000
FXUS63 KFSD 092250
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
550 PM CDT Tue Apr 9 2024

.KEY MESSAGES...

-  The warming trend will continue into Wednesday. Low risks
   for light rain move in Wednesday night into Thursday, with
   probabilities for more than 0.10" less than 20%.

-  The combination of warm, mostly dry, and breezy conditions
   will lead to elevated fire weather conditions Wednesday and
   Thursday.

-  Uncertainty remains in the extended portions of the forecast,
   though ensembles are starting to converge now showing a 10 to
   20 degree spread in potential high temperatures Friday
   through Sunday.

&&

.DISCUSSION...
Issued at 259 PM CDT Tue Apr 9 2024

Early afternoon satellite imagery shows plenty of cumulus
development as air parcels have reached their convective
temperatures, with possibly some sprinkles developing throughout the
rest of the afternoon hours. Despite almost 200 J/kg of CAPE,
moisture is rather lacking in the lower levels, so rather than
actual rain showers expect scattered sprinkles as most of the rain
looks to evaporate before reaching the ground. Other than the breezy
westerly winds gusting into the 20s and lower 30s across the region,
today has been a rather pleasant April day with temperatures in the
upper 50s to mid 60s.

Will be watching a weak mid-level trough and associated frontal
boundary move towards the area overnight, with the front beginning to
move into our northern fringes prior to sunrise. Despite the frontal
passage, Wednesday is poised to be even warmer than today was, with
850mb temperatures reaching up into the 4-7 deg C range. While this
will require breezy winds to mix these temperatures down, afternoon
highs look to peak in the lower to upper 60s, though lower 70s can`t
be ruled out along and east of I-29. Winds will be strengthening
throughout the day, with the surface pressure gradient (SPG) highest
in the afternoon hours which will produce the strongest winds. Areas
west of I-29 will see west-northwesterly wind gusts of 25 to 35 mph,
whereas areas along and east of I-29 will be in the 15 to 25 mph
range. Cold air lags behind the front, but will be dragged into the
area by the late afternoon hours for areas in central South Dakota,
clearing the rest of our counties off to the east by Thursday
morning.

As for rain chances, with precipitable water values near half an
inch and dry low/mid levels, not expecting much in the way of
accumulations. Still, as the mid-level wave begins to move into the
area throughout the early afternoon hours, scattered light rain
showers are expected to develop with guidance suggesting we could
see these continue into Thursday morning before the main wave moves
through ending our precipitation chances. Rainfall amounts continue
to look rather unimpressive, with global ensembles keeping chances
for a tenth of an inch below 20%, which agrees well with the 24 hour
probability matched mean from the HREF showing amounts below a tenth
of an inch. With a surface ridge building in from the west, the SPG
again increases overnight into Thursday, with gusts of 30 to 40 mph
throughout the day. While this will ultimately depend on how
rainfall chances end up panning out, relative humidity values
currently look to drop down into the 20s and 30s. While we have
received some rainfall recently, not sure it is enough to offset how
dry we have been...something to closely monitor as very high fire
conditions are possible.

Friday into the weekend will see a strong ridge build across the
western CONUS, with the surface high pressure sliding down towards
the southeastern CONUS. Deterministic and ensemble guidance continues
to show very warm temperatures build into the region by Saturday and
Sunday, possibly up into the lower 80s. The GEPS remains the
warmest, giving the entire area 80-90% chances for 80+ degree
temperatures, while the GEFS is much lower peaking into the 70%
chance range along the MO River Valley. Other ensembles have much
lower chance, some not giving any probabilities for 80 degree
temperatures. However, with the ensemble situational awareness
tables continuing to show 850mb temperatures in the 90-97.5th
percentiles of climatology, indicating very warm air with respect to
the time of the year, it`s difficult to entirely discount the NBM
and its warm temperatures at this time. Lastly, record max
temperatures are in the lower 90s for the weekend, which does give
weight to temperatures in the lower 80s given anomalously warm 850mb
temperatures.

After the ridge breaks down early next week, a period of more active
weather looks likely into the middle of the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 545 PM CDT Tue Apr 9 2024

VFR conditions are expected through the TAF period. Light
westerly winds overnight will increase out of the northwest by
Wednesday afternoon, with occasional gusts around 20 to 25 kts.
May see very light rain or sprinkles develop in locations mainly
north of Interstate 90 on Wednesday afternoon, with little
impact to aviation concerns.

&&

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

&&

$$

DISCUSSION...APT
AVIATION...JM