671
FXUS63 KFSD 121148
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
648 AM CDT Thu Mar 12 2026

.KEY MESSAGES...

- Strong winds are expected late Thursday afternoon into
  Thursday night with gusts 55 to 75 mph expected, the highest
  gusts most likely north of I-90. A High Wind Warning is now in
  effect for the entire area late Thursday afternoon into
  Thursday night.

- A Red Flag Warning is in effect for Thursday afternoon and
  early evening. Windy and dry with generally fully cured fuels
  and dry conditions.

- The potential for major travel impacts due to snow and wind
  will arrive Saturday and continue into Sunday. Stay tuned for
  updates and be prepared for possible changes to plans on those
  days, especially Saturday night into Sunday.

&&

.UPDATE...
Issued at 440 AM CDT Thu Mar 12 2026

Early morning area of fog continues over the lingering snow cover
in parts of northwest Iowa, where light winds/clear skies and fresh
snow optimized radiational cooling. Looking at obs and webcams, does
not appear that dense fog is widespread, but did issue a Special
Weather Statement to highlight changing visibility for travelers as
we head into morning commute times. Fog will likely persist through
sunrise but should improve pretty quickly as mixing and winds begin
to increase.

High winds by late afternoon through tonight remain the primary near
term concern and no significant changes there. However, made a few
adjustments to pops/QPF through this evening in deference to latest
CAMs. Decent consensus that activity through midday-early afternoon
will be pretty spotty given dry sub-cloud layer, though be aware
that virga or sprinkles could further enhance the pre-frontal winds.
Broader shower development becomes more likely by late afternoon and
evening along/behind the cold front, mainly north through east of
Sioux Falls, as the cold advection creates some weak instability and
lowers cloud bases to 5kft AGL or lower. Fortunately, temperatures
and dew points will be near to above freezing during this activity,
so this precipitation should remain liquid.

Issued at 957 PM CDT Wed Mar 11 2026

Model soundings continue to indicate strong west southwest winds on
Thursday which will lead to critical to near critical fire danger for
many locations. Some indications that the stronger winds could start
to mix down by mid to late morning with a strong core of winds not
too far off the surface. The locations most at risk will be near and
south of a Huron to Spencer IA line. Afternoon RH levels drop to 25
to 35 percent with expected wind gusts approaching 40 mph at times,
likely averaging about 25-35 mph. The only question mark may be some
extensive cloud cover which could limit heating a bit, but strong
mixing as low pressure deepens to the north should allow for deeper
mixing.

As this low pressure deepens and drops southeast into MN, strong CAA
will move through the area with wind gusts of 50 to 75 mph likely.
Confidence continues to grow that gusts will not only reach 60 mph,
but could approach or exceed 75 mph given very high winds near the
top of the mixed layer in the RAP and HRRR. Have expanded the high
wind warning across the entire area for Thursday night.

Attention then turns to the weekend, particularly Saturday night
into Sunday. Most of the major models are suggesting strong winds
and a band of heavy snow within the four state region with the EC
Ens, Canadian Ens and GEFS indicating a 40-70% chance for a half an
inch of liquid with a 10-20% chance for an inch or more of liquid
content. That would likely equate to a band of 5-10 inches of snow.
Some potential that the southern side of the band could be fairly
tight, so any movement north or south could equate to some large
local differences. The main message here is that if traveling, there
is a good chance hazardous to potentially dangerous conditions are
expected. Currently looks like the heaviest snow would be Saturday
night into Sunday morning with very strong winds, possibly at or
above 50 mph, on Sunday.

&&

.DISCUSSION...
Issued at 310 PM CDT Wed Mar 11 2026

CURRENTS & TONIGHT: Another cool day continues! Taking a look across
the area, mostly clear conditions persist this afternoon as
temperatures approach the mid 30s to low 40s across the area. While
this has succeeded in melting most of the snow, still have a light
snow pack across portions of far southeastern SD and northwestern
IA. With this in mind, have slightly decreased temperatures for the
day with most areas topping out in the upper 30s to upper 40s with
the mildest conditions across southcentral SD. Shifting gears to
precipitation, we`re starting to see a few sprinkles to light
showers develop mostly along the Highway-14 corridor mainly in
response to the arrival of a shortwave. However, much of this won`t
reach the ground due to a dry sub-cloud layer according to
soundings. Lastly, another cool night is ahead with lows mainly in
the low to mid 20s.

