Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 161113
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
513 AM CST Mon Jan 16 2017

.SHORT TERM...(Today and Tonight)
Issued at 341 AM CST Mon Jan 16 2017

Lead wave moving through the region early this morning with light
freezing rain presently occurring through the mid and lower Missouri
River Valley into portions of northwestern IA. Any moisture trying
to move northward is having a hard time with dry air firmly
entrenched across east central SD and southwestern MN. All hi res
models including the HRRR/RAP/NAMNest all indicating the current
area of precipitation across our south waning through the morning
hours as lead wave moves out of the area, with redevelopment not
occurring until late morning/early afternoon as the main upper level
low over Kansas slides into IA after 18z. Models still showing a
sharp gradient between areas receiving precipitation and those not,
which makes headlines a bit tricky. There is the possibility that if
the track of the system shifts even slightly farther to the east, a
couple of our counties presently along the western edge of the
Winter Weather Advisory may need to be dropped by the day shift.
Farther to the south and east confidence is higher with current
Winter Weather Advisories and Ice Storm Warning appropriate. As is
typical with these types of systems, precipitation type will be
tricky along the northern and western edges of the precipitation
shield, dependent on how quickly temperatures cool aloft. As
precipitation develops this afternoon and expands northward, there
may initially be just freezing drizzle toward the central/eastern
Interstate 90 corridor with saturation issues, then more of a
freezing rain/isolated sleet scenario as the atmosphere becomes more
saturated. Current models indicate thermal profiles aloft not
cooling sufficiently until the precipitation is close to ending, so
thinking that there will only be a brief period of snow on the back
edge of the system as it pulls away. With that thinking, any snow
accumulations should generally be around a half an inch or less.
Total ice accumulation through this evening continues to look near a
tenth of an inch from a Yankton to Canton to Worthington line, then
trending upward to around a quarter of an inch through the Sioux
City/Storm Lake/Spencer corridor. Temperatures will not be
especially cold today, ranging from the upper 20s northwest to lower
30s over through the MO River Valley into northwestern IA, and a few
locales may slip just above freezing for a brief period this
afternoon.

By this evening, mixed precipitation will change to snow before
ending in our southeast toward 06Z. Colder air then begins to filter
in behind the system with lows mainly teens and 20s.

.LONG TERM...(Tuesday through Sunday)
Issued at 341 AM CST Mon Jan 16 2017

A January thaw is on the way for for most of the region in the
medium and extended portions of the forecast. Tuesday will be the
coldest day of the week behind the departing upper trough. Low level
temperatures will surge above zero by the middle of the week as mid-
level heights build. Low 40s are possible Wednesday, with mid to
upper 40s on Thursday.

By the end of the week a bit more uncertainty enters the picture.
Shortwave energy ejecting into the mid-Mississippi River valley and
a secondary trough entering the Southern Plains will try to pull low
level moisture northward.  Should see a steady increase in stratus
or cloud cover.

Deterministic guidance swings the Southern Plains trough northeast
towards the area Friday night into Saturday. Temperatures look warm
as this system moves through so anticipating a very cold rain slowly
transitioning to a snow chance on Saturday.

No major cooldown for Sunday or early next week. Temperatures will
climb above normal both days with low end precipitation risks.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 505 AM CST Mon Jan 16 2017

MVFR/IFR ceilings will continue to spread over the area as a
winter storm takes shape across the region. Freezing rain or
freezing drizzle will develop through the morning, becoming most
widespread by afternoon. This precipitation is not expected to
affect the KHON TAF site however. Mixed precipitation may briefly
transition to snow by this evening, with only minor accumulations
expected. More significant will be ice accumulation which will
range from a light glaze at KFSD to around a quarter of an inch at
KSUX. Precipitation will taper off by 06Z tonight.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until midnight CST tonight for SDZ070-
     071.

     Winter Weather Advisory until midnight CST tonight for SDZ062-
     066>069.

MN...Winter Weather Advisory until midnight CST tonight for MNZ080-
     081-089-090-098.

IA...Winter Weather Advisory until midnight CST tonight for
     IAZ001>003-012-013-020.

     Ice Storm Warning until midnight CST tonight for IAZ014-021-022-
     031-032.

NE...Winter Weather Advisory until midnight CST tonight for NEZ013.

     Ice Storm Warning until midnight CST tonight for NEZ014.

&&

$$

SHORT TERM...JM
LONG TERM...Dux
AVIATION...JM



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