863
FXUS63 KFSD 031045
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
545 AM CDT Mon Jun 3 2024

.KEY MESSAGES...

- May see a few strong to severe storms Tuesday afternoon, but
  will be dependent on recovery from scattered morning storms
  and timing of a cold front pushing through the region. Favored
  area for an isolated (Level 1 of 5) severe threat is along
  and east of the MN/IA Highway 60 corridor.

- Dry with windy periods Wednesday-Thursday. Lighter winds are
  expected Friday-Sunday with seasonable temperatures.

- Low (20-30%) chances for showers or a few thunderstorms
  Friday night. Neither severe weather nor heavy rain are
  expected.

&&

.DISCUSSION...
Issued at 349 AM CDT Mon Jun 3 2024

TODAY: Ongoing showers/storms across our eastern forecast area early
this morning are expected to exit by mid-morning. The remainder of
the day should see more prevalent sunshine and light winds. Will be
on the warmer side with highs in the lower-mid 80s, and still humid
across at least southeast areas where lighter winds will be unable
to scour out the dew points in the lower-mid 60s.

TONIGHT-TUESDAY: Will see increasing southeast to south winds this
evening as low level jet begins to increase across central portions
of Nebraska and the Dakotas. This will pull the more humid low level
air back across much of the forecast area tonight, while broad warm
advection and height falls ahead of an approaching trough support
development of elevated showers/storms after midnight tonight,
mainly near/west of I-29. Models indicate potential for pockets of
1000J/kg MUCAPE and shallow layers of steeper mid-level lapse rates,
but weak shear should limit potential for organized severe storms.
Still isolated small hail cannot be ruled out from some stronger
pulsy cores.

Early morning activity looks to maintain at least scattered coverage
sliding east into MN/IA, along and ahead of a cold front which will
be pushing east across the Upper Midwest. This should limit daytime
heating, with highs mainly in the 70s, perhaps nudging up toward 80F
in our far east before the rain moves in. However, deeper low level
moisture continues to build northward ahead of the front, leading to
moderate MUCAPE values of 1000-1500 J/kg. 700-500mb lapse rates are
less than impressive, but a shallower layer below 600mb shows where
the greater instability lies, with lapse rates closer to 8.5-9 C/km.
Although deep layer shear ahead of the cold front is on the weaker
side where instability is greatest, could see a few stronger cores
produce hail up to half dollar size or isolated gusts to 60 mph
during the afternoon-early evening before storms push east of our
forecast area. Given current timing of the cold front, the area
outlooked as a Level 1 of 5 (Marginal) risk by SPC near/east of the
MN/IA Highway 60 corridor looks reasonable.

TUESDAY NIGHT-THURSDAY: Expect most storm activity to be east of the
area by 05/00Z, with a drier northwest flow dominating the middle
portion of the week. Subtle wave slides southeast across the Dakotas
and Minnesota Wednesday afternoon. Limited moisture should preclude
any rain chances, but it may aid in mixing some stronger wind to the
surface, with a potential for gusts 35-40 mph. NAM/GFS forecast
soundings show 40+kt winds atop the deep mixed layer Wednesday
afternoon, so cannot rule out some areas flirting with advisory
criteria. Will have to monitor trends in later forecasts. Gradient
relaxes a bit by Thursday, but should still be breezy with mixing
during the afternoon.

FRIDAY-SUNDAY: While models diverge on the handling of the strong
upper low over the Great Lakes late in this forecast period, we look
to remain in generally northwest flow across the northern Plains
through the upcoming weekend. This should provide for mostly dry
conditions with seasonable temperatures, though seeing moderate
consensus in timing a subtle wave across the area Friday night which
could produce spotty showers or thunderstorms. Instability is pretty
sparse, though, so severe weather is not expected. A broad surface
high across the Dakotas/Minnesota should also provide for lighter
winds through the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 545 AM CDT Mon Jun 3 2024

Lingering light showers/isolated thunder in northwest Iowa at
12Z should exit east of KMWM-KSPW-KSLB by 14Z-15Z. Also seeing
patchy fog in portions of east central SD along the Highway 14
corridor where skies have already cleared, but this likewise
should dissipate within the first hour or two of this TAF
period.

Remainder of today will feature light/variable winds, which will
become southeast to south by this evening. Increasing low level
jet west of I-29 will result in occasional overnight gusts up to
25kt, with low level wind shear possible. However, not confident
enough to introduce LLWS just yet. Also anticipate development
of high-based SHRA/TSRA during the latter part of this period,
again mainly near and west of I-29 through 04/12Z, though this
activity will slide eastward into MN/IA after 12Z Tuesday.

&&

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

&&

$$

DISCUSSION...JH
AVIATION...JH