534 
FXUS63 KFSD 031055
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
555 AM CDT Fri Oct 3 2025

.KEY MESSAGES...

- Well above normal temperatures continue through Saturday. A
  few record high temperatures and warm low temperatures are
  possible today-Saturday. Widespread moderate to locally major
  Heat Risk due to the unseasonable heat.

- Hot, dry and breezy to windy afternoons will lead to elevated
  fire weather conditions today (localized) and Saturday (more
  widespread with stronger wind). Use caution to avoid sparking
  fire in dry crops and grasses as rapid spread is possible.

- Rain chances for the latter half of the weekend are trending
  lower/farther west, with <20% chance of rainfall exceeding
  0.10" in our forecast area through Sunday night. 

- Near normal daytime highs return early-mid next week, with
  low-moderate rain chances (30-40%) focused toward Sioux City
  to Storm Lake Monday morning.

&&

.DISCUSSION...
Issued at 405 AM CDT Fri Oct 3 2025

TODAY-SATURDAY: Anomalously strong mid-upper level ridge remains
across the Plains and Upper Mississippi Valley today, shifting 
slightly east Saturday as a trough and corresponding cold front 
begin to move into the High Plains/western Dakotas. Bubble of
warm air beneath the ridge will lead to a couple more very warm
to unseasonably hot days as daytime temperatures climb into the
upper 80s to lower 90s. Dew points could be on the humid side
this morning in the lower 60s, but expect some mixing to bring
those values down a bit during the hours of peak heating. That
said, given that these temperatures are near record levels for
early October, Moderate (Level 2 of 4) Heat Risk is forecast
across most of the area today and Saturday. This could impact 
those more sensitive to heat such as older adults and infants, 
and potentially athletes and outdoor workers, especially those 
without effective cooling and/or hydration. Take precautions if
attending or participating in area sports today or Saturday.

Increasing southerly winds may provide a bit of relief from the
daytime heat, but will bring additional concerns with regard to
fire weather. More detail on that in the FIRE WEATHER section of
this discussion. In general, though, our light/variable winds
this morning will turn southerly by late this morning, with
gusts 20-30+ MPH by mid-late afternoon. The winds ease a bit
through the nighttime hours, but are expected to remain breezy
enough to hold lows in the mid 60s to around 70. This will lead
into an equally warm but even windier day Saturday as a 40-45kt 
low level jet shifts into our forecast area. Efficient mixing in
the low level south-southwest flow could mix gusts of 35-45 MPH
to the surface Saturday afternoon, likely remaining just below
advisory levels in most areas. 

SATURDAY NIGHT-MONDAY: The aforementioned upper trough and cold
front begin to move into our far western counties Saturday night
which could trigger a few showers/isolated storms. However, the
latest model trends focus better rain chances west through north
of our forecast area, with locations west of I-29 perhaps seeing
a few hundredths of rainfall Saturday night. This westward trend
and general lack of sufficient instability did result in the SPC
Day 2 outlook being scaled back to west of our CWA for Saturday
night. The cold front then slowly moves east across the forecast
area on Sunday-Sunday evening, but limited forcing/moisture will
again keep rainfall chances very low. Aside from the wind shift
associated with the front, the most notable change will be the
cooler temperatures. Still some uncertainty regarding the exact
timing of the front, but generally speaking, locations behind
the front by Sunday afternoon could see highs 15-20F cooler than
Saturday, while areas still ahead of the front could still climb
into the lower-mid 80s. Winds will be less gusty with a weaker
gradient along the front, though still breezy with gusts 20-30
MPH as winds swing from southwest to northwest. 

The low level front hangs up just south of our forecast area by
early Monday, which brings a low-moderate (30-40%) chance for 
light rain showers to southeast portions of the CWA Monday 
morning, mainly south of Highway 18.

TUESDAY ONWARD: The pattern becomes a bit more muddled through
the midweek period, especially by Wednesday and Thursday as
models diverge on development of a potential trough to our west.
Depending on the timing/strength, we could see some light rain
chances by the end of this forecast period on Thursday. Prior to
then, however, focus will be on temperatures which are much
closer to seasonal normals, with a day or two of highs only in
the 60s. A backdoor cold front drops into North Dakota/northern
Minnesota Tuesday-Tuesday night, and with a surface high in our
area providing mostly clear skies/light winds, may have to watch
our nighttime lows Tuesday night/early Wednesday for a bit of
frost. However, better chances currently look to remain north of
Highway 14.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 555 AM CDT Fri Oct 3 2025

VFR conditions will prevail through this TAF period. Areas of 
mid-level clouds (at/above 10kft AGL) move across the forecast 
area this morning, and may return again late in the period. 

More notable for this TAF period will be development of gusty
southerly winds today, with afternoon gusts 20-30kt, strongest
west of U.S. Highway 281. Gusts ease a bit after sunset, but
will not diminish completely as a 40-45kt low level jet develops
overhead. This will lead to a period of low level wind shear
after 03Z-05Z for most areas.

&&

.FIRE WEATHER...
Issued at 405 AM CDT Fri Oct 3 2025

Increasing southerly winds today and Saturday will bring some 
fire weather concerns to the area as we head into the first
weekend of October. Today will see winds gusting 20-30 MPH in
most areas by this afternoon, with some higher gusts near 35 MPH
west of the James River Valley. Well above normal temperatures
approaching 90F this afternoon modest humidity levels (as low as
30-40%) will generally lead to Moderate to High Grassland Fire
Danger. However, fully cured crops and/or grasses could see
localized Very High fire danger conditions and caution is
advised when working in these drier areas.

Saturday brings greater concerns as the south-southwest winds
strengthen further. Late morning to early evening gusts of 35
to 45 MPH will be more common, with humidity levels falling as
low as 25 to 35 percent (perhaps lower if mixing is even more
efficient). This will lead to more widespread High to Very High
Grassland Fire Danger in the greener grasses. However, the drier
grasses and especially crops would be susceptible to rapid fire
spread (localized Red Flag conditions possible), as marginal 
humidity levels could easily be overcome by the stronger winds 
currently forecast. With this in mind, farmers and others 
working outdoors will need to be mindful of their equipment 
usage to avoid sparking a fire in the dry fuels.

&&

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

&&

$$

DISCUSSION...JH
AVIATION...JH
FIRE WEATHER...JH