235
FXUS63 KFSD 081941
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
241 PM CDT Wed May 8 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms remain likely this
  afternoon and evening, transitioning to a more showery threat
  after 10 pm. Isolated storms could produce hail to the size
  of half dollars as well as wind gusts to 50 mph. Some threat
  for localized heavy rainfall exists, with the better chance in
  parts of northwest IA, although confidence is low.

- Warmer and mainly dry conditions move in for the weekend.
  Continued warm with renewed rain chances by mid week.

&&

.DISCUSSION...
Issued at 239 PM CDT Wed May 8 2024

Showers and thunderstorms should increase in coverage across parts
of northwest IA and southwest MN through the afternoon as well as
near highway 14. A small axis of instability is expected this
afternoon in this area. Overall instability not that high, but with
the freezing level around 6-7 kft it will be pretty easy to get some
smaller hail. Still looks like an environment supportive of hail up
to half dollar sized with only weak shear expected. One other thing
to watch will be the potential for funnels and landspouts. Steep low
level lapse rates and lighter winds near a surface boundary may
support this type of activity. With only marginal instability and
weak shear any activity like this should be short lived. While some
stronger winds gusts will be possible the HRRR and HREF both
indicating gusts should generally be 50 mph or lower.

The upper level low pressure shears out and sags south tonight into
Thursday. Scattered showers will remain possible during this time,
but instability is quite a bit less so even lightning will likely
diminish quite a bit after about 10 pm. Lows will be seasonally mild
in the mid 40s.

While the main synoptic forcing settles south, model soundings do
show some weak instability near the top of the mixed layer on
Thursday which may support some isolated showery activity.
Temperatures will also be a touch cooler as winds turn northerly and
some diurnally driven cloud cover is expected to develop. Highs
should still be in the 60s.

Friday and Saturday will be dry and mild as northwest flow aloft
weakens and westerly flow in the low levels is in place. By Sunday a
weak wave in this flow could bring some isolated activity but for
now this looks to be low impact. Highs should gradually warm from
the lower 70s Friday to the lower 80s by Sunday.

West to northwest flow aloft is expected Monday and Tuesday which
should lead to a couple of warm days. While this pattern will not be
a wet one, some spotty shower and thunderstorm activity will be
possible. The most agreement appears to be Monday night into Tuesday
morning.

Wednesday into Thursday the models are indicating a strong upper
level jet max diving into the Northern Rockies which should turn
upper level flow more southwesterly and bring a better chance for
showers and thunderstorms.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1219 PM CDT Wed May 8 2024

Challenging forecast with isolated to scattered showers and
thunderstorms expected. For now the lower chances appear to be
near the Missouri River this afternoon and evening with the
better chances in parts of northwest IA and southwest MN then
north of I-90 in SD. A few of the storms could contain hail,
strong winds and lightning as well as an isolated funnel cloud
or landspout. The better chance for hail will be around
northwest IA and southwest MN with the better chance for funnels
in SD. Overall outside of the showers and storms VFR conditions
are expected, with an increasing chance for MVFR ceilings south
of I-90 on Thursday morning.

&&

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

&&

$$

DISCUSSION...08
AVIATION...08