619
FXUS63 KFSD 260329
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1029 PM CDT Tue Jun 25 2024

.KEY MESSAGES...

- River Crests have already occurred or will occur within the
  next 24-48 hours.

- An active pattern aloft will bring in multiple rain chances
  through the area throughout the week with the most widespread
  chances expected on Thursday and Friday.

- Rain probabilities remain focused below 1 inch in most
  locations at the end of the week.

&&

.DISCUSSION...
Issued at 306 PM CDT Tue Jun 25 2024

The Short Term (Rest of the Afternoon/Tonight):

A slightly cooler and mostly quiet day will continue. Taking a look
across the area, mostly clear conditions continue as our current
observations show pleasant temperatures in the low to mid 80s as of
19z. With light winds and lingering cold air advection (CAA) aloft,
expect our highs to vary between the low to upper 80s and low 90s
with the warmest conditions expected across the Missouri River
Valley. While the pleasant conditions will likely continue through
the early afternoon, our focus will likely shift towards our
precipitation chances as a subtle shortwave kicks off some isolated
showers and thunderstorms along the Missouri River and Hwy-20
corridors.

Looking at the environment, warm and moist air will aid in the
develop of 2000-3000 J/kg of MLCAPE along with 30-40 kts of deep
layer shear across areas along and south of I-90. Without much
of a cap today, developing air parcels could quickly become
strong to severe quickly with large hail up to 2 inches and
damaging winds up to 70 mph being the primary threats. While the
potential is low, an isolate tornado isn`t completely out of
the question either. Nonetheless, the severe threat to continue
through about 06z before dissipating. Otherwise, could see some
lingering showers continue through tonight as the LLJ slight
strengthens. Nonetheless, accumulations up to a two tenths will
be possible especially along the Missouri River Valley. Lastly,
seasonal temperatures are expected overnight as lows drop into
the low to mid 60s for the night.

The Long Term (Wednesday-Monday):

Heading into the extended period, quieter conditions will
temporarily return by Wednesday as mid-level ridging approaches from
the west. Light northerly surface winds along with lingering cold
air advection (CAA) aloft will lead to slightly cooler temperatures
for the day with high only expected to peak in the upper 70s to low
80s. With that being said, If you have any outdoor work or
activities that you would like to complete; this will likely be the
best overall day to get things done heading into the weekend.
Looking aloft, our attention will shift to the Colorado Rockies by
Wednesday night as a mid-level wave ejects eastwards into the
northern and central plains. As WAA strengthens out ahead of a warm
front situated somewhere over west central SD, scattered showers and
thunderstorms will likely develop over the western portions of the
state and track eastwards into our area. However, with the better
corridor of instability expected to stall over central SD with the
warm front; some uncertainty still remains on the severity of the
incoming showers and storms. Nonetheless, elevated PWATs up 1.75
inches and warm cloud depths above 10kft could lead to some pockets
of heavy rainfall as developing convection crosses into our area.
Lastly, accumulations up to a quarter inch possible heading into
daybreak on Thursday morning with the heaviest accumulations
expected west of the James River.

Looking into Thursday and Friday, lingering showers will continue
during the day on Thursday as the previously mentioned wave
traverses our area. From here, deterministic guidance is a bit split
on if we get a temporally lull in activity or not before the next
round of showers and storms develop. Either way, Thursday looks to a
cool and dreary day as highs only reach the low to upper 70s for the
day. By Thursday night, our attention will pivot to the Rockies as a
more robust mid-level wave swings through the region along with its
associated cold front bringing widespread precipitation chances.
While there is still much uncertainty regard the severe weather
potential for this event, PWATs up to 2 inches and a warm cloud
layer above 10kft give decent signals for periods of heavy rainfall
with greatest area of concern being over portions of Iowa. With this
in mind, our area could see intermittent periods of light to
moderate showers with a few isolated thunderstorms through late
Friday morning. Accumulations will vary over the area, but ensemble
continues to show low to medium confidence in up to half an inch of
QPF across the area. Otherwise, mostly quiet conditions will return
for the rest of the weekend as upper-level ridging builds across the
area through Monday. There will be a chance for more precipitation
on Monday. However, with timing and intensity differences among
guidance; decided to leave the default NBM in for this time period.
Lastly, after near normal temperatures on Friday; our temperatures
should noticeably decrease through Sunday with highs expected to
peak in the mid to upper 70s for the day.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1026 PM CDT Tue Jun 25 2024

Lingering convection along the Missouri River will gradually
dissipate by midnight, leaving VFR conditions across the Tri-
State are into Wednesday morning. A few scattered showers or
sprinkles move through by mid-morning Wednesday.

Afternoon conditions will be warm and dry with scattered diurnal
CU.


&&

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

&&

$$

DISCUSSION...Gumbs
AVIATION...Dux