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000
FXUS63 KFSD 211926
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
226 PM CDT Sun Apr 21 2024

.KEY MESSAGES...

- Periods of gusty winds Monday and again Tuesday may result in
  areas of increased fire danger where vegetation has not yet
  greened-up sufficiently.

- Scattered showers or sprinkles are possible Monday afternoon
  and again Tuesday afternoon, mainly near and east of I-29. Any
  rain amounts should remain minimal.

- Frost will be possible Wednesday morning with widespread
  low temperatures in the 30s.

- Next chance of widespread meaningful precipitation arrives
  later Thursday into Friday and again later in the weekend.
  There is a small chance of a few strong to severe storms
  during this period as well.

&&

.DISCUSSION...
Issued at 222 PM CDT Sun Apr 21 2024

Rest of Today: Clear skies continue through sunset with
west/northwest gradually sinking back toward southwest this evening.
Relative humidity values have fallen near/into critical fire weather
values but winds have largely remained shy, and combined with
greening vegetation, will continue to forgo any needed headlines.

Tonight: Jet streak begins to nose out of the northern Rockies as
mid level wave slides north of the International border. This will
result in a tightening SPG through the second half of the overnight
as winds take on a more southerly direction.

Monday: Tandem cold front to previously mentioned midlevel wave
pushes into center SD by the morning with gusty south/southwesterly
winds ahead of it, strongest across NW IA/SW MN. Not out of the
question to have a few gusts nearing/exceeding 45 mph but at this
point coverage and duration appear borderline enough to punt on a
Wind Advisory. As front passes, winds turn back out of the northwest
and gust closer to the 25-35 mph range.

Relative humidity values behind the front again fall near or into
critical fire weather values but looking through area webcams,
current greenness percentage appears high enough to prevent the need
for a fire weather headline. With this said, any areas with a more
susceptible vegetation dryness profile should be monitored for fire
weather starts with the RFTI indicating a max category of Elevated
to Near Critical (again, dependent on local fuels).

Beyond the breezy winds, just enough weak instability to allow for
perhaps a few light showers sprinkles, mainly east of I-29. Forecast
sounding suggest this activity should be relatively high based and
thus anything reaching the surface should stay light (few hundredths
or less, if anything).

Tuesday and Wednesday: Reinforcing shot of CAA pushes highs back
toward the mid 50s to mid 60s for Tuesday with gusty northwesterly
winds Tuesday. Could also see some spotty showers/sprinkles pivot
thru near/east of I-29 during the afternoon with some weak uncapped
instability noted in the soundings. Wednesday morning will be
another period to watch for frost as surface high settles to our
east. Ensemble probabilities of low temperatures below 40 degrees is
high (greater than 70%) and with light winds, sensitive vegetation
will again be at risk. Portions of SW MN/NW IA look to stand the
best chance of approaching the freezing mark, closest to the surface
high.

Thursday through Sunday: Mid/upper level troughing establishes
across the Intermountain West by the second half of the week as
southerly return flow begins to usher in moderating temperatures and
rising dewpoints. First wave ejects later Thursday into Friday and
will bring our next chance of meaningful precipitation. A second
wave arrives for Sunday with renewed thunderstorm chances. Both CIPS
analogs and machine learning probabilities would suggest some
potential for severe weather during this period with higher chances
to our south.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1141 AM CDT Sun Apr 21 2024

Clear skies will prevail through the daytime hours today with
northwest to westerly winds taking on a more westerly to
southwesterly component this evening. Winds will eventually
turn southerly overnight and then hedge toward southwesterly,
becoming breezy to gusty by the daybreak hours Monday. Any
periods of relatively lighter surface winds through the second
half of the overnight hours may carry some risk of LLWS with a
strengthening low level wind profile. Isolated very light
showers will also become possible late in the period.

&&

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

&&

$$

DISCUSSION...Kalin
AVIATION...Kalin