667
FXUS63 KFSD 152341
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
641 PM CDT Mon Jul 15 2024

.KEY MESSAGES...

- A small threat for isolated severe thunderstorms on Tuesday,
  with the better chances in south central SD.

- Temperatures will be about 5-10 degrees below normal through the
  weekend.

- Next better chance for showers and thunderstorms after Tuesday will
  be Friday and Friday night.

&&

.DISCUSSION...
Issued at 241 PM CDT Mon Jul 15 2024

Currently looking like a very small window for any severe
convection. Areas near and south of a Sioux City to Storm Lake line
could see a quick updraft develop from about 5-7 pm. Model soundings
are suggesting that capping may be tough to overcome, but if it can
be about 2500 J/kg CAPE and deep shear of 30-40 knots would support
the potential for large hail and damaging winds, with the wind
threat potentially more concerning. A few hi res models are hinting
that an isolated updraft could develop in southwest MN during this
time along the cold front but model soundings suggest that capping
will hold. The freezing level is at about 13000 feet AGL which can
limit the hail potential but there is a decent dry sub cloud layer
at and below about 700 mb which may support some stronger straight
line winds and microburst potential.

The right entrance region and a weak wave will swing through on
Tuesday which will bring another chance for showers and
thunderstorms. Current expectations are for upwards of 1000 J/kg
CAPE and about 30 knots of deep shear, with the better chances for
this environment in south central SD. So the overall threat for
severe storms is low, but an isolated severe storm around Gregory
county will be possible. Otherwise temperatures and humidity will be
much lower with highs from the upper 70s to lower 80s and dew points
more into the upper 50s to mid 60s.

Tuesday night into Thursday cooler air spills into the area as weak
northerly flow aloft develops. This is in response to a slow moving
trough of low pressure across the Great Lakes and upper level
ridging developing in the southwest United States. This should bring
mostly dry conditions with lows in the 50s and highs in the 70s.

The next piece of energy of potential interest will come on Friday.
With the potential strength of the warm advection and with weak to
moderate instability suspect at least isolated severe storms will be
possible.

Once this system moves through models diverge a bit, but the overall
trend is to take this energy and slowly drift it southward. This
should take the better chances for showers and thunderstorms with
it, but will also reinforce the cooler air leaving temperatures 5-
120 degrees below normal. Saturday and Sunday will see isolated
chances but confidence is low right now.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 640 PM CDT Mon Jul 15 2024

VFR conditions expected into the overnight period, with light and
variable winds into the morning hours. Will see a few chances for
scattered showers and thunderstorms throughout the day on Tuesday,
especially for areas west of I-29 from roughly 12-18Z. Last round of
showers/storms is expected after 20Z, moving from north to south
into the early evening hours. 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...08
AVIATION...APT