THURSDAY: Looking into Thursday, things will get pretty interesting
aloft as a decently strong clipper wave crosses into the Northern
Plains and Great Lakes regions bringing strong winds, light rain,
and lower humidity values at times. Starting with the precipitation,
a strong surface warm front will progress through the area on the
nose of jet streak. This combined with a little bit of isentropic
lift should lead to scattered showers developing across areas mainly
north of I-90 between the afternoon and evening. While accumulations
of 0.10" of an inch or less are expected, can`t completely rule out
a few hundredths across northwestern IA as well. Next, a well-mixed
environment along with increasing mid-level warm air advection (WAA)
will lead to temperatures in the 50s to mid 60s for the day with the
warmest conditions across the Missouri River Valley. This combined
with lower RH values will likely lead to some elevated fire weather
concerns on by Thursday afternoon (more details in the fire weather
section).

Finally, we`ll shift over to the main concern which are the stronger
winds. A tightening SPG along with an approaching cold front will
lead to increasing southwesterly to westerly winds between Thursday
afternoon and Friday morning. Given the mixy environment and strong
LLJ (85-95 mph at 700 mb), wind gusts between 45-55 mph with pockets
of 60+ mph are expected across most of the area. With this in mind,
decided to upgrade part of our High Wind Watch to a High Wind
Warning mainly north of a Tyndall to Canton to Spirit Lake, IA line.
Anything south of the line was kept in a High Wind Watch. The
current thinking was to upgrade the parts of the watch that we have
the highest confidence of higher wind speeds. While we can`t rule
out additional upgrades to the watch, decided this would be a good
starting point to emphasis the stronger winds.

FRIDAY ONWARDS: Heading into the extended period, an active pattern
will continue aloft through at least Saturday. Persistent northwest
flow will help usher in multiple system into the weekend potentially
leading to accumulating snowfall on both Friday and Saturday. While
some of the 11.12z guidance has started to come into better
agreement with features, there is still some uncertainty as far as
amounts. Nonetheless, with the potential for moderate to heavy
and/or mixed precipitation make sure to monitor your local forecast
heading into St Patrick Day weekend and be prepared to alter any
travel plans. Otherwise, we`ll get another taste of winter
temperature-wise over the weekend with highs decreasing into the 20s
to low 30s on Sunday and Monday.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 625 AM CDT Thu Mar 12 2026

Strong to damaging winds are the primary concern this morning,
especially during the latter half of the TAF period.

South-southwest winds increase this morning with gusts 25-35kt
developing after 12/15Z. Late afternoon virga/sprinkles could locally
enhance gusts to 40-50kt with erratic direction. However, more
widespread damaging wind gusts in excess of 50kt expand across the
region after 13/00Z and continue through the early hours of Friday
morning.


&&

.FIRE WEATHER...
Issued at 1122 PM CDT Wed Mar 11 2026

Southerly flow will quickly increase Thursday mid-morning and turn a
bit more west southwest through the afternoon. Wind gusts of 25 to
40 mph are expected through the afternoon. Along with the strong
winds will be dry conditions with the relative humidity falling
to 25 to 35 percent generally near and south of a Huron to
Spencer IA line. A Red Flag Warning is in effect near and south
of this line.

Near and north of this line the relative humidity will remain
higher along with what looks to be a bit more extensive cloud
cover. There will also be the potential for a few rain showers
in this area.

While the relative humidity will improve Thursday evening, a
very strong cold front will bring northwest winds with gusts of
55 to 75 mph likely. Burning is highly discouraged Thursday.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning from noon today to 9 PM CDT this evening for
     SDZ038-050-052>055-057>071.
     High Wind Warning from 9 PM this evening to 7 AM CDT Friday
     for SDZ066>071.
     High Wind Warning from 7 PM this evening to 7 AM CDT Friday
     for SDZ038>040-050-052>065.
MN...High Wind Warning from 7 PM this evening to 7 AM CDT Friday
     for MNZ071-072-080-081-089-090-097-098.
IA...Red Flag Warning from noon today to 9 PM CDT this evening for
     IAZ001>003-012>014-020>022-031-032.
     High Wind Warning from 9 PM this evening to 7 AM CDT Friday
     for IAZ001>003-012>014-020>022-031-032.
NE...Red Flag Warning from noon today to 9 PM CDT this evening for
     NEZ013-014.
     High Wind Warning from 9 PM this evening to 7 AM CDT Friday
     for NEZ013-014.

&&

$$

UPDATE...JH/08
DISCUSSION...05
AVIATION...JH
FIRE WEATHER...08