Brookings, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

734
FXUS63 KFSD 250313
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1013 PM CDT Thu Apr 24 2025

.KEY MESSAGES...

- Intermittent periods of light to moderate showers will
  continue through tonight. Additional accumulations between a
  0.10" to 0.50+" of an inch will be possible mainly east of
  I-29 with the highest accumulations across northwestern IA.

- Scattered showers and thunderstorms likely return between
  Sunday and Monday with a few storms becoming strong to severe.
  Continue to monitor the forecast for the latest information.

&&

.DISCUSSION...
Issued at 257 PM CDT Thu Apr 24 2025

CURRENTS & TONIGHT: A dreary day continues! Taking a look across the
area, light to moderate showers continue to develop and lift
northeastwards mostly in response to increasing lift and dPVA
associated with a approaching shortwave this afternoon. Expect this
developing activity to continue lifting into areas along and east of
U.S. Highway-81 over the next several hours potentially adding an
additional 0.10" to 0.50+" of an inch of rainfall across the
previously outlined areas with the highest amounts being focused
across northwestern IA. With some lingering instability (200-300
J/kg) above the boundary layer, can`t completely rule out a few
rumbles of thunder this evening in our southeastern-most counties
(Woodbury, Ida, Buena Vista, Cherokee, and Plymouth). However, with
the better instability just to our south and east any truly
organized thunderstorms will likely stay just south of the Highway-
20 corridor this evening. From here, expect the main batch of rain
to push out of the area closer to midnight tonight. Nonetheless,
could see a few more light showers through daybreak on Friday as a
subtle weak wave moves across the state with limited accumulations.
Lastly, overcast skies and lighter winds will likely keep our
overnight temperatures elevated with lows expected to be in upper 30s
to mid 40s with the warmest conditions across northwestern IA.

THE WEEKEND: Heading into the weekend, quieter conditions will return
by Friday as a strengthening ridge moves across the plains. Cloud
cover will gradually decrease throughout the afternoon as a
tightening SPG leads to breezy northerly to northeasterly winds with
gusts between 20-30 mph. As some weak warm air advection (WAA) moves
in aloft, will see conditions trend warmer compared to the previous
day as highs peak in the upper 50s to low 60s with the warmest
conditions along our River Valleys. Looking into the rest of the
weekend, periodic breeziness will continue on both Saturday and
Sunday as the SPG tightens leading to wind gusts between 25-35 mph
at times. Conditions will continue to trend warmer through Sunday
with highs expected to transition from mostly the 60s on Saturday to
the upper 60s to low 70s by Sunday. From here, our focus will shift
towards our rain chances (30%-40%) as southwesterly flow helps
ushers in a couple of waves into the region subtle on Sunday.

As increasing WAA interacts with the instability (<600 J/kg)
associated with the first approaching wave, could see a few
scattered showers develop mainly east of I-29 between the afternoon
to evening hours on Sunday. However, with limited moisture according
to soundings, not expecting much in terms of accumulations with this
activity. This sentiment is further echoed in the ensembles with
most models only showing moderate confidence (40%-60%) in measurable
precipitation. From here, our focus will turn to the Rockies as a
positively-tilted trough ejects into the central and northern plains
by Sunday night into Monday. Could see some scattered showers and
thunderstorms develop between midnight and daybreak on Monday mainly
west of I-29 as increasing lift ahead the wave interacts with the
nose of an upper-level jet. With long-skinny CAPE profiles and 30-
40kts of bulk shear in place, can`t rule out a few stronger "pop up"
storms that could produce some large hail stones. However, anything
that does develop would have to overcome a pretty good cap according
to soundings. Nonetheless, if the activity can somehow break through
and/or become more elevated the potential`s definitely there.

MONDAY ONWARDS: Looking into the new week, much warmer
conditions are expected by Monday as southwesterly flow
increasing WAA lead to temperatures in the upper 70s to mid 80s
with the warmest conditions across northwesterly IA. More breezy
conditions will be on tap as a tightening SPG leads to wind
gusts between 25-35 mph. From here, our attention turns our
afternoon/evening precipitation chances as the previously
mentioned system drags a cold front across the region. Looking
at the environment, southwesterly surface winds will continue to
pull in warm and moist air into the area during the afternoon
creating quite an unstable airmass ahead of the cold front.
While sounding continue to indicate that the environment will be
capped through 21z, most sounding also show a classic "loaded
gun" signature across areas east of I-29. As this cap erodes
with peak heating, any developing parcels would have access to
about 1500- 2000 J/kg of CAPE with around 50 kts of speed shear.


Now while the environment seems primed for severe weather, there is
still some uncertainty. The biggest concern is if the cold front
arrives later than expected (after 00z) like Euro/Canadian show. If
this were to happen, we likely wouldn`t get much with most guidance
showing the bulk of the activity developing east of us. However, if
things line up just right like the GFS shows; could see a few
stronger storms develop along the cold front mainly east of I-29.
Given the environment, large hail and damaging winds would be the
primary threats. With this in mind, the Storm Prediction Center
(SPC) continues to have areas along and east of highway-81 outlooked
in 15% with portions of northwestern IA and southwestern MN now
locked into a 30%. From here, expect most of this activity to leave
the area by the late evening hours. Lastly, quieter conditions
returns with milder conditions persists through Wednesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1009 PM CDT Thu Apr 24 2025

Light rain to drizzle will continue to move east through the
Tri-State area through early morning of Friday. Some visibility reductions
will be possible mostly in areas where moderate drizzle is
falling. However, latest guidance does begin to bring in drier
air and downward ascent which suggests that rain should be clear
of all but the far eastern CWA by daybreak.

Northerly winds will prevail through most of Friday, with only a
slow improvement in ceilings from IFR to MVFR and finally VFR by
the afternoon.

Skies are likely to clear by Friday evening.

&&

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

&&

$$

DISCUSSION...05
AVIATION...Dux