786
FXUS63 KFSD 051123
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
623 AM CDT Tue May 5 2026

.KEY MESSAGES...

- Tonight into early Wednesday will bring the greatest risk of
  near to below freezing temperatures this week, especially for
  portions of southeast South Dakota and southwest Minnesota.
  Take precautions to avoid damage to sensitive outdoor plants.

- Areas of frost or near-freezing temperatures will again be
  possible early Thursday morning, but near to above normal
  temperatures return Thursday afternoon through the weekend
  with highs mainly in the 60s to 70s.

&&

.UPDATE...
Issued at 410 AM CDT Tue May 5 2026

A few observations have dipped to freezing or below early this
morning, but these areas have begun to level off or even rebound
slightly as we begin to see some increase in mid to high level
clouds from the west. This will lead into a couple of chilly
early May days. While highs today and Wednesday will be in the
50s most areas, breezy northwest winds during the daylight hours
will make it feel even cooler.

Winds drop off tonight, setting the stage for what will likely
be the coldest night of the week. While NBM maintains lows in
the upper 20s to lower 30s over most of the CWA for Wednesday
morning, these values are 2-4 degrees colder than the mean low
temperature in raw model data with no bias-correction included.
Looking at it another way, the probability of daybreak temps
below 32F is 80+% over the northwest half of the forecast area
in the NBM, but less than 40% in the LREF raw ensemble data.
This lends some uncertainty to the low temperature forecast for
tonight, so opted to hold off another cycle on freeze headlines.
Day shift will take another look, though headlines will likely
be needed later today for at least part of the CWA.

&&

.DISCUSSION...
Issued at 126 PM CDT Mon May 4 2026

CURRENTS & TONIGHT: Another mild and breezy day persists! Taking a
look across the area, the breeziness continues behind this morning`s
cold front with most observations showing northerly wind with gusts
between 25-35 mph along with temperatures mainly in the 50s to 60s.
With deeper mixing and lower dew points, near-critical RH values
continue with values in the 25-30 percent range. While the
combination of the ingredients above have led to locally elevated
fire concerns; decided to hold off on any fire-related headlines
mainly due to greening fuels. Otherwise, can`t completely rule out a
few scattered sprinkles along and south of the Highway-20 corridor
this evening. Nonetheless, with limited saturation according to
sounding; expect any accumulations to very light at best. Lastly, as
cloud cover thins and surface winds lighten overnight; an influx of
cooler air will lead to temperatures mainly in the low to upper 30s
for the night. With this in mind, could see some patchy frost
develop mainly along the Highway-14 corridor overnight. While the
extent is still in question mainly due to a higher dew point
depression, decided to also hold off on an frost/freeze headlines at
this time.

TUESDAY-THURSDAY: Looking into the midweek, we`ll continue to sit in
northerly flow aloft as a predominantly troughy pattern continues
aloft. With lingering mid-level cold air advection (CAA) and
predominantly northwesterly flow in place at the surface, expect
temperatures to temporarily decrease through at least Wednesday with
highs mainly in the low to upper 50s. With lows expected to be near
to below freezing (26-32 degrees) each night, additional chances for
more widespread frost/freeze development are expected especially by
Wednesday. However, with an 8-10 degree dew point depression and
variable cloud cover at times; there are still some questions as to
extent of the frost/freeze. Nonetheless, we should be about to hit a
turning point by Thursday as increasing mid-level warm air advection
(WAA) and the return of southwesterly to westerly winds help highs
climb back into the 60s. Lastly, any precipitation chances continue
to look rather limited for the period.

THE WEEKEND: Heading into the extended period, an active pattern
will once again return as northwesterly flow helps usher in multiple
waves through our area. The strongest of which looks to arrive
between Saturday to Sunday. While there is still some variability
among long-range guidance, this still looks like our best chances
(30%-40%) for areas along and south of I-90 to see rain. This is
further agreed upon within ensemble guidance with most members
showing a 20%-40% chance of 0.10" of an inch or greater of QPF.
While not a drought buster by any means, any potential rain chances
are encouraged at this point. Lastly, we`ll continue our warming
trend into the weekend with highs mainly in the 60s to low 70s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 623 AM CDT Tue May 5 2026

Light west to northwest winds to start the period will become
more predominantly northwest as low level mixing develops mid
to late morning, with gusts 20-25kt midday through sunset. Mid
level cumulus 6-8kft AGL develops after 15Z-16Z and largely
dissipates again after sunset.


&&

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

&&

$$

UPDATE...JH
DISCUSSION...05
AVIATION...JH