258
FXUS63 KFSD 222251
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
451 PM CST Fri Nov 22 2024

.KEY MESSAGES...

- Some potential for fog development across portions of north
  central Iowa, southwestern Minnesota and areas along the
  Buffalo Ridge into South Dakota into Saturday morning. Locally
  dense shallow fog possible.

- Colder conditions remain on track for the holiday week.
  Confidence remains high (>80% chance) for high temperatures to
  largely remain at or below freezing. Wind chills are also
  likely (60-80% chance) to remain in the teens and 20s
  throughout the week, potentially colder on Friday.

- Light precipitation chances continue to trend downward for
  the middle of next week. Wednesday night has the highest
  potential for light snow, with only a 15-20% chance.

&&

.DISCUSSION...
Issued at 219 PM CST Fri Nov 22 2024

THIS AFTERNOON: Outside of cirrus, skies remain mostly clear
throughout the Tri-State area Friday afternoon.  Temperatures are
warming into the 30s in most locations.

TONIGHT: A weak mid-lvl shortwave moves through the Northern Plains
overnight, increasing both low-mid lvl warm advection, and resulting
in an increase in cloud cover through Saturday morning.   This low-
lvl warm advection, light surface mixing, and increased cloud cover
may keep temperatures warmer than previously forecast.  One
exception could be where light and variable winds develop along
higher elevation locations of southwest Minnesota and north central
Iowa.  Within this area, fog may begin to develop late this evening,
with mixed signals as far as the overall coverage and visibility
reductions.  The smattering of high resolution models both
indicating and not indicating fog lowers overall probability data
from the HREF/NBM to only around a 30% probability of dense fog.
Soundings would suggest any fog that develops may be quite shallow.

SATURDAY-SATURDAY NIGHT: Passing mid-lvl energy may bring very light
echos through central Minnesota early Saturday, with this activity
and associated mid-lvl clouds moving away from the area through the
day. Light southerly winds develop Saturday, as H850 temperatures
climb towards the +10C mark near the MO River valley by mid-day. The
end result will be an above  normal temperature day with highs in
the 40s.  Have boosted high temperatures towards the 75th percentile
of the NBM.  Overnight lows will stay above normal Saturday night
thanks to persistent light mixy southerly winds ahead of an
approaching frontal boundary.

EXTENDED FORECAST:

Sunday will end the weekend with near seasonable temperatures as 850
mb temperatures cool to either side of zero degrees C aloft. Mixing
this to the surface will result in high temperatures from the mid
30s to upper 40s, warmest across northwest Iowa. These warmer
temperatures are due to a surface trough sliding through the
forecast area throughout the day. While the main cold front will be
south of the area, the cold air advection behind the front will
usher in a colder airmass. This will lead to cooler low temperatures
as lows fall to the mid teens to mid 20s from northwest to
southeast.

The previously mentioned colder airmass looks to be here to stay for
the entirety of the holiday week. High temperatures look to only
warm to up to about freezing or less. Ensembles support this
possibility as they all show a near 100% chance for temperatures to
remain at or below freezing Monday through Friday. Depending on how
some shortwave troughs pass through the broader upper level flow,
locations south of I-90 could see warmer high temperatures just a
bit above freezing on Tuesday and Wednesday. Low temperatures will
also be cool, with lows bottoming out in the single digits and
teens. Winds do not appear to be that strong throughout the holiday
week, but a few days could see breezy northwest winds. The colder
conditions along with the breezy winds will make for colder wind
chills across the area. Wind chill values down to the teens and 20s
is likely (60-80% chance). In fact, the ensembles also hint at the
possibility of single digit to below zero wind chills on Friday with
a 50-80% chance for wind chills below 10 degrees F.

In terms of precipitation, chances for light snow have continued to
trend downwards. As of now, the best chance (15-20%) for seeing any
light snow would be Wednesday night. Ensembles continue to support
this as they show a 40% chance or less for a hundredth of an inch of
precipitation or more. All this to say that the holiday week will be
generally dry and cold.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 450 PM CST Fri Nov 22 2024

Winds will become light and variable overnight, and there will
be a low probability for fog development through portions of
east central SD, southwestern MN, and northwest IA into Saturday
morning. Winds will increase a bit out of the east/southeast by
later on Saturday morning. Otherwise, mid and high clouds will
stream across the region through the period.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...Dux/Meyers
AVIATION...JM