056
FXUS63 KFSD 180810
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
310 AM CDT Thu Jul 18 2024

.KEY MESSAGES...

- A few isolated sprinkles to light showers will be possible in
  our southcentral SD counties this morning with only light
  accumulations expected.

- More rain chances (30%-60%) will likely return over the
  weekend with the better chances expected from Friday afternoon
  through Friday night. While the exact timing and location of
  developing storms remains questionable, an isolated severe
  risk with pockets of heavy rainfall remain possible during the
  period.

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

&&

.DISCUSSION...
Issued at 305 AM CDT Thu Jul 18 2024

TODAY & TONIGHT: Another mostly quiet day will be on tap for
the day! Taking a look across the area, mostly clear conditions
continue as the surface high sits overhead. Light and variable
winds along with lingering low level moisture could lead to the
development of some patchy areas of fog this morning mostly
across our River Valleys and portions of northwestern IA. While
the fog shouldn`t stick around long, expect it to gradually
erode as mixing restarts. Looking back to our southcentral SD
counties, a few light showers will be possible around daybreak
as a subtle shortwave interacts with a couple hundred Joules of
instability. While widespread development is not expected,
decided to add in some smaller POPs (<20%) in Gregory county to
capture the potential. Besides that, conditions will be very
similar to yesterday with highs topping out the mid to upper 70s
and low 80s with light southeasterly winds for the day. By
tonight, expect mostly quiet conditions to continue as warm air
advection (WAA) strengthens on the backside of the departing
mid-level ridge setting the stage for our next precipitation
chances heading into Friday. With this in mind, expect our
temperatures to slight rebound overnight as lows only decrease
into the upper 50s and low 60s.

FRIDAY-SUNDAY: Heading into the weekend, the main concern
continues to be the increasing rain chances (30%-60%) as a
strengthening northern stream wave dives into our area from
eastern Wyoming. Starting with Friday, increasing WAA aloft
along with southerly surface winds will help temperatures climb
into the upper 70s to mid 80s for the day. From here, our
attention will turn to northwest as the chances for scattered
shower and thunderstorms increase by Friday afternoon as the
wave approaches. While some lingering uncertainty continues with
the timing and location of developing activity, modest
instability values (1000-1500 J/kg) and 25-35 kts of deep layer
shear could support an isolated severe weather risk especially
west of the James River Valley with the primary hazards being
large hail and damaging winds as multicellular storms grow
upscale into linear segments. From here, the threat likely
transitions to pockets of heavy rainfall as PWATs increase
towards 1.50-1.75 inches heading into the evening and overnight
hours. By Saturday, the wave will continue to progress
southeastwards stalling somewhere across eastern Nebraska and
western Iowa bringing continued chances for showers and
thunderstorm across parts of our area through Sunday. With all
this in mind, most areas can expect rainfall accumulations of up
to half an inch through Sunday with pockets of up to an inch
possible along the Missouri River Valley. Lastly, with increased
precipitation chances through Sunday, expect our temperatures
to top out in the mid to upper 70s and low 80s.

MONDAY-WEDNESDAY: Looking into the start of the new week, an
active pattern will continue aloft as upper-level ridging
continues to build across the western CONUS. As a result,
intermittent periods of scattered showers and isolated
thunderstorms will be possible through Wednesday. Lastly, with
multiple precipitation chances ahead; expect our temperatures to
stay near to just below our seasonal normals through the
midweek with highs in the upper 70s to low 80s expected.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1042 PM CDT Wed Jul 17 2024

VFR conditions are expected to prevail this TAF cycle. Should see
light and variable winds continue for much of the overnight period,
with direction turning more southerly by mid-morning. Otherwise,
expect chances for scattered showers and storms return by the end of
the period, mainly along and west of the James River Valley.

&&

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

&&

$$

DISCUSSION...Gumbs
AVIATION...SST