708
FXUS63 KFSD 170342
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1042 PM CDT Tue Jul 16 2024

.KEY MESSAGES...

- Patchy fog is expected to develop overnight, with visibilities
  below 1 mile possible. If you encounter fog, slow down and
  drive to conditions.

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

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

&&

.DISCUSSION...
Issued at 230 PM CDT Tue Jul 16 2024

After a small window late this afternoon where a few showers and
thunderstorms in south central SD will be possible, drier air will
settle in as high pressure at the surface builds. There will
also be a threat for very isolated showers, possibly a rumble of
thunder, in parts of southwest MN this evening, but severe
weather is not expected. This will bring quiet weather tonight
with dew points remaining in the lower 60s or dropping a bit. By
morning, lows should fall into the upper 50s in most locations.

Wednesday may start with some patchy fog, but will turn into a
mostly sunny and mild day as dew points further fall into the mid
50s. Highs will top out mostly in the 70s with winds remaining on
the lighter side as surface high pressure is stubborn to exit the
area.

Wednesday night into Thursday morning will see cool high pressure in
place east of I-29 which will support some very cool morning lows in
the lower 50s. Central SD should see some southerly flow so lows
will be closer to 55 to 60.

A wave will top the ridge in Montana Thursday night and settle south
on Friday. This will bring stronger warm advection in the low to mid
levels with an increased chance for showers and thunderstorms.
Models soundings indicate about 1500 J/kg CAPE with minor deep shear
so locally heavy rain and isolated severe storms should be the main
threat. The better chances appear to be Friday night into Saturday.
Temperatures Thursday and Friday look to remain below normal.

Once this wave dips south, models are becoming more agreeable that
an upper level low will dawdle around the Central Plains into early
next week which would keep some cloud cover in place, periodic
chances for showers and storms (especially diurnally driven) and
continued below normal temperatures. The main threats during this
time would be very local heavy rain with a good chance for very slow
storm motion if something develops.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1036 PM CDT Tue Jul 16 2024

With the latest round of showers exiting off to our east, the recent
moisture with a strengthening surface inversion introduces chances
for patchy fog across the region. Latest HREF data suggests the best
chances (scattered 30-40%) for visibilities below a mile are
expected for areas west of I-29, with probabilities along and east
of I-29 lagging behind some of the latest models which show patchy
visibilities of 3-5 miles. Winds will remain light and variable into
the morning hours, becoming north-northeasterly throughout the day
on Wednesday. Mostly dry conditions expected, though an isolated
sprinkle can`t be ruled out.

&&

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

&&

$$

DISCUSSION...08
AVIATION...APT