809
FXUS63 KFSD 041930
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
230 PM CDT Sat May 4 2024

.KEY MESSAGES...

- Conditions will continue to trend warmer into the early parts
  of the week with highs returning to upper 60s and low 70s by
  Sunday.

- Winds may near and/or exceed advisory levels Monday morning
  and 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 Missouri River and
  Highway 20 corridor.

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

&&

.DISCUSSION...
Issued at 228 PM CDT Sat May 4 2024

REST OF THE AFTERNOON/TONIGHT: A warm and quiet day continues.
Taking a look at satellite imagery across the area, mostly clear
conditions this morning have given way to developing cumulus field
this afternoon mostly due to some elevated instability. Efficient
mixing along with a tightening SPG has led breezy northwesterly
winds across portions of the area with a few sites reporting
sustained wind between 10-20 mph with gusts up to 30 mph this
afternoon. Expect the marginally breezy conditions to continue into
the evening hours before diminishing as a surface high approaches
from the northwest moves overhead. Otherwise, lingering cold air
advection (CAA) and northwesterly surface winds will lead to
temperatures slightly below our seasonal normal as highs approach
the upper 50s to low 60s for the day. By tonight, winds will likely
decouple becoming more variable after sunset as the surface high
moves overhead. Lastly, as temperatures decrease into the upper 30s
to low 40s overnight; a shrinking dewpoint depression could
potentially lead to a few patchy area of fog developing mostly over
portions of northwestern IA. Nonetheless, with high resolution
guidance only showing 10-20 percent confidence in any isn`t too
excited about those chances

SUNDAY: By Sunday, another warm and quiet day will be on tap as the
upper-level portion of the ridge moves overhead. Light and variable
winds in the morning will become breezy southeasterly winds by the
afternoon as the SPG tightens. Wind gusts between 20-30 mph will be
possible with the strongest winds expected west of the James River.
Looking aloft, some weak warm air advection (WAA) will mix into the
mid-levels by the afternoon hours helping our overall temperatures
slightly increase from the previous day. As a result, highs should
peak in the upper 60s to low 70s for the day. By Sunday night, our
attention pivots to the Rockies as an upper-level wave ejects into
the Central and Northern Plains leading to our next precipitation
chances from Monday onwards.

MONDAY: Upper level trough over the Rockies ejects northeastward
toward the Northern Plains Monday, causing showers and storms to
return to the forecast. While precipitation will be likely by mid-
morning in areas west of the James River, expect more widespread
chances to prevail during the afternoon and evening as the sfc low
pressure deepens over the western Dakotas. As alluded to in the
previous discussion, SPC`s Day 3 Outlook does include a Slight Risk
(Level 2 of 5) along the MO River Valley, with a Marginal Risk
(Level 1 of 5) encompassing those areas north up to the I-90
corridor. In regard to dynamics, latest guidance continues to show
MU/MLCAPE around 500 to 1000 J/kg depending on what model you look
at. That being said, ensembles remain less than excited, with both
the Euro/GFS only showing a 10-20% probability of seeing CAPE
greater than or equal to 1000 J/kg. Nonetheless, there will be a
fairly robust S/SE LLJ overhead, with winds ranging between 40 to 50
kts, resulting in highs in the 60s to lower 70s and dewpoints in the
mid 50s to lower 60s. CIPS analogs and CSU machine learning
probabilities also give us a 10-15% of severe weather, so don`t want
to completely rule things out just yet despite instability being on
the lower side.

In terms of accumulations, confidence continues to grow that we will
see another round of meaningful rainfall across much of the area, as
soundings reveal a tall and skinny profile. Latest QPF estimates
would suggest accumulations between half an inch to an inch,
especially in areas that see convection. In addition to the storm
potential on Monday, it will also be quite windy, with areas along
and west of I-29 approaching advisory level winds in the morning and
early afternoon hours as the SPG tightens overhead. Will continue to
monitor trends in the event that headlines are needed. Otherwise,
expect showers and storms to continue eastward overnight, allowing
largely quiet conditions to return by daybreak Tuesday.

TUESDAY THROUGH FRIDAY: Upper level low continues to spin and wobble
over the Northern Plains through mid-week, resulting in a persistent
wave train across our area. Thus, expect low-end PoPs (<40%) to
continue at least through Friday. Winds also look to be fairly
breezy each day, with gusts between 20 to 30 MPH possible each
afternoon. In regard to temperatures, will see highs to rise into
the 60s to lower 70s during this time, with overnight falling into
the 40s.

SATURDAY: Dry conditions look to return heading into the weekend as
the aforementioned upper level low pushes eastward, causing
northwesterly flow to set up overhead. Highs in the 60s will still
remain common.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1214 PM CDT Sat May 4 2024

Mostly VFR conditions with occasional MVFR ceilings are
expected for this TAF period. Taking a look at satellite
imagery, a cumulus field has developed across most of the area
in response to some elevated instability with parts of
northwestern IA dealing with lingering stratus from this
morning`s cold front. As the surface high continues to move into
the area this evening, expect conditions to begin to clear from
west to east. Otherwise, breezy northwesterly winds will
continue through the late afternoon before diminishing as the
surface high moves overhead tonight. Lastly, some high
resolution guidance has started to hint at some patchy fog
developing across northwestern IA overnight. However, confidence
is still low in occurrence so far.

&&

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

&&

$$

DISCUSSION...Gumbs/SST
AVIATION...Gumbs