398
FXUS63 KFSD 050903
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
403 AM CDT Sun May 5 2024

.KEY MESSAGES...

- Conditions will continue to trend warmer into the early part
  of the week with highs returning to upper 60s and low 70s for
  today and Monday.

- Winds may near advisory levels on Monday afternoon in areas
  along and west of I-29.

- A few strong to severe storms will be possible Monday
  afternoon and evening, with the greatest severe threat
  currently focused along and south of the lower Missouri River
  corridor into parts of northwestern IA.

- Periodic rain chances continue for much of the upcoming week,
  with highs in the 60s to lower 70s.

&&

.DISCUSSION...
Issued at 400 AM CDT Sun May 5 2024

Look for a pretty decent day ahead as surface high pressure
continues to exert its influence across the region. While the surface
ridge axis is located directly over our area this morning, it will
shift eastward during the day - into the Mississippi Valley by this
evening. Winds will be southerly in a weak warm air advection regime
on the backside of the high, and this will result in warmer
temperatures for today. With 850 mb temperatures of 7 to 10 degrees
across the area, look for highs in the upper 60s to lower 70s. A
deepening surface trough over eastern MT and WY will result in an
increasing surface pressure gradient (SPG) across our area, and this
will result in increasing winds by the afternoon. This will be most
pronounced west of Interstate 29 where the SPG is tighter and winds
at the top of the mixed layer are higher.

Tonight will see an increase in cloudiness - this as the
aforementioned surface trough continues to deepen and shift into
western SD, as an upper level low moves out of the Four Corners
region into eastern WY and CO overnight. As the SPG continues to
tighten over our area, winds will remain breezy during the night
time hours. With the breezy conditions and warm air advection, it
will be a mild night for this time of year with lows in the upper
40s to lower 50s.

The upper level low lifts through western NE and western SD/ND on
Monday and Monday night, while the surface low shifts northward
through the western Dakotas - pulling a warm front northward across
the region. With that, showers and thunderstorms will return to our
area for Monday and Monday night. There remains a potential for
strong to severe storms over the area on Monday afternoon/evening -
as outlined in the SPC Day 2 convective outlook (a Slight risk
[level 2 of 5] through the lower MO River Valley/northeast NE/parts
of northwest IA and a Marginal risk [level 1 of 5] north to around
the I-90 corridor). There are caveats however, with most models
indicating instability on the lower side - generally less than 1000
J/KG. At the same time, ensembles continue with low probabilities of
CAPE greater than 1000 J/KG - at only 10-20% over our area. In
addition, the latest machine learning and CIPS analog probabilities
are on the lower side for severe weather. There is however plenty of
0-6 bulk shear (around 40-50 kts) with strong winds through the low
to mid levels. So in summary, while this in not a slam dunk for
severe weather in our area, cannot rule out the potential for at
least a few stronger storms. Related, with the strong winds aloft,
it will be a windy day with sustained winds of 20-30 mph and gusts
of 40 to 45 mph. It will be a relatively warm day with highs in the
upper 60s to lower 70s. Any storms on Monday will exit our area very
early Tuesday morning. We could again see moderate to heavy rain
with the system, with latest ensembles indicating around a 70%
probability of receiving at least half an inch of rain.

For Tuesday through Friday, small to moderate (20-50%) rain chances
linger through the period. This as the aforementioned upper level low
rotates back to the northwest into the northern Rockies on Tuesday,
then back into the Northern Plains on Wednesday. It then only slowly
shifts to the east on Thursday and Friday, with perhaps a drying
trend toward next weekend. Highs through the period will be mainly
in the 60s with lows in the 40s. It looks to be a breezy each day.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1013 PM CDT Sat May 4 2024

CLear skies are anticipated into Sunday morning. Winds have
already fallen to near calm levels as midnight approaches. As
temperatures fall, there will be some potential for ground fog
to develop, perhaps moreso in valleys and river locations.

VFR conditions continue on Sunday with a low chance for
afternoon CU developing. Winds turn gusty by the afternoon with
potential for gusts approaching 30 knots along and west of the
James River Valley.

&&

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

&&

$$

DISCUSSION...JM
AVIATION...Dux