200
FXUS63 KFSD 020539
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1139 PM CST Sun Nov 1 2026

.KEY MESSAGES...

- Light to moderate rain showers will spread across the entire
  region through the overnight. Rain will lessen briefly Monday
  afternoon before increasing again from west to east overnight
  into Tuesday morning. Low stratus may lead to visibility
  lowering to 2 miles or less at times.

- Severe weather is not anticipated at this time. However, some
  isolated funnels are possible Monday afternoon.

- By the time rain ends Wednesday afternoon, widespread
  accumulations of 0.50 to 1.00 inches are expected for most of
  the region. Along and north of a line from Chamberlain,
  Mitchell, and Brookings will see the highest totals, up to 1.5
  inches with isolated 2+ inch pockets possible.

- Gusty winds are expected on both Monday and Tuesday with
  widespread gusts of 30-35 mph. Locally higher gusts of 40-45
  mph will be possible, mainly through eastern South Dakota.

&&

.UPDATE...
Issued at 942 PM CST Sun Nov 1 2026

Current radar is showing weak echos (<25 dBZ) across much of western
and central South Dakota. Looking aloft we see southwesterly flow,
the exit region of a jet streak, and overall divergence. To the west
over the Rockies we see a deep upper trough and a lee surface low
pressure forming over eastern CO, western KS and NE. The whole
system will accelerate northeast through the overnight with a
trailing cold front. Strong and deep warm air and moisture
advection from the surface through the mid-levels will help to
thicken and lower stratus over the region. Though winds will be
too strong for true fog formation, soundings indicate the
boundary layer will saturate to nearly the surface. Ensemble
guidance indicates a 20-40% probability for visibility to fall
to 2 miles or less at times through Monday morning. Frontogenesis
in the mid- levels intensifies as does the surface pressure
gradient. A very strong 50-60 kt LLJ will result. With ample
forcing for ascent the current light showers will gradually
intensify to light to moderate rain showers with isolated
thunderstorms possible. Severe weather concerns are low at this
point, with less than a 5% probability. Though 0-6km bulk shear
is sufficient at 35-40 kts, moderate to strong capping is in
place, lapse rates are weak at 6 deg C/km or less, and
instability is low at just 100-500 J/kg. Still, a few stronger
thunderstorms could produce brief heavy rainfall. Additionally,
with very low LCLs and enhanced vorticity and stretching
potential a few funnels are possible in the afternoon.

In addition to showers and thunderstorms winds will increase
overnight, becoming strong by mid-Monday morning. Winds will be
southeast sustained at 20-25 mph and gusts 30-35 mph. A few
gusts up to 40 mph are possible, mainly along the SD/NE border.
Strongest winds will be east of the James River, and west of
I-29.

Light to moderate rainfall is expected to continue through the
overnight into Monday morning. Shortly after daybreak there are
indications that a dry slot may begin to slide into south central
South Dakota. As this progresses northeast with the whole system,
showers will become light and more scattered in nature. Periodically
changing to drizzle or ceasing altogether. Scattered light showers
and drizzle continue through Monday afternoon. By Monday evening
wrap around showers begin to enter the western portions of our CWA.
This round of showers will be lighter than the previous but will
move slowly through the region, ending Wednesday afternoon. By
the time rain ends total accumulation will range from 0.50 up to
1.00 inches for most of the CWA. Areas along and north of line
from Chamberlain, Mitchell, and Brookings will see the highest
totals up to 1.5 inches. NBM 75th percentile indicates pockets
of 2+ inches are possible in this area, should stronger storms
develop or move slower than anticipated.

&&

.DISCUSSION...
Issued at 218 PM CST Sun Nov 1 2026

CURRENTS & TONIGHT: Taking a look across the area, a dreary start to
November continues as areas of low stratus and mid-level clouds sit
over the area. While some thinning and southeast surface winds may
help temperatures sneak into the upper 50s to mid 60s this
afternoon, should see holes fill back in by this evening as warm air
advection (WAA) strengthens. Similar to last night, decided the
dynamics at play will likely slow cooling overnight so used a blend
of the CONSshort and NBM to slightly increase temperatures to the
mid to upper 50s. From here, the focus will then shifts towards the
increasing rain chances (70%-100%) this evening and overnight.
Looking aloft, a strengthening nocturnal LLJ along with
increasing lift ahead of the approaching wave will likely spur
bands of light showers starting this evening. Lastly, the SPG
will continue to tighten heading into Monday morning leading to
gusts between 30-40 mph throughout the day. With this the stage
is set for Monday`s Colorado Low.

