Harrisburg South Dakota Weather Forecast Discussion

945
FXUS63 KFSD 111736
AFDFSD
Area Forecast Discussion
National Weather Service Sioux Falls SD
1236 PM CDT Sat Oct 11 2025
.KEY MESSAGES...
- Breezy today with gusts of 30-40 mph (strongest west of
  I-29). Strongest winds will be a bit offset from areas with
  the lowest relative humidity (around 30% along and east of
  I-29), but an elevated fire danger can be expected this
  afternoon and evening.
- Generally above normal temperatures persist into this weekend.
  Normal to a bit below normal temperatures expected next week.
- Rain chances increase (40-70%) Saturday night into Sunday
  with the passage of a cold front. A few rumbles of thunder are
  possible with this activity, but severe weather is not
  expected.
&&
.DISCUSSION...
Issued at 405 AM CDT Sat Oct 11 2025
A few showers are showing up on radar west of the James
River this morning, but most if not all of this activity is not
reaching the ground as there is a rather deep, dry sub-cloud layer
in place across the area. This will be the trend through the day as
a weak upper-wave moves across the area associated with its parent
trough located over the Pacific Northwest. Cloud cover associated
with this wave will help limit high temperatures a bit, but
temperatures will still be mostly above average due to increasing
southerly flow at the low-levels of the atmosphere. Highs will be in
the upper-60s to mid-70s. Speaking of increasing southerly flow,
winds will pick up through the day as the SPG tightens between a
high pressure system to our northeast and a developing low to our
west. Wind gusts will steadily increase through the morning from
west to east, with peak gusts around 40 mph, strongest in central
South Dakota. Farther east, less breezy but still could see gusts in
the 30-35 mph range by the afternoon and evening. Elevated fire
weather conditions are expected area-wide due to gusty winds. RH
values will be lowest (around 30%) along and east of I-29, which is
where winds will be a bit lighter. So that`ll help prevent a more
significant fire weather threat from developing, but it will be
something to keep an eye on.
A second upper-wave will move through the area tonight from west to
east and bring an additional chance of rain to our area. Soundings
still indicate a layer of dry air the falling raindrops would have
to battle, but with a southerly LLJ peaking around 50-60 kts, should
be able to moisten the low-levels enough to allow for more of this
rain to reach the ground. The intensity on the ground may still not
match what the radar may suggests tonight, but should get better
ground coverage than compared to the daytime hours. Winds will still
be strong overnight, with gusts up to 30-35 mph possible as
temperatures only drop to the upper-50s to mid-60s. Winds on Sunday
will be breezy again, with gusts up to 35-40 mph as the LLJ is still
cranking. Winds should gradually lessen by the late afternoon and
evening as the LLJ begins to finally settle down. Highs on Sunday
will be a lot warmer with continued strong, southerly flow as
temperatures climb to the mid-70s to low-80s. The aforementioned
Pacific Northwest trough will begin to eject across the northern
Plains tomorrow, and at the surface we will have a low pressure
system over North Dakota and its cold front draped across the
northern and central Plains. After showers from the second upper-
wave move across the area tomorrow morning, we will begin to see
additional development along the cold front by the mid-afternoon.
Can`t rule out some isolated thunder with any activity Saturday
night into Sunday as there will at least be some limited elevated
instability. Severe weather is not expected.
Any showers/storms will exit off to our east with the frontal
passage tomorrow night, and cooler air will be ushered in heading
into Monday. Highs on Monday look to be in the upper-50s to mid-60s
(interestingly enough, the same temperatures as the morning LOWS
Sunday!). Guidance indicates the potential for additional upper-
waves to move-in mid-week before another Pacific Northwest trough
moves east across the Rockies into the Plains. Guidance does differ
in timing and location of this next main trough, so low-confidence
rain chances at this point continue into the end of the week. As of
now, the best rain chances next week look to be on Tuesday (20-40%
chance). Temperatures look to stay near to below normal through the
first half of next week, before another slight warm-up potentially
occurs to end next week.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1232 PM CDT Sat Oct 11 2025
Mostly VFR conditions will persist this TAF period. Taking a
look at satellite imagery, mid-level clouds continue to progress
through the area this afternoon with a few pockets of scattered
sprinkles to light showers. While these conditions likely stick
around for the next few hours, should see things clear out by
this evening. Additional chances for showers will be possible
overnight as the LLJ strengthens leading to some LLWS at each of
our TAF sites. Otherwise, breezy southerly winds will continue
into the overnight hours before becoming more northwesterly by
Sunday afternoon to end the TAF period.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...Samet
AVIATION...05

NWS FSD Office Area Forecast Discussion