Sioux Falls, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

155
FXUS63 KFSD 212301
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
601 PM CDT Wed May 21 2025

.KEY MESSAGES...

- Quiet, but cool weather continues through Thursday.
  Occasional sprinkles to drizzle may be possible at times into
  Thursday. Rainfall amounts minimal.

- Rain chances return on Friday and persist occasionally
  through the Memorial Day holiday. Rainfall though will light
  over the 4 day weekend, with probabilities of >0.50" between
  30 and 60%.

- Temperatures also remain cool through the holiday, with the
  first chance for 70 degree highs not arriving until Tuesday.

&&

.DISCUSSION...
Issued at 145 PM CDT Wed May 21 2025

THIS AFTERNOON:  Considerable strato-CU continues to rotate through
the region this afternoon as an upper low spins near the SD/ND
border.  Temperatures remain quite chilly despite a few localized
breaks in the sun, with highs only rising into the lower to middle
50s.

TONIGHT:  Clouds may thin slowly this evening after the loss of
sunlight, but with most of the area remaining under the influence of
the upper low to the north, this is expected to be a short break.
Temperatures may quickly fall towards the upper 30s.   The weakening
upper low drift southeast along the Buffalo Ridge, dragging a low
probability of sprinkles to drizzle southeast through the Tri-State
area into Thursday morning.   850MB temperatures are quite low AOA
-4C, sitting near the 10th percentile of climatology centered
 around mid-late May. This could suggest a flurry or two, but
 feel the depth of the boundary layer warm layer should prohibit
 any snowflakes reaching the ground. Given potential for clouds
 to hang on into the overnight, this likely limits frost
 potential.

THURSDAY: The upper low moves away on Thursday, producing dry
weather throughout the region.  Again, some self-destructing
sunshine will likely lead to more afternoon clouds. Temperatures
though will be a touch warmer towards the lower 60s.

FRIDAY:  Mid-lvl heights rise slightly through the Plains early
Friday morning in response to an upper wave crossing the Northern
Rockies.  However, models remain in strong agreement that isentropic
lift tied to this wave deepens Friday morning from western North
Dakota into central Nebraska. This will push a slow eastward moving
area of showers and isolated thunderstorms eastward through the
day. With the wave pulling slightly northeast in the afternoon,
some uncertainty remains on how far east any light rain may
fall. Very weak isentropic lift remains in place into Saturday
morning, keeping a risk for very light rain. QPF amounts though
will be less than 0.25" in most areas, with some focus along and
west of the James River.

SATURDAY-TUESDAY:   A bit of a mixed bag expected for the Memorial
Day holiday weekend, thanks to a deepening upper trough expected to
cross the Rockies through the weekend.  We`ll start the holiday
weekend with considerable cloudiness thanks to persistent easterly
surface and low level flow. Occasional very light rain may be
possible at times, though with the lack of any strong forcing, QPF
amounts will remain very light.  Temperatures remain below normal in
the upper 50s to lower 60s.

A bit more uncertainty builds on Sunday as a mid-lvl battle between
an upper trough over the Great Lakes and upper trough over Rockies
develops. Ascent will be increasing throughout the Western Plains
tied mostly to mid-lvl warm advection and dPVA. Further east
however, the trough moving through the Great Lakes may instead push
drier and more stable air southeast towards the Tri-State area.  In
the end, the uncertainty develops on just how far to the east
precipitation tracks on Sunday. This is also why most
probabilistic data suggests that the greatest potential for
more than 0.50" of rain is found mostly along and southeast of
the Missouri River.

The Memorial Day forecast remains highly uncertain given medium
range model struggles on resolving these two aforementioned troughs.
 The GFS suggests the Rockies trough remains the dominant feature
bringing widespread rain on Memorial Day, while the ECMWF suggests
the Great Lakes trough deepens and brings only slight risks for
rain. Given the extensive spread through the ensembles at even
low QPF totals, the PoP will remain in the 20 to 40% levels.
Temperatures through will continue to be cool for Memorial Day,
only in the low to mid 60s.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 557 PM CDT Wed May 21 2025

MVFR to VFR ceilings in place across the region currently will
hold into the overnight hours with some better cohesiveness to
the MVFR deck toward daybreak tomorrow morning. Trends will be
for ceilings to lift and begin to scatter out into the afternoon
hours Thursday with VFR conditions prevailing region-wide.

A few brief and light showers will also continue to pivot around
the upper level low this evening and overnight but any aviation
impact should be fairly minimal and brief and largely limited to
KHON and KFSD (if at all).

Winds will also keep a predominant northwesterly direction
through the period.

&&

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

&&

$$

DISCUSSION...Dux
AVIATION...Kalin