075
FXUS63 KFSD 072101
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
Issued by National Weather Service Aberdeen SD
401 PM CDT Mon Apr 7 2025

.KEY MESSAGES...

- One more relatively chilly night is expected tonight as clear
  skies combine with a dry air mass in place.

- Low pressure moving through the region late Tuesday through
  Wednesday will produce a 20 percent chance for rain showers.

- Temperatures rise above normal from the middle of the week
  through the upcoming weekend. 60s and 70s are expected for
  high temperatures.

- Rain chances return by the start of next week, though
  considerable uncertainty remains, keeping probabilities of
  precipitation low.

&&

.DISCUSSION...
Issued at 357 PM CDT Mon Apr 7 2025

The cooler than normal temperature trend observed today will spill
over into one more relatively cool night tonight before a warming
trend kicks off on Tuesday. The axis of a ridge of sfc high pressure
has been situated along the Dakotas/Minnesota today allowing a
chilly northerly flow to persist. Temperatures have struggled to get
to around 40 degrees this afternoon, despite the amply sunshine. The
aforementioned sfc high will drift eastward overnight into the
western Great Lakes by Tuesday morning. Our northerly flow becomes
more southeasterly overnight. Sfc dew point temperatures this
afternoon remain in the upper single digits to teens; an indication
of a very dry air mass in place. This will lead to a quick plummet
in temperatures after sunset tonight. A modest increase in mid lvl
warm advection takes hold overnight with 850mb temperatures rising
from the single digits below zero C to the single digits above zero
C. Some mid lvl cloudiness will accompany this thermal transition.

The modest warm advection pattern will continue through the day on
Tuesday. This should give our forecast area a nice boost in
temperatures with readings returning to the 50s to low 60s, which is
close to or slightly above normal for early April. A dry air mass
will remain in place with dew point temperatures in the 20s to
around 30 degrees. A tightening pressure gradient will lead to gusty
winds by the afternoon hours. We could see some gusts approach or
exceed 30 mph. Combining this with the warmer temps, relative
humidity values will drop to around 30 percent. This will lead to
high to very high grassland fire danger indices by the afternoon
hours creating a period of increased fire danger. An upper trough
approaches the Dakotas by the end of the day Tuesday. Associated sfc
low pressure will progged to track through the central Dakotas
overnight and into our forecast area closer to daybreak Wednesday. A
few scattered showers could begin to push into at least our western
zones by early Wednesday.

While a broad upper level ridge over the western CONUS dominates the
pattern in the extended period, an embedded shortwave will ride the
ridge down and over eastern South Dakota and western Minnesota
Wednesday into Thursday. This disturbance will bring some light rain
showers to the forecast area at that time, but only a few hundredths
are expected at most through both days. Overnight temperatures will
remain above freezing Wednesday night and the saturated layer aloft
will remain warm enough to support liquid droplet growth, so rain is
expected for any precipitation that falls.

The broad ridge mentioned previously will allow for warm and dry air
from the southwest CONUS to move into the forecast area. Highs will
reach their peak over the weekend, into the mid-70s. While this is
15-20 degrees above normal for mid-April, we will still fall well
short of record highs. Fire weather may become a concern depending
on just how high temperatures get, as minimum relative humidity and
winds sit just shy Red Flag thresholds Friday and Saturday. We will
continue to monitor conditions as the weekend draws nearer.

The next big system that has the potential to bring precipitation to
the area comes at the start of next week, currently Sunday into
Monday. While deterministic models keep the low track over North
Dakota/Southern Canada (and precipitation on the north side of the
low), there is still plenty of time for a variation in the track to
bring the low further south. An ensemble cluster analysis shows a 50-
60% chance for the development of a pattern in which the low will
track over the northern plains and bring chances for precipitation.
Even if the bulk of the precipitation stays to the north, the cold
front associated with the low may bring chances for showers or
storms as it passes through early in the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1248 PM CDT Mon Apr 7 2025

VFR conditions will continue to prevail through this next 24
hour forecast cycle. Sfc ridging will shift east of the area
this afternoon into this evening. Northeast breezes gusting
between 15-20 kts will be possible through mid afternoon before
winds relax by this evening and turn east to southeast tonight.

The gradient does begin to tighten by the end of this forecast
period. Light southeast winds will become gusty by 18Z Tuesday.
Mid to high level cloudiness will start to increase from west to
east by mid to late morning Tuesday.

&&

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

&&

$$

DISCUSSION...Vipond/BC
AVIATION...Vipond