Harrisburg, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

440
FXUS63 KFSD 091132
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
632 AM CDT Sat May 9 2026

.KEY MESSAGES...

- Scattered very light showers or sprinkles possible today.

- Locally elevated fire weather concerns this afternoon with
  low relative humidity and marginally gusty winds.

- Patchy frost possible around highway 14 late tonight into
  Sunday morning.

- Temperatures begin to warm through the upcoming work week,
  and by the end of the week may be approaching the lower to
  middle 80s with outside chances of 90 by the weekend.

- Rain chances for the week ahead will be focused on Monday
  night and again Thursday, though amounts will stay low. Severe
  weather risks also remain low.

&&

.UPDATE...
Issued at 234 AM CDT Sat May 9 2026

One wave will move by to the northeast this morning while another
moves by to the southwest this afternoon and evening. Both waves are
moisture starved but have just enough moisture and weak instability
to allow for some very light showers or sprinkles. Impacts will be
minimal as will be rainfall amounts.

This afternoon will be another with locally elevated fire weather
concerns, albeit with lesser winds than yesterday. Still anticipate
a few gusts of 20 to 25 mph with afternoon humidity around 25
percent. For the most part fuels are very green, but warm season
grasses remain mostly cured.

A ridge of high pressure noses into the area late tonight into
Sunday morning and should support lows mostly in the 30s. Areas
closer to highway 14 may get cold enough to support some patchy
frost but confidence is too low to include a frost advisory for
now.

&&

.DISCUSSION...
Issued at 1248 PM CDT Fri May 8 2026

THIS AFTERNOON: A warm, dry, and windy afternoon continues
throughout the forecast area this afternoon. As temperatures
rise into the 70s, we`ll continue to see RH values fall towards
the 20% range. As we reach peak mixing, gusts should begin to
top in the 20 to 30 mph range in the Tri-State area. While RFW
criteria may be met for a couple hours this afternoon, recent
greenup should prevent widespread extreme fire behavior.
Soundings continue to show the very low probability of isolated
showers popping up after 21Z in areas along but mostly southeast
of I-90. Severe storms not expected, but brief 30-40 mph wind
gust may be possible.

TONIGHT:  Winds settle down this evening, but will remain southwest
through the night.  This results in warmer overnight low
temperatures in most locations.

SATURDAY: By daybreak Saturday, confidence remains high that a
weak cold front will settle southward through the area. By 12Z
this front may be just north of I-90 bringing with it a change
to a northerly surface wind, but also a low probability for high
based sprinkles/showers/virga. Once this front clears the area,
temperatures slowly warm back to the mid-60s, with breezy
northerly winds into the early evening.

SUNDAY: Temperatures remain cool on Sunday under the influence of
Canadian high pressure.  With a light north wind continuing, high
temperatures stay in the middle to upper 60s.

MONDAY-WEDNESDAY:  We`ll begin to see a gradual rise in temperatures
as mid-lvl heights rise through the Plains. Despite a breezy
southeast wind Monday afternoon that could lead to elevated fire
danger, high temperatures return to the 70s in most locations with
20-30% probabilities of 80+ degree temperatures in south central SD.
A frontal boundary swings eastward Monday evening and overnight.
MLCAPE profiles suggest some potential for 500-1000 J/KG through
central SODAK, but moisture itself remains very limited and there is
also a bit of capping in place. This should limit the overall
developmental potential of any activity that tries to develop as the
front moves east overnight. Temperatures cool slightly on Tuesday as
low-lvl flow shifts to the northwest. The latest NBM suggests
potential for 30 to 40 mph afternoon wind gusts, which is a signal
within the EC/CMC deterministic and ensemble guidance. The GFS/GEFS
is quite a bit lower, but if these winds do develop, then fire
danger may be quite elevated through the region. Overall
probabilities of exceeding 30 MPH are greater than 80%, with
potential of 40+ mph around 10-20%. Winds again turn to the south on
Wednesday, keeping high temperatures in the middle to upper 70s.

THURSDAY-SATURDAY: While quite a bit of uncertainty remains in the
specifics for the end of the week, overall trends in ensemble data
suggest a warming trend continues into next weekend.  Mid-lvl
heights continue to rise through the end of the week, pushing 850mb
temperatures into the 20C range by Friday.  The presence of several
weak mid-lvl perturbations adds some uncertainty to the forecast in
regards to thunderstorm and cloud potential. This is partially
why the NBM 25/75th percentile temperature spread climb to
nearly 10-15 degrees by Thursday and Friday. However, the broad
synoptic pattern does seem to favor more convection risks
(perhaps even stronger convection) within the region by next
weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 630 AM CDT Sat May 9 2026

VFR through the period. Spotty sprinkles and very light showers
will be possible through the morning, gradually weakening and
slipping southward. Otherwise north to northwest winds are
expected with gusts through the afternoon around 20 to 25 mph.

&&

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

&&

$$

UPDATE...08
DISCUSSION...Dux
AVIATION...08