Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 281706

Area Forecast Discussion
National Weather Service Sioux Falls SD
1206 PM CDT Fri Oct 28 2016

.SHORT TERM...(Today and Tonight)
Issued at 329 AM CDT Fri Oct 28 2016

The main feature for today and tonight will be winds today. The
strongest winds will be in the Buffalo Ridge area of southwest
Minnesota this morning, but the strongest winds overall for the day
will be in part of northwest Iowa, from east up Sioux City to Storm
lake and up close to Spencer. That is, the far southeast corner of
our forecast area. Models show the potential for sustained winds a
little above 20 knots, with some gusts peaking at close to 30 knots,
or almost 35 mph. peak winds will drop off to the north and west of
this corner, while the early fairly strong winds in southwest
Minnesota near the buffalo Ridge should actually drop off a little
during the middle of the day. For fire weather, the strongest winds
today will be in the area of pretty healthy dew points, while winds
in the drier area out west will be modest, so fire danger should not
reach high anywhere today.

Dry air will rule today, except areas of moisture and clouds at very
high levels. The sky cover with these variable high clouds should be
think enough to dim sunshine a little, but models indicate that
these high clouds will tend to thin out some by early afternoon, so
heating from the late October sun angle will not be too hampered.
Temperatures still look to warm into the 70s, with around 80 near
and southwest of the Missouri River. Record highs are unlikely, with
our record of 79 at Sioux Falls, lower in relation to others, still
seeming a little out of reach.

Tonight will bring an increase and thickening of the high clouds,
along with the slow and not very dramatic slipping of a cold front
south over the area. The broad gradient developing near the front as
it approaches at the end of today will be the reason why any strong
afternoon winds will drop off pretty quickly at the end of the day.

Late tonight an area of isentropic lift associated with in
increasing thermal gradient will approach from the northwest. Middle
clouds will increase later tonight, but light rain or showers look
to hold off through 12z Saturday. A couple of the high resolution
models, including the NMM, almost touch the area west of Huron at
that time. This fits with he loaded pops just keeping mention out
of the area, so saw no need to adjust these. The slow start to the
cooling, going along with the very slow pickup in northerly winds
behind the front, will lead only to low temperatures in the 46 to 52

.LONG TERM...(Saturday through Thursday)
Issued at 329 AM CDT Fri Oct 28 2016

The main focus for the upcoming weekend will be on a shortwave
ejecting out of the central and northern Rockies into the northern
Plains Saturday and Saturday evening.

Scattered showers spread east across south central and east central
SD Saturday morning, then across the remainder of the forecast area
Saturday afternoon. without instability, will leave out anythunder
mention for this activity. Best chances for rain will be along and
north of I29 where moisture and forcing will be greatest.
Additionally, expect any rainfall amounts to be light, with most
locations seeing less than a quarter inch of rain. Winds will become
breezy from the north-northeast during the day, while cloudy skies
and cold air advection will cap temperatures well below Today`s
anticipated highs. Highs will range from near 50 north, to the mid
60s near Sioux City and Storm Lake.

High pressure quickly builds behind this system Saturday night as
upper level ridging also rebounds across the Plains. Stratus should
lift on Sunday with southerly winds tapping into warm air advection,
especially in south central SD/Missouri Valley. With the next active
shortwave approaching Sunday, flow turns southwesterly. Surface
winds will also increase throughout the day with strong mixing and
unseasonably warm temperatures aloft bolstering highs back into the
mid 60s to mid 70s. There is some question about the track of the
aforementioned shortwave. The GFS is quite a bit further south
than the ECMWF and GEM and brings some light precipitation into
southwest MN in the afternoon. Think that moisture will be
problematic in our area, so have left out any pops for Halloween.

Upper level southwest flow persists Tuesday into Wednesday. This
periods remains primarily dry with slightly above normal highs in
the upper 50s and lower 60s. Models suggest that a weak wave lifting
near our southeast border could bring some scattered showers to the
Storm Lake area Tuesday night, but the main threat looks just east
of our forecast area. Model certainty lowers for the second half of
the week, but are trending towards a drier forecast.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1204 PM CDT Fri Oct 28 2016

Dense shield of high clouds will gradually build down towards the
surface after 09z as disturbance approaches from the west. Could
see some MVFR to IFR ceilings develop north of Interstate
90...potentially affecting KHON.




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