940
FXUS63 KFSD 280330
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1030 PM CDT Mon May 27 2024

.KEY MESSAGES...

- A 30% chance for scattered showers and thunderstorms exists
  overnight into Tuesday morning for areas along and east of a
  line from Huron, SD to Sioux Falls, SD to Storm Lake, IA.
  Severe weather is not expected at this time, with most areas
  remaining dry.

- Wednesday is expected to be dry. Multiple chances for showers
  and thunderstorms return Thursday through the weekend.

- Temperatures will be near average for this time of the year.
  Breezy conditions ease tonight. Wednesday afternoon through
  Thursday afternoon is also expected to be breezy.

&&

.DISCUSSION...
Issued at 222 PM CDT Mon May 27 2024

TODAY-TONIGHT: Water vapor imagery shows a well defined upper low
pressure system moving southeast across our area. This low is
responsible for the scattered showers and thunderstorms this
afternoon over southwestern Minnesota and northwestern Iowa. There
exists a Marginal (level 1 of 5) risk for severe thunderstorms over
this same area. Model guidance indicates a broad range of available
potential energy, with MUCAPE varying from 500 to around 1500
J/kg. A deep, dry subcloud layer will provide ample time for
evaporative cooling that could enhance downdraft strength into
the 60 mph range. Low freezing levels between 6000 and 7000 ft
AGL could support hail formation up to the size of a quarter.
This wave should be east of the region around midnight. Breezy
northwest winds will decrease this evening, becoming light and
variable overnight. Lows will be in the 40s.

TUESDAY: A second, weaker wave on the back side of the upper low
brings another round of scattered showers and thunderstorms for
early Tuesday morning. The latest guidance indicates most of the
showers forming in the early morning hours east of I-29. While
severe storms are not expected at this time, there is enough weak
instability available for a few rumbles of thunder. Showers clear
the area by early afternoon. Winds increase through the day,
reaching around 10-15 mph sustained, with gusts up to 25 mph. Winds
will initially be northerly, then shifting east through the evening
and overnight, eventually becoming southeasterly for Wednesday.
Highs for Tuesday will be a touch on the cool side thanks to the
northwesterly winds and CAA, in the mid 60s to mid 70s. Lows will
again be in the 40s.

WEDNESDAY: A weak ridge builds in for Wednesday. Clear skies and WAA
help us warm into the low to upper 70s. Meanwhile, a low
pressure trough is digging southward over the Rockies. As it
pushes east it will compact the SPG, bringing breezy conditions
for Wednesday afternoon. Winds will peak in the afternoon, with
the strongest winds west of the James River Valley. Sustained
around 15-20 mph with gusts 25-30 mph. The breezy winds progress
eastward overnight, spreading into southwestern Minnesota and
northwestern Iowa by Thursday morning.

THURSDAY AND BEYOND: By Thursday afternoon, a negatively tilted
upper trough ejects out over the northern Plains, bringing the
next chance for widespread showers and thunderstorms. Cloudy
skies and showers will limit highs into the low to mid 70s for
Thursday. Ensembles indicate a high (80- 90%) chance for
widespread quarter inch of rain, and a moderate chance (60-90%)
of a half an inch. At this time, the better dynamics for severe
weather stay to our south, but there is a lot of time for this
to change as the wave evolves. Several successive waves will
follow this one through the early part of next week, indicating
multiple chances for rain. However, confidence is low due to
high model uncertainty.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1026 PM CDT Mon May 27 2024

VFR throughout the period. A 30% chance for scattered showers and
thunderstorms exists overnight into Tuesday morning for areas along
and east of a line from Huron, SD to Sioux Falls, SD to Storm Lake,
IA. Have included tempo groups for both KHON and KFSD, though
impacts should remain minimal. Otherwise, expect light and variable
winds between westerly and northerly overnight, with semi-
breezy N/NW winds developing throughout the morning hours on
Tuesday.

&&

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

&&

$$

DISCUSSION...AJP
AVIATION...APT