300
FXUS63 KFSD 241745
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1245 PM CDT Fri Apr 24 2026

.KEY MESSAGES...

- Showers and very isolated thunderstorms expected tonight into
  Saturday (80-90 percent chance near and north of I-90).

- Scattered to numerous (80-100%) showers and storms expected
  again Sunday into Monday. Areas of heavier rainfall are
  possible but for now flooding and flash flooding chances
  remain low (less than 20 percent).

- A very small chance the severe weather could creep north
  towards northwest IA and the Mo River Valley Sunday night, but
  confidence is very low.

- Seasonable temperatures expected through mid next week, with
  highs mostly in the mid 50s to mid 60s.

&&

.DISCUSSION...
Issued at 1243 PM CDT Fri Apr 24 2026

Upper level low pressure well to the north of the area will swing a
smaller piece of energy into the area tonight into Saturday. Fairly
strong mid level frontal forcing develops in response to this wave,
with some of the stronger forcing in the 700-750mb layer. Late
tonight into Saturday morning the front closer to 800-850 mb looks
to be more active and could shift some of the better precipitation
closer to I-90. Overall amounts within this band of rainfall will
likely be about a quarter to three quarters of an inch. Instability
is minimal so other than a few rogue lightning strikes this will
mainly be a welcome rain event.

Weak upper level support and low to mid level warm advection
continues through most of Saturday and given some very weak
instability in the soundings, scattered showers will remain likely
through the day. Some isolated thunderstorms will also be possible,
but severe weather is not expected tonight through Saturday. The
better chances for rain should remain mostly north of I-90 but could
be a little more spread out across the area with isolated to
scattered activity and more disorganized forcing.

Weak upper level ridging builds ahead of a stronger wave Saturday
night into Sunday morning. This could be a period where activity is
the most isolated.

Upper level support rapidly increases Sunday afternoon into Sunday
night, leading to the areas best chance for some heavier rain Sunday
night into Monday. Marginally steep elevated lapse rates along with
strong low level moisture convergence will lead to showers and
thunderstorms for much of the area. The trends to watch for on Sunday
night will be the potential for the better forcing to produce
heavier rainfall west of I-29 towards central into northeast SD and
another area closer to northwest IA and points south where deeper
instability could produce an MCS with that activity shifting more
eastward. A very small threat for severe weather in northeast NE and
northwest IA Sunday night, although model soundings and Ensemble
output indicate only a very small chance for CAPE values above 1000
J/kg.

Low pressure aloft deepens over southeast SD Sunday night and slowly
drifts east through Monday. This will continue the threat for rain
into Monday afternoon, likely ending Monday evening most locations.

Rainfall amounts continue to trend higher with the latest NAM
producing a fairly large area of 2-4" of rain for most of southeast
SD through tonight through Monday. The latest GFS is very similar,
just a touch lower on amounts with the Canadian and RRFS a little
farther north and west with the heavy rain amounts. The latest 50th
percentile from the GEFS gives the area 1-2" with the higher amounts
north of I-90. The Canadian ensemble parks the higher 2" amounts
across most of southeast SD. The 6z EC Ensemble very similar to this
output as well.

Once this system finally exits, mainly north to northwest flow aloft
is expected Tuesday into Friday which will keep seasonally cool
temperatures close to normal in place each day. While there will be
a few chances for showers and maybe an isolated thunderstorm the
activity looks to remain fairly isolated and fairly light.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1243 PM CDT Fri Apr 24 2026

VFR through the period east of I-29. West of I-29 a band of rain
will move into central SD early this evening then shift east and
a bit south through the night into Saturday morning. The better
chances for MVFR and pockets of IFR ceilings will be later
tonight into Saturday along and north of I-90 and mainly west of
I-29. A very isolated thunderstorm will be possible but overall
this should mainly be a rain threat.

&&

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

&&

$$

DISCUSSION...08
AVIATION...08