Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 201141
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
541 AM CST Tue Feb 20 2018

.SHORT TERM...(Today and Tonight)
Issued at 302 AM CST Tue Feb 20 2018

Strong wave moving through early this morning will finally take the
moisture and lift with it to the east. For the most part the
precipitation has all changed over to snow, but there were reports
of sleet and a little lightning in southeast SD and northwest IA
from about 5z through 8z. While the convergence in the mid levels
exits pretty early this morning, the low levels remain fairly
dendritic so may see some flurries through early afternoon.
Accumulations after about 15z this morning will be minimal to none.
Cold air remains buried in the region today and with fresh snow
cover not helping any heating potential. Highs will generally be in
the teens and with a northwest wind of 15 to 25 mph wind chill
values through the day will generally be about 5 below to 10 below
zero.

Cold high pressure settles into the area overnight so expecting some
pretty cold lows on Wednesday morning. With winds expected to be
about 5 to 10 mph through the night wind chill values may drop below
20 below zero at times. Will not issue any wind chill headlines
right now but wait until confidence increases and current headlines
are resolved. Low temperatures should be about 5 below to 15 below
zero.

.LONG TERM...(Wednesday through Monday)
Issued at 302 AM CST Tue Feb 20 2018

Wednesday will be a recovery day from the cold high pressure
shifting southeast, but not expecting a whole lot of warming. Even
with abundant sunshine highs will only be from about 15 to 25
degrees.

On Wednesday night the next system of interest will approach from the
west. This will bring broad and unfocused warm air advection to the
region so not anticipating any precipitation before sunrise
Thursday. The exception might be parts of northwest IA where there
are hints of enough low level saturation to allow a little light
snow to fall. Will only have a small chance for this until
confidence increases in one direction or the other.

Thursday into Thursday night will be the next best chance for
measurable snowfall, especially during the afternoon and evening.
Went ahead and increased the chance for snow as well as snow amounts
a bit with the extended period of warm advection and favorable
temperatures for snowfall. By late Thursday afternoon and evening
some warmer air aloft spreads north and might again support a little
freezing drizzle across parts of northwest IA, but for now the set
up does not look as impressive as yesterday. Therefore will just
have a chance for freezing drizzle over this time from about Sioux
City to Storm Lake. Because warm advection occurs over about 12
hours snowfall amounts may be in the moderate range.

As this system exits the air behind is not too cold so highs Friday
should be in the 20s. Late Friday night into Saturday morning
another faster moving system may bring another shot of light snow,
so not expected to be a big impact.

Temperatures into the weekend should be mild with highs Saturday,
Sunday and Monday in the 30s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 540 AM CST Tue Feb 20 2018

Light snow will continue at least in the vicinity of all TAF sites
during the early part of the period. MVFR ceilings are expected
persist today with improvement eventually coming Tuesday
afternoon. Gusty northwesterly winds are also expected today.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until noon CST today for SDZ038>040-050-
     052>069.

MN...Winter Weather Advisory until noon CST today for MNZ071-072-080-
     081-089-090-097-098.

IA...Winter Weather Advisory until noon CST today for IAZ001.

NE...None.
&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...Ferguson



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