446
FXUS63 KFSD 222345
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
645 PM CDT Sat Jun 22 2024

.KEY MESSAGES...

- Ongoing flooding may worsen as the runoff from the last 24
  hours makes its way to the waterways. Record river flooding
  is likely on several basins.

- Dry conditions with seasonal temperatures are expected Sunday,
  however a hot and humid air mass returns on Monday. Monday
  high temperatures are expected to rise into the 90s with heat
  indices nearing or exceeding 100 degrees, especially for the
  SD/NE/IA tri-state region.

- The pattern through mid week doesn`t favor any long duration
  rain, but several brief risks for passing convection exist. A
  more prominent low pressure system moves in later in the week
  and weekend.

&&

.DISCUSSION...
Issued at 220 PM CDT Sat Jun 22 2024

Shortwave energy responsible for morning/early afternoon
convection continues to exit the region, although can`t rule
out an isolated diurnally driven shower or thunderstorm over
parts of south central South Dakota this evening. Otherwise,
high pressure and large scale subsidence is expected for the
overnight hours and into Sunday, resulting in dry conditions.

The progressive upper level pattern will continue into next
week. Another low pressure system will develop out of the
Rockies on Monday. Return flow winds and strong WAA advection is
expected out ahead of the system Monday afternoon. Model
dew point temps rise back into the upper 60s/low 70s with NBM
giving a 99% probability of CAPE values soaring above 2000 J/KG.
That said a healthy CAP and lack of forcing should prevent
thunderstorm activity during the afternoon hours. Afternoon max
temperatures will be on the rise, with highs into the 90s.
Combined with humidity, apparent temperatures will be nearing or
exceeding 100 degrees in some locations, especially along and
south of I90. 500 MB height falls/shortwave energy are more
prominent during the late Monday night into Tuesday morning time
frame however. A low POP exists in this time frame and the
region is outlooked for a marginal (1 out of 5) chance for
severe weather.

High pressure will again build in for Wednesday. However, the
end of the workweek appears to be active once again. Near zonal
upper level flow on Thursday will transition to southwest flow
aloft for Friday and into the weekend. This pattern will again
set up the return flow/gulf moisture tap and WAA on Thursday
with a fairly well organized low pressure system moving through
Friday and Saturday. Multiple rounds of showers and
thunderstorms are possible.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 641 PM CDT Sat Jun 22 2024

While the majority of the period will see VFR conditions, later
tonight into Sunday morning some patchy fog, especially between
the James River towards I-29.

&&


.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch until 7 PM CDT this evening for SDZ062-067.
MN...Flood Watch until 7 PM CDT this evening for MNZ081-089-090-098.
IA...Flood Watch until 7 PM CDT this evening for IAZ001>003-012>014.
NE...None.

&&

$$

DISCUSSION...Serr
AVIATION...08