455
FXUS63 KFSD 160836
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
336 AM CDT Tue Jul 16 2024

.KEY MESSAGES...

- Scattered showers with isolated thunderstorms will be
  possible through this evening. An isolated severe weather risk
  will be possible mostly across our southcentral SD counties.

- Near to below normal temperatures will continue through the
  weekend as cooler air funnels into the region.

- Confidence continues to grow in more widespread rain chances
  over the weekend. However, the details remain far from
  certain.

&&

.DISCUSSION...
Issued at 335 AM CDT Tue Jul 16 2024

The Short Term (Today & Tonight):

A cooler day is ahead! Taking a look across the area, cooler air
continues to funnel into the region behind yesterday`s cold front.
As a result, many area`s will wake up to temperatures in the low to
mid 60s to start the morning as a surface high gradually sides into
the area. Looking a radar, a few scattered showers continue to
develop across portions of western ND and southcentral SD in
response to bits of isentropic lift associated with the rotating
Hudson Bay trough in Canada along with support from the right
entrance region of an upper-level jet. While these developing
showers could make it into areas west of the James River and north
of I-90 this morning, the general expectation is for these showers
to gradually dissipate by the early afternoon as they approach the
more stable airmass (surface high) sitting over our area.
Nonetheless, lingering CAA advection along with light northeasterly
flow will likely help our temperatures below or seasonal normals for
the day as highs only reach the mid to upper 70s to low 80s with the
warmest conditions along the Missouri River.

Our focus will likely turn to the Missouri River Valley by the early
afternoon as a few isolated showers and thunderstorms develop ahead
of a subtle shortwave diving into southcentral NE. While the better
convective chances will likely occur just south of our area in
southcentral NE, there is a narrow but decent chance for an isolated
stronger storm or two over our southcentral SD counties closer to
21z. With up to 1500-2000 J/kg of MLCAPE and 35-40 kts of deep layer
shear to work with, developing storms could quickly become severe
with large hail up to golf ball size and damaging winds up to 60 mph
possible. With all this in mind, SPC continues to outline the
Missouri River Valley in a Marginal Risk (Level 1 of 5) for severe
weather. From here, expect any developing activity to progress
southeastwards before dissipating this evening. Lastly, expect a
cooler night as cooler air continues to makes it way to the surface.
With this in mind, overnight temperatures will gradually decrease
into the mid to upper 50s and low 60s for the night.

The Long Term (Wednesday-Monday):

Heading into the midweek, much quieter conditions will continue
through Thursday as mid-level ridging quickly moves in to replace
the departing upper-level wave. With lingering cold air advection
aloft and ample mixing at the surface, expect temperatures to
continue their cooling trend through Thursday as highs gradually
decrease into the low to upper 70s and low 80s on both days
with overnight lows in the 50s to low 60s. By Friday, a warm
nose will begin to develop on the backside of the mid-level
ridge as 850 temps approach 20 degrees C. While this won`t
likely translate to increased surface temperatures, the warm
mid-level will likely serve as fuel for the approaching clipper
wave as it dives southeastwards into our area from the
international border.

Intermittent periods of scattered showers and thunderstorms will
likely develop from Friday into Saturday as the open wave wraps up
into a closed low. With borderline convective temperatures and long-
skinny CAPE profiles (500-1000 J/kg); the severe weather threat
should be rather limited. However, PWATs up to 1.75 inches and warm
cloud layer depths of up to 11kft do suggest the potential for
pockets of heavy rainfall. With all this in mind, a wet and dreary
weekend is ahead to say the least. As the closed low begins to drift
southwards by Sunday expect any lingering activity to gradually
dissipate throughout the day with much quieter conditions expected to
return by Monday. Lastly, with the increased precipitation chances
over the weekend; highs will likely continue to hover just below
normal with temperatures in the mid to upper 70s and low 80s
expected.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1039 PM CDT Mon Jul 15 2024

VFR with light and variable winds expected for the overnight period,
with areas west of I-29 possibly seeing some scattered
showers/storms in the morning hours. Another round of scattered
showers/storms are expected in the afternoon hours moving from north
to south, with VFR conditions expected outside of thunderstorms.
Winds on Tuesday will remain fairly light, with direction a little
variable but predominantly out of the north.

&&

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

&&

$$

DISCUSSION...Gumbs
AVIATION...APT