235 
FXUS63 KFSD 230332
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1032 PM CDT Thu Apr 22 2021

.SHORT TERM...(This Evening through Friday)
Issued at 155 PM CDT Thu Apr 22 2021

Mostly sunny skies become more cloud-covered this afternoon, as a 
well-defined shortwave trough moves eastward across the region this 
evening and overnight. Moisture in the atmosphere is lacking, as 
demonstrated by low relative humidities in the 20 to 30 percent 
range early this afternoon. Although green-up is well underway, 
grassland fire danger will be elevated through sunset due to a 
combination of dry air and wind gusts to around 30 mph.

As rain showers enter the area this evening, dry air in the lowest 
mile of the atmosphere serves to evaporate much of the precipitation 
that falls from the elevated cloud layer. Showers are possible 
throughout the overnight hours, but totals by sunrise Friday are 
generally less than a tenth of an inch.

Temperatures Friday look largely similar to Thursday's given the 
mild air mass upstream; however, locations near Sioux City Iowa 
could be a solid 5 degrees warmer given light south and southwesterly
surface flow lingers here until mid-afternoon.

.LONG TERM...(Friday Night through Thursday)
Issued at 155 PM CDT Thu Apr 22 2021

A continental polar air mass pushes southward on Saturday, bringing 
breezy north winds and an appreciable cooldown into the upper 40s to 
mid 50s. Diurnal cooling Saturday night into Sunday morning allows 
temperatures to drop to near freezing as a vorticity maximum causes 
lift across the northern Plains. Another round of rain showers is 
likely Sunday morning into the daytime. It's worth noting that 
sunrise temperatures along the buffalo ridge could be cold enough to 
support rain falling as snow, with a dusting of accumulation: Winter 
is having a hard time letting go.

Upper-level ridging over the central CONUS Sunday through Tuesday
makes this a much warmer timeframe. Temperatures warm into the 
70s for south central South Dakota on Sunday, but lingering cloud 
cover and rain showers keep southwest Minnesota in the 50s. Monday
is the mild day area-wide, with 70s (north of I-90) to low 80s 
(south of I- 90). On Tuesday, have added some slight chances for 
thunderstorms across northwest Iowa. The upper-level flow is 
southwesterly by this point, and decent moisture advection ahead 
of an incoming longwave trough could prompt convection.

Rain chances linger on Wednesday, and then by the end of next 
week the region will sit under a building ridge leading to cooler 
but drier weather.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1030 PM CDT Thu Apr 22 2021

Light showers will continue to push across the area tonight with 
no significant visibility obstruction expected. Could be a brief 
period of MVFR/IFR ceilings east of Interstate 29 on Friday 
morning before scattering out by afternoon. A frontal boundary 
will slide through the area on Friday with southerly winds 
transitioning to northerly behind the front.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...VandenBoogart
LONG TERM...VandenBoogart
AVIATION...JM