MONDAY-WEDNESDAY: Looking into the new week, we`re still on track
for widespread rain on Monday as the developing Colorado Low lifts
into central and eastern SoDAK from the Nebraska Panhandle. From
here, not much has changed on the forecast front. Bands of light to
moderate showers will develop during the morning hours giving us
most of our accumulations. Still can`t rule out a few isolated
thunderstorms mainly across areas along and east of Highway-81 as
about 300-500 J/kg of instability develops. A dry slot will
gradually progress across the area from late morning to early
evening potentially switching us over to drizzle or just mostly dry
conditions temporarily. Next round of precipitation comes by Tuesday
morning as the 850mb cold front and surface low progress through the
area. Depending on how and if things develop around the surface low
during this time, we might have to be on the look out for a few
funnels given the enhanced stretching potential with the low and
lower LCLs. This is particularly evident in the NAM and RAP13 NST
which has scattered values in the 0.5 to 1.5 range.

A tight SPG will continue to promote breezy to strong surface winds
on Tuesday with northwesterly winds behind the front producing gusts
between 30-40 mph with isolated higher across southcentral SD.
Otherwise, should see light showers hang around for most of Tuesday
and into potentially Wednesday as the mid-level low continues to
gradually rotate eastwards into Minnesota. Shifting gears to overall
amounts, some lingering uncertainty remain on where the heaviest
accumulations will occur. However, guidance has shown consistent
enough signals for a widespread 0.75" to 1.25" inches through at
least Tuesday. Nonetheless, there still could be an area of slightly
higher amounts (1"-2"+) potentially west of a Gregory to Mitchell to
De Smet line depending on how the low tracks through the region.
Impact-wise, lower precipitation rates will keep the flooding
concerns on the lower side through the period though localized
ponding will be possible in the area of heaviest accumulation and
low-lying spots. Lastly, the increased precipitation  chances
will trend conditions cooler through Wednesday. As a result,
highs are expected to tumble from the 60s to low 70s on Monday
to mid 40s to low 50s by Wednesday.

THURSDAY ONWARDS: Heading into the later parts of the week, quieter
conditions return by Thursday as mid-level ridging progresses
through the region. Next potential rain chances return by Saturday
as a quick and compact wave dives across the northern plains.
Otherwise, daily temperatures will continue to hover in a more
seasonable range with highs mainly in the low to mid 50s and
overnight lows in the upper 30s to low 40s.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1127 PM CST Sun Nov 1 2026

A mix of VFR down to LIFR ceilings will prevail for the first half
of this period. Ceilings will continue to degrade to mainly IFR with
periods of LIFR under showers and thunderstorms. Soundings indicate
stratus will slowly lower as the boundary layer saturates, down to
near the surface. Though winds will likely remain too strong for
true fog formation, ensemble guidance indicates a 20-40% probability
that visibility may fall to 2 miles or less at times.

Light to moderate rain showers currently located west of I-29 will
continue to move northeast through the overnight. A few stronger
storms may produce lightning and brief heavy down pours. Severe
weather is not anticipated. A dry slot pivots through the region
beginning around mid-day over south central South Dakota. Showers
and storms will lessen in intensity to light rain/sprinkles to
drizzle, if not ceasing all together at times. During the afternoon
ceilings are likely to improve back to MVFR before another round of
wrap around showers moves in Monday evening.

Southeasterly winds are expected to increase overnight. By mid-
morning winds will be gusting 25-35 kts with the strongest gusts
east of the James River Valley and west of I-29. Gusty winds
decrease temporarily ahead of the approaching cold front Monday
evening.

&&

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

&&

$$

UPDATE...AJP
DISCUSSION...05
AVIATION...AJP