Expires:No;;272545
FXUS63 KFSD 262005
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
205 PM CST Fri Dec 26 2025

.KEY MESSAGES...

- Fog is likely to redevelop tonight, with the better chances 
  near and east of I-29. Some dense fog will remain possible.

- Much above normal temperatures on Saturday will turn sharply 
  colder Sunday accompanied by northwest winds gusting 30 to 50 
  MPH. Sub-zero wind chills are expected Sunday night through 
  early Monday.

- Light snow is likely on Sunday. The latest model runs are a 
  bit more aggressive on producing around an inch of 
  accumulation, especially south and east of a Tyndall to 
  Jackson MN line. Some strong winds could cause some blowing 
  snow, but most areas are completely snow free now which will 
  help keep the blowing to a minimum.

&&

.DISCUSSION...
Issued at 205 PM CST Fri Dec 26 2025

Fog remains the main challenge through tonight into Saturday. A 
quick ridge of high pressure at the surface will move through, with 
winds turning south and southeast this afternoon into tonight. 
Visibilities will improve through the afternoon, but areas 
especially near and east of I-29 will likely see dense fog redevelop 
shortly after sunset and continue into the morning. Confidence is 
not quite as high as this morning as the moisture is becoming more 
shallow. 

Southerly flow increases on Saturday and becomes a bit more 
southwesterly which should aid in dissipating the low level inversion 
and thus the moisture trapped below it. This southwest flow should 
bring the area the warmest day with highs from the upper 40s to 
around 60, warmest in south central SD.

Saturday night into Sunday will see a wave move through the area 
bringing the next chance for precipitation. While some brief mixed 
precipitation will be possible with a somewhat dry warm layer aloft, 
once the better precipitation develops all snow is anticipated. 
While snowfall amounts by themselves will only produce minor 
impacts, northerly winds gusting around 45 mph could produce some 
blowing snow. However, as opposed to our previous blowing snow event 
about a week ago with some very low visibilities, these winds will be 
about 15-20 mph lower and for the most part all areas are snow free. 
This should limit how much snow will blow and will of course be 
completely limited to what falls. The latest GEFS gives a pretty 
good chance for 1-2" of snow while the EC AI and EC Ensemble stick 
to an inch or less. Both suggest the better chances will be for areas 
in and around northwest IA. For now the Nam is an outlier by 
producing the better chance for 1-2" of snow mainly north of I-90. 
Will need to monitor trends of the small vort max that drops south 
behind this wave late Sunday afternoon into Sunday night. This could 
produce some snow showers with some fairly strong winds, but 
confidence a little low on whether or not we get snow with this 
feature.

The other side of this wave will be the wind and cold. Very strong 
cold air advection develops late Saturday night into Sunday morning. 
A sold core of strong low level winds and pressure rises support 
frequent wind gusts of 40 to 50 mph, which should continue into 
Sunday night, tapering off from northwest to southeast. These winds, 
when combined with the incoming cold air, will produce wind chills of 
-10 to -20 Sunday into Monday morning.

Northwest flow remains fairly strong overhead Tuesday into Friday. A 
brief warm on Tuesday will be followed by a moderately cold shot of 
air, bringing temperatures back below normal. A quick shot of warm 
advection ahead of this shot of colder air Tuesday night into 
Wednesday could bring another round of light snow.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1131 AM CST Fri Dec 26 2025

IFR and LIFR conditions will continue, especially near and east
of I-29 and particularly in northwest IA. While improvements 
are expected through the afternoon, IFR and LIFR conditions that
do dissipate will likely return tonight as light south and 
southeast winds help advect back the low level moisture in Iowa.
The near surface moisture is a bit more shallow than the 
previous couple of days, so confidence a bit lower, but still 
moderate to high for LIFR conditions.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...Dense Fog Advisory until 9 AM CST Saturday for MNZ089-090-098.
IA...Dense Fog Advisory until 9 AM CST Saturday for IAZ001>003-
     012>014-020>022-032.
NE...None.

&&

$$

DISCUSSION...08
AVIATION...08