KEY MESSAGES...

- Light snow will continue through the early overnight hours as
  the band of snow sags south. Amounts are expected to mainly be
  a half an inch or less for most locations, with very isolated
  amounts near an inch. The highest snowfall totals will be
  south of I-90.

- Cold wind chills are expected tonight with wind chill values
  down to -5 to -20F. The coldest wind chills will reside
  across southwest Minnesota.

- Roller coaster temperatures are expected throughout the week.
  Below normal temperatures continue through Tuesday, warming
  mid week, then plummeting on Friday through the weekend.

&&

.UPDATE...
Issued at 120 AM CST Tue Jan 14 2025

Temperatures this morning have been falling more quickly than
previous forecast as cloud cover sags south and surface high
pressure moves in. Even with weakening winds, we are reaching
wind chill values of -25 degrees or colder. Have issued a Cold
Weather Advisory for the Buffalo Ridge and adjacent counties
until 9 AM CST. Will continue to monitor trends for potential
expansion. Elsewhere, wind chills are in the teens below so
bundle up regardless of headlines.

&&

.DISCUSSION...
Issued at 247 PM CST Mon Jan 13 2025

Cloud cover continues to overspread the area this afternoon as the
next chance for light snow is just beginning to work its way into
locations across central South Dakota. This light snow is expected
to push south/southeastwards and expand in coverage. The expansion
in coverage will result in a band of snow that is being forced from
frontogenesis (FGEN) between 925-850mb. This could be a tighter band
of snow as latest hi-res guidance shows a hint of negative
equivalent potential vorticity (EPV) above the FGEN surface. This
could also slightly increase snowfall amounts. However, think that
amounts generally remain on track with most locations seeing below a
half an inch with a few isolated spots seeing up to around an inch,
highest across south central South Dakota.

The other aspect to tonight is cold wind chills across the area.
Wind chills are expected to fall to -5F to about -20F overnight
tonight, coldest across southwest Minnesota. A few locations across
southwest Minnesota could see wind chills fall near -25F (Cold
Weather Advisory criteria). However, have held off on issuing an
Advisory at this time as there remains some uncertainty in how long
clouds cover will last overnight. On top of this, HREF probabilities
for apparent Temperature`s falling below -25F remains at a 30-40%
chance. Short term trends will be monitored for the rest of today
though. That said, make sure to bundle up as you head out the door
for work tomorrow!

Tuesday will be a cold but quiet day as the previously mentioned
surface high pressure system sinks southward. 850 mb temperatures
down to around -10C will result in another day of below average high
temperatures with highs only warming to about 10F-20F. Although
winds will be light and variable, the light winds will keep cold
wind chills going through the day with wind chills down to either
side of 0F. Low temperatures will only fall to the positive single
digits overnight, keeping wind chills confined to about 0 to -10F.
While not near headline criteria, it will still be another cold
night.

Temperatures begin to warm on Wednesday as weak upper level ridging
builds into the Northern Plains. Mid level warm air advection (WAA)
will push 925 mb temperatures up to either side of 0C aloft. Mixing
these temperatures to the surface will result in above average high
temperatures up to the upper 20s and 30s. The Northern Plains will
reside on the edge of the upper ridge on Thursday. This will warm
925mb temperatures a touch more, up to the single digits above 0C.
This will result in high temperatures warming to the mid to upper
30s and low 40s. The warmest temperatures will reside along the
Missouri River. Low temperatures both days will fall to the 20s
overnight.

The warm temperatures will not last long though as a strong cold
front will push through the Northern Plains on Friday. This will
bring a new arctic airmass to the region. While high temperatures on
Friday may still reach the 30s to potentially up to about 40F,
temperatures will quickly plummet to the single digits and teens
overnight. With a new airmass in place, below average temperatures
will continue as high temperatures only warm to the teens to low 20s
on Saturday and single digits on Sunday. Low temperatures will fall
to the negative single digits Saturday night and negative single
digits to negative teens Sunday night. Breezy winds look to
accompany the cold temperatures which could result in future Cold
Weather Advisories being needed. Too far out to say for sure at this
time but trends will be monitored.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1021 PM CST Mon Jan 13 2025

A band of snow producing about a half an inch to an inch of snow
will sag south through northwest IA and southern SD by 6-8z. A
period of MVFR and possibly IFR conditions are expected as the
band settles south. Cold air will clear out the clouds and snow
quickly from the north and VFR conditions expected everywhere
after about 9z.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Cold Weather Advisory until 9 AM CST this morning for SDZ040.
MN...Cold Weather Advisory until 9 AM CST this morning for MNZ071-
     072-080-081-089-090-097.
IA...None.
NE...None.

&&

$$

UPDATE...SG
DISCUSSION...Meyers
AVIATION...08