569
FXUS63 KFSD 071730
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1230 PM CDT Tue May 7 2024

.KEY MESSAGES...

- A Wind Advisory has been issued for Gregory, Jerauld, Brule,
  Aurora, Charles Mix, and Douglas counties for gusts up to 45
  mph. The Advisory is in effect until 7 pm this evening.

- More widespread rain and isolated storm chances on Wednesday.
  Although severe weather is not expected, funnel clouds and
  locally heavy rain are possible - mainly along/east of I-29.

- Warmer and mostly dry conditions move in for the weekend and
  into early next week.

&&

.UPDATE...
Issued at 1021 AM CDT Tue May 7 2024

Westerly winds have already begun to strengthen this
morning along and west of the James River. A few gusts have already
touched 45 mph just west of the Missouri River. With mixing expected
to further strengthen through the rest of the morning hours along
with soundings showing no inversion at the top of the mixed layer,
expect strong wind gusts to persist through the afternoon hours. As
such, have issued a Wind Advisory for Gregory, Jerauld, Brule,
Aurora, Charles Mix, and Douglas counties for gusts up to 45 mph.
The Advisory is in effect through 7 pm this evening. Trends in the
strength of the wind will be monitored throughout the day today
which could result in expansions to the Advisory.

&&

.DISCUSSION...
Issued at 346 AM CDT Tue May 7 2024

CURRENTS: Showers and isolated storms are continuing to move out of
southwestern MN and northwestern IA early this morning. Winds are
already on the increase, with gusts through 3 AM CDT/08z around 20
to 35 mph. Seeing some breaks in the clouds across south central
into northwestern SD, but this is short lived as more cloud cover
pivots around the mid/upper low pressure. Temperatures are
holding steady in the 50s, but do expect areas in west of I-29
to fall into the mid/upper 40s by daybreak.

TODAY AND TONIGHT: Mid and upper level low continues to spin and
meander into western ND. We`ll be in westerly flow for part of the
day, with streams of vorticity advecting over the area. Expect
mostly cloudy skies today with the low off to our northwest.
Vorticity as well as some very weak instability (less than 100 J/kg)
could lead to isolated showers through the day; however, soundings
show that we may struggle a bit with saturation in this unstable
layer, so showers remain isolated and limited mention to sprinkles.
Near average temperatures with highs in the 60s to lower 70s. Winds
remain breezy today (out of the southwest by the afternoon) with
gusts 30 to 40 mph and sustained winds around 10-20 mph thanks to
strong flow aloft and a compressed surface pressure gradient. Could
see some isolated higher gusts in south central SD where mixing may
be more efficient later this afternoon, and stronger gusts may also
mix down with showers. Will keep an eye on the potential for a small
Wind Advisory in south central SD, especially if some of the these
more mixy soundings end up being reality. Winds and showers taper
off after sunset as we lose mixing. Lows tonight fall into the 40s.

WEDNESDAY: Mid and upper low wobbles back to the east Wednesday,
centering itself over our forecast area. This brings back more
widespread shower chances with isolated thunderstorms. Instability
is still fairly weak around 1000 J/kg, although some of the
more aggressive models (like the RAP) do have instability around
1500 J/kg. Severe weather looks unlikely - that said, cannot
entirely rule out some funnels and/or landspouts with showers
and isolated storms with the mid/upper low overhead. Mid level
lapse rates at or above 7 deg C/km coincident with the instability
and vorticity advection are somewhat favorable for this potential
along and east of I-29 during the late morning through the
afternoon hours. Folks should keep an eye on the forecast. Could
also see some brief and localized heavy rainfall with slower
shower/storm motion, with some rainfall totals east of I-29
possibly approaching an inch. Otherwise, less breezy with
north/northeast winds. Widespread showers/isolated storms and
cloud cover keeps temperatures a bit cooler, in the 60s. Lows
fall into the 40s once again.

THURSDAY INTO EARLY NEXT WEEK: Lingering showers into the day on
Thursday as the mid/upper low finally moves off to the south. Near
normal temps expected. A mid level wave and upper jet swing through
eastern ND and MN on Friday, which could bring back showers and
isolated storms to areas east of I-29 into the day Saturday. Ridging
begins to build across the Rockies by the latter half of the weekend,
allowing us to warm to above average temperatures with mostly dry
conditions into the early part of next week as the ridge axis slides
eastward.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1230 PM CDT Tue May 7 2024

VFR conditions are expected for the TAF period. Surface low pressure
continues to spin over the North Dakota and South Dakota border this
afternoon. Gusty west/southwest flow will persist through the
afternoon hours with gusts up to 30-40 knots, strongest along and
west of the James River. A CU field has developed this afternoon,
based around 5,000 ft but should lift to around 8,000 ft as mixing
further increases. Sprinkles to very light showers are possible
beneath the CU but confidence is only high enough to include in
KHON`s TAF at this time.

The diurnally driven CU field will dissipate as mixing ceases this
evening. Winds will also wane to light and variable during the
overnight hours. Variable winds will finish out the TAF period as
another surface low pressure system pushes into northwest Iowa.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 7 PM CDT this evening for SDZ050-052-057-
     058-063-064.
MN...None.
IA...None.
NE...None.

&&

$$

UPDATE...Meyers
DISCUSSION...SG
AVIATION...Meyers