144
FXUS63 KFSD 020401
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1001 PM CST Sun Nov 1 2026

.KEY MESSAGES...

- Periods of rain return tonight into mid week, heaviest tonight
  into Monday. Accumulative amounts of 0.75" to 1.25" inches are
  expected for most areas through Wednesday night. Slightly higher
  amounts will be possible west of a Gregory to Mitchell to De
  Smet line. Locally heavy rain may lead to ponding of water.

- Breezy to gusty winds are expected on both Monday and Tuesday
  with gusts between 30 to 40 mph. Locally higher gusts (around
  45 mph) will be possible across south central South Dakota.

- A brief funnel or two could be possible by Tuesday morning
  though confidence is low (<30%).

&&

.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. 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 Tuesday evening. 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 /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 619 PM CST Sun Nov 1 2026

Currently a mix of VFR and MVFR ceilings across the entire region.
Expect ceilings to gradually decrease as continued moisture and warm
air advection work to thicken and lower the stratus already in
place. Overnight and into Monday morning widespread IFR and LIFR
conditions are expected as soundings indicate the boundary layer
saturating 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.

With the lowered ceilings come light to moderate rain showers.
Current radar shows echoes forming over central South Dakota. These
will progress east through the overnight. A few stronger storms may
produce lightning and brief heavy down pours. No severe weather is
expected at this time as the better dynamics exist farther south
over Nebraska and Kansas. But we will monitor for changes in risks.
Around mid-day a dry slot looks to pivot through the region. This
will reduce storms down to a light rain/drizzle if not cause them to
cease for a time. This may allow ceilings to improve back up to MVFR
in places. As moisture wraps around the low, rain will increase
again from west to east near the end of the period.

Winds are southeasterly and beginning to increase. Overnight gusts
of 15-25 kts are expected to gradually increase. Around daybreak
winds will be gusting 25-30 kts with the strongest gusts east of the
James River Valley and west of I-29. Gusty winds will prevail for
the remainder of the period.

&&

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

&&

$$

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