033 
FXUS63 KFSD 162322
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
622 PM CDT Mon Mar 16 2020

.SHORT TERM...(This Evening through Tuesday)
Issued at 335 PM CDT Mon Mar 16 2020

Mid afternoon satellite imagery shows widespread stratus across the 
region, associated with saturated lower levels as moisture remains 
trapped under surface high pressure. Short term models are doing a 
poor job handling stratus across southern ND and northern SD, so 
clearing for this evening may be slower than previously anticipated. 
Will need to monitor the progression of this stratus deck as it will 
affect overnight temperature trends. An upper trough axis progresses 
eastward through the region this evening and may bring some drizzle 
or light rain across parts of northwest IA and southwest MN as well, 
along with cooler air and weakening winds tonight.

The general forecast is quiet for Tuesday as surface high pressure 
propagates through the region. As warm air advection and ridging 
aloft develop, expect temperatures to be slightly warmer on Tuesday 
than Monday. Upper level clouds should begin to spread northward 
into the region late in the day, ahead of an approaching wave moving 
in Tuesday night.

.LONG TERM...(Tuesday Night through Monday)
Issued at 335 PM CDT Mon Mar 16 2020

An active weather pattern develops for the remainder of the work 
week with several rounds of precipitation. A warming trend develops 
through Wednesday before wintry weather returns to the region late 
in the week.

For Tuesday night into early Wednesday, warm air advection ahead of 
an approaching Colorado Low provides the focus for the first round 
of precipitation. Expect rain to prevail as the precipitation type 
Tuesday night through Wednesday night, as there is good agreement in 
low level and surface temperatures warming to above freezing. The 
best chance of rain and heaviest amounts Tuesday night are expected 
across northwest IA, northeast NE, and far southeast SD at up to a 
quarter inch, with potential for periods of light rain and/or 
perhaps light snow further north. At this point, the axis of the 
strongest lift and instability remains just south of the forecast 
area across eastern NE and central IA, but if that axis shifts 
north, it could bring thunder and higher rainfall amounts up to an 
inch to parts of northwest IA. Should see a drier period for much of 
the day Wednesday, but can't rule out periods of light rain or 
drizzle across the region on Wednesday night as well.

The second and more impactful period of widespread precipitation 
looks to start moving into the region from the south on Thursday 
morning, lingering through Thursday night and perhaps into Friday 
morning. This is associated with warm air advection and Fgen forcing 
with the aforementioned trough lifting through the Central Plains, 
reflected as a Colorado Low. Thermal profiles initially support rain 
as the dominant precipitation type, but it will likely vary across 
the region as a rain to wintry mix to snow transition occurs during 
the day Thursday. Expect temperatures to fall through the day 
Thursday as much colder air spreads in NW to SE. Latest guidance 
would suggest most sites will see snow by Thursday evening, with 
conditions starting to improve late Thursday night as snow ends.
 
Probabilistic data maintains low confidence in liquid equivalent 
amounts at any given location, ranging from a quarter inch to one 
inch. Given the p-type variability combined with high potential for 
localized variability in amounts given elevated instability coupled 
with strong Fgen forcing, it will be difficult to pinpoint snowfall 
totals for this event. An additional concern is much stronger, gusty 
winds with the cold air pushing into the region, causing reduced 
visibility due to blowing snow or heavy snowfall and wind chills 
likely dropping below zero Thursday night and Friday morning.

On Friday, winds will slowly weaken and provide some relief to wind 
chills, but colder air remains entrenched in the region through 
Saturday. This will yield daytime high temperatures remaining below 
the freezing mark.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 621 PM CDT Mon Mar 16 2020

MVFR ceilings will continue to press south with VFR conditions
settling in. Most locations north of I-90 will be VFR by 0z while
KSUX may seem them linger through about 3z. Mid level clouds will
increase late in the period.

&&

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

$$

SHORT TERM...BP
LONG TERM...BP
AVIATION...08