Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 242323
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
523 PM CST Tue Jan 24 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 255 PM CST Tue Jan 24 2017

Focus remains on the winter storm bearing down on the region this
afternoon into Wednesday. The main precipitation focus will be along
an area of mid level frontogenesis around the 700 mb level. The
initial frontogenetic band is following a much slower progress than
previous model runs indicated, however still expect a major impact
to the evening rush hour commute for areas along and south of I-90,
and northwest into the Huron area. Models in strong agreement that
the frontogenetic band will lift northward into the I-90 corridor
late afternoon and evening, before diminishing as a second
frontogenetic band takes over across extreme southeast SD and
northwest Iowa late evening through the overnight hours tonight.
Moderate to heavy snowfall rates can be expected with the
frontogenetic band, with model soundings indicating some weak
elevated instability above the frontogenetic layer in extreme
southeast SD and northwest Iowa allowing some locally heavy snowfall
rates of 1+ inch per hour.

With the surface low center tracking eastward across the southern
plains this evening into Wednesday morning, snowfall will continue
in the deformation band on the back side of the low through daybreak
Wednesday. Snowfall intensity will decrease as the frontogenesis
likewise diminishes in the early morning, however the accumulating
snowfall will not be over. Light snow will persist through mid
morning Wednesday, then taper off from west to east Wednesday
afternoon. Heaviest snow amounts remain pegged for southeast SD in
the Missouri Valley and areas south of I-90, extending into
northwest Iowa, where the frontogenetic bands will have greatest
impact. Nine to 14 inches is possible in this area, with amounts
decreasing rapidly to the north of I-90. Only 2 to 5 inches expected
in the highway 14 corridor, including Brookings, Huron and Marshall.
Sioux Falls/Mitchell/Worthington/I-90 will be on the northern edge
of the heaviest snow band, with Yankton/Elk Point/Le Mars/Storm Lake
on the south edge. Would not be surprised to see the southern side
of Sioux Falls see higher amounts than the northern side of the city.

Winds will increase from the north northeast late evening and
tonight, turning northwest on Wednesday. Winds will average 15 to 25
mph with higher gusts. Some blowing and drifting is possible, but
given the wet, heavy nature of the snow, do not think that it will
be a large concern. It will likely impact visibility during the
snowfall, reducing it at times, but it is not expected to create
true blizzard conditions. Temperatures will remain somewhat steady
overnight, then fall slightly late tonight into Wednesday. Highs
Wednesday will be in the 20s.

Headlines remain in good shape, so will leave them going as is.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 255 PM CST Tue Jan 24 2017

Quieter weather pattern in the extended with amplified northwest
flow prevailing through the middle portions of next week. Could
still see some light snow lingering into tomorrow evening, with a
little blowing snow.  Have sided with CONSMOS values on winds
Wednesday night into Thursday morning. On the backside of the
departing system, will see 925 hpa temps tumble to around -10C
resulting in below normal temperatures on Thursday into Friday.
Temperatures moderate into the weekend, though remaining snow pack
will limit the potential warming.

Doesn`t appear as though there will be any large scale precipitation
systems in the next week. Have removed spurious pops through the
extended but left pops across southwest Minnesota next Tuesday as
more organized system drops down in northwest flow.  Right now,
appears that the focus would be further east, but could get brushed
by the system.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 516 PM CST Tue Jan 24 2017

Snow with IFR conditions will continue across the area into mid
morning on Wednesday, before tapering off from west to east in the
afternoon. In addition, northerly winds will increase tonight,
with gusts of 25 to 30 kts into Wednesday. This may result in
patchy blowing snow, though mainly at times when snow is actually
falling.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning until noon CST Wednesday for SDZ050-052>071.

     Winter Weather Advisory until noon CST Wednesday for SDZ038>040.

MN...Winter Storm Warning until noon CST Wednesday for MNZ080-089-097-
     098.

     Winter Weather Advisory until noon CST Wednesday for MNZ071-072.

     Winter Storm Warning until 6 PM CST Wednesday for MNZ081-090.

IA...Winter Storm Warning until noon CST Wednesday for IAZ001-012-020-
     031.

     Winter Storm Warning until 6 PM CST Wednesday for IAZ002-003-013-
     014-021-022-032.

NE...Winter Storm Warning until noon CST Wednesday for NEZ013-014.

&&

$$

SHORT TERM...
LONG TERM...BT
AVIATION...JM


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