Brandon, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

551
FXUS63 KFSD 081055
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
Issued by National Weather Service Aberdeen SD
555 AM CDT Tue Apr 8 2025

.KEY MESSAGES...

- Low chances for moisture (20-30%) Wednesday/Thursday. Total
  rainfall range between 0.01 - 0.10 inches.

- Mild late week/weekend! 60s Friday (5-10 degrees above normal) and
  70s/80s Saturday and Sunday (15-20 degrees above normal).

- Showers return Sunday/Monday, though considerable uncertainty
  remains with regards to chances.

&&

.DISCUSSION...
Issued at 244 AM CDT Tue Apr 8 2025

A short lived ridge aloft will be responsible for clear skies today
but that will give way to increasing clouds and low chances for
moisture. Thats because a 110kt jet directed into
Oregon/Northern California will gradually propagates eastwards
towards South Dakota with the left exit region helping to
support a wave up along the Montana/North Dakota/Canadian
border. That wave drops southeast across North Dakota, northeast
South Dakota into southern Minnesota Wednesday. While there is
an initial broad elevated push of moisture at 10kft with these
features, NAM BUFKIT profiles suggest is a deep dry subcloud
layer below 8kft. As it takes a few hours to saturate down
according to those same soundings...between 06Z and 12Z
Wednesday from west to east, moisture aloft becomes much less
consistent. This general disorganization continues through
Wednesday into early Thursday. Low level flow shifts to
northwesterly early Wednesday, as a surface low moves across
Nebraska. Initially not much cold advection across the area,
however that will increase as winds become more northerly
Wednesday night. Unidirectional shear for the day will result in
increased winds and mixing, though BUFKIT mixed winds are only
topping out around 25kts during the day Wednesday.

As for moisture potential, its looking like this disorganized system
will bring little if any at all. The probability for 0.10" has
fallen to 5-10%, with just a 20-40% chance for just measuring.

Low stratus and weak cold advection comes in for Thursday, limiting
diurnal heating. NBM 25th/75th percentiles have an 8 degree
range for highs from Sioux Falls to Chamberlain and points
north.

Friday, low level return flow and an upper ridge with drier air
aloft will translate into a gradual warming trend. 850mb temperatures
increase, peaking at a standard deviation above climo (2 standard
deviations for 700mb temperatures) Saturday/Sunday. NBM mean is
now suggesting we could see spots break 80F both Saturday and
Sunday. The probability of exceeding 80F Saturday:
Chamberlain 60%, Sioux Falls 20%. The probability of exceeding
80F Sunday: southeast South Dakota 60%, northwest
Iowa/southwest MN 50% and 40% respectively. The one caveat is
there will be some high clouds spilling over the ridge which may
impact insolation.

Sunday/Monday we see the ridge break down in response to an incoming
upper wave. Over the last few nights, deterministic models have
been fairly in-line each night but between runs there have been
several different iterations on its evolution, so while there
is some confidence for a transition how it will actually play
out is still uncertain. The latest pattern evolution is that the
ridge gives way to an upper trough/low that is now stronger in
the northern stream, that traverses west to east across the
Dakotas/Minnesota. Still seeing some CAPE show up in NBM, with
the 25th/75th ranging between ~100 to near 500j/kg. The setback
here is that NBM dewpoints remain in the 30s/40s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 551 AM CDT Tue Apr 8 2025

VFR conditions for all terminals. Winds will eventually becomes
more uniformly southeasterly and remain through the TAF period,
though we will see a shift to northwesterly at or just after
the 12Z end of TAFs timeframe. Otherwise just expecting a deck
of mid level clouds AOA 8kft.

&&

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

&&

$$

DISCUSSION...MC
AVIATION...MC