401
FXUS63 KFSD 050326
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1026 PM CDT Tue Jun 4 2024

.KEY MESSAGES...

- Scattered convection ahead of a progressive front will bring
  a limited risk for severe weather to portions of Minnesota and
  Iowa through 5pm.

- Gusty west northwest winds to 45 mph likely Wednesday
  afternoon behind a frontal boundary. Advisory conditions may
  be briefly met at times, but diminish quickly by the evening.

- Pattern shift the second half of this week will continue into
  next week. This pattern favors only modest precipitation
  chances (Saturday), but higher confidence for below normal
  temperatures and below normal precipitation across the 7 day
  period of time.

&&

.DISCUSSION...
Issued at 150 PM CDT Tue Jun 4 2024

THIS AFTERNOON:  A quick moving frontal boundary is approaching I-29
as 2pm approaches.  Large scale lift is beginning to increase, with
the development of scattered thunderstorms ahead of the front. A
narrow corridor of 1500-1800 J/KG MLCAPE persists ahead of the
front, allowing for some deeper growth as storms move into Minnesota
and Iowa.  Deep layer shear remains marginal AOA 15-20 knots as
storms develop, so the most likely outcome will be disorganized
multi-cell clusters capable of marginally severe hail and a few
isolated stronger wind gusts.

TONIGHT:  A deeper mid-lvl trough axis passes through the are
overnight, which should scour out any lingering cloud cover. Winds
will eventually turn westerly and remain light through the daybreak
hours of Wednesday.

WEDNESDAY:  Weak mid-lvl warm advection forms near daybreak ahead of
a secondary upper trough dipping into the Dakotas early in the day
on Wednesday.  Soundings show an increased layer of moisture AOA 700
mb, which may be capable of squeezing out virga, sprinkles or even a
few light rain showers along and north of I-90 from daybreak through
early afternoon.  A stronger cold front quickly drops southward in
the afternoon, reaching Highway 14 by early afternoon, I-90 by mid-
afternoon, and Highway 20 by late afternoon.  Deep mixing behind the
cold front will promote both a risk for diurnal based CU/sprinkles,
but also potential for gusts AOA 45 mph at times in the afternoon. A
wind advisory may be needed for a brief period of time in the
afternoon, but the overall strong wind risk is only a few
hours. Prefer to mix in some of the deeper mixing models for
peak wind gust guidance, which is an upwards deviation from the
NBM.

THURSDAY-FRIDAY: Mid-lvl heights begin to rise on Thursday. While
temperatures rise into the 70s, we`ll again be dealing with a fairly
breezy day.  Forecast soundings indicate mixing upwards of 750 mb,
which should result in fairly widespread afternoon gusts between 30
and 40 mph at times.  We may begin to see more cloud cover and
potentially an increase in rain chances late in the day on Friday.
Medium range guidance remains very split, with some guidance showing
the potential of a subtle wave moving through the ridge and weak
warm advection showers by late Friday into Saturday. GEFS ensemble
is the only ensemble really showing much potential of this taking
place, with nearly 40% probabilities of 0.10" of precipitation.
ECE/CME both suggest less than a 10% probability.  For now, see no
strong reason to deviate from the lower probabilities with the NBM
guidance.

SATURDAY-MONDAY: While uncertainty in the specifics remains fairly
high, the broad pattern trends continue to support increased
troughing over the Great Lakes and eastern third of the CONUS, with
general northwesterly flow throughout the Northern Plains during the
weekend and early next week. This pattern would favor dry, or nearly
dry, conditions, with temperatures running near to even slightly
below normal at times.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1025 PM CDT Tue Jun 4 2024

VFR conditions are expected for the TAF period. Clear skies and
light southwesterly winds begin the TAF period. Winds will turn
westerly and become windy during the morning hours. Winds will turn
a bit more to out of the northwest for the afternoon hours, with
gusts up to 30-40+ knots expected. The strongest winds look to
reside north of I-90. Light showers are possible across the area
during the morning and afternoon hours. As such, have added VCSH to
KHON and KFSDs TAF`s. The light showers may mix down slightly
stronger winds with them as well. Winds will wane into the evening
to end the TAF period.

&&

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

&&

$$

DISCUSSION...Dux
AVIATION...Meyers