559
FXUS63 KFSD 110921
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
421 AM CDT Tue Jun 11 2024

.KEY MESSAGES...

-Any lingering showers activity will continue to push east this
 morning before exiting our area.

-While severe weather remains possible on Wednesday,
 uncertainty remains on exactly where storms will develop.

-Near to above normal temperatures will continue into the
 weekend with warmest day expected to be Wednesday.

&&

.DISCUSSION...
Issued at 415 AM CDT Tue Jun 11 2024

The Short Term (Today & Tonight):

Another warm and marginally breezy day is ahead. Taking a look
across the area, lingering light showers continue to push eastwards
ahead of a cold front roughly positioned along a Huron to Gregory
line. As this frontal boundary continue to sweep southeastwards
throughout the morning, conditions should begin to clear from west to
east as surface wind become more northwesterly. As the cold front is
quickly replaced by a mid-level ridge, the SPG will tighten leading
to some marginally breezy conditions from the James River eastwards
with gusts up to 25 mph possible by the afternoon hours. Otherwise,
increasing warm air advection (WAA) and deep mixing with help
temperatures increase slightly from the previous day with highs
expected to peak in the low to upper 80s by this afternoon. Lastly,
with increasing WAA advection expected overnight and light southerly
winds, expect our overnight temperatures to stay a touch above
normal with lows expected to be in the low to mid 60s.

The Long Term (Wednesday-Sunday):

Heading into the extended period, hot and muggy conditions return by
Wednesday as an 850mb thermal ridge strengthens overhead. Increasing
warm air advection (WAA) along with a southerly to southwesterly
surface wind will help pull more warm and moist air into the region
area which will result in a notable increase in surface temperatures
from the previous day. The resulting highs will likely vary between
the upper 80s to 90s for the day. Shifting gears to our precipitation
chances, uncertainty still remains on our overall severe weather
risk. Looking aloft, deterministic guidance is split on how the
fast the mid-level will progress through the area with its
associated cold front.

On one hand, the GFS/NAM have the faster solution where convection
develops entirely over south-central and southeastern Minnesota by
21z where the nose of the upper-level jet resides. On the other
hand, the Euro/Canadian have the slower solution where the base of
wave sits across the center of our CWA with convection firing across
southwestern MN and our far eastern most column of counties.
While its still a bit too early to determine which solution will
prevail, the environment is still primed to promote moderate
destabilization with 2000-3000 J/kg of MLCAPE and 40-50 kts of
deep layer shear which are consistent among deterministic
guidance. This along with DCAPE values of 1000 J/kg and mid-
level lapse rates of 7 degree C/km will create an environment
favorable for large hail up to golf ball size and damaging
winds up to 65 mph with any developing discrete supercells
initially. As things grow more upscale into a line after 00z,
the primary threat will shift more towards damaging winds.

Looking into the latter parts of the week, a few scattered morning
showers will be possible by Thursday morning as mid-level
frontogenesis strengthens along the departing cold front. However,
only light accumulations are expected. Otherwise, lingering cold air
advection (CAA) aloft along with northerly to northwesterly surface
winds will keep our temperatures closer to our seasonal averages on
both Thursday and Friday as highs take a slight dip back into the
upper 70s to low 80s on both days as heights begin to rise with the
approaching upper-level ridging. Looking ahead, confidence continues
to increase in a multiple rounds of showers and storms from Friday
night into the day on Saturday as multiple mid-level waves lift out
of the Colorado Rockies into our area. While some uncertainty
remains on the severe weather risk and exact amounts, most ensemble
guidance shows low to medium confidence (30%-60%) in up to half an
inch of QPF for this time period. Lastly, increasing mid-level WAA
ahead of the cold front on Saturday along with southerly to
southeasterly surface winds will help temperatures warm back up into
the mid to upper 80s on both Saturday and Sunday.


&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1041 PM CDT Mon Jun 10 2024

Showers and isolated storms continue to push eastward across the
region and will continue for much of the overnight period. Overall
instability remains lacking though, so not expecting anything in the
way of severe weather. Should see dry conditions return by daybreak,
as winds become more southeasterly. Otherwise, look for direction to
turn northwesterly heading into the afternoon, with gusts between 15
to 20 MPH possible at times. Winds lessen near sunset, allowing
light and variable winds to prevail.

&&

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

&&

$$

DISCUSSION...Gumbs
AVIATION...SST