Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 290829

Area Forecast Discussion
National Weather Service Sioux Falls SD
329 AM CDT Wed Mar 29 2017

.SHORT TERM...(Today and Tonight)
Issued at 328 AM CDT Wed Mar 29 2017

Surface low pressure across southeastern Kansas will make little
headway east today.  Band of rain over western Iowa associated with
700 mb frontogenetic forcing will gradually lift north and west
expanding into much of northwest Iowa today.  Have continued the
trend of keeping categorical pops there, with lesser chances of
precipitation to the north and west. Where it precipitates, will be
a struggle to get temperatures out of the 40s.  Portions of central
South Dakota will stay dry, and outside of high clouds, may clear
out leading to above average temperatures.

Precipitation will continue through the overnight hours across the
east.  Interesting set up with sub-freezing profile in the deep
saturation near the surface, but the dendritic layer remains
unsaturated aloft.  If the dendritic layer was to saturate, have a
slight chance of snow mention near Jackson MN, but think that
precipitation should mainly remain as rain.

.LONG TERM...(Thursday through Tuesday)
Issued at 328 AM CDT Wed Mar 29 2017

System will be on its way out Thursday morning, though should see
some light precipitation lingering in parts of northwest Iowa into
the morning. Low level temperatures along with decreasing moisture
aloft continue to support mainly rain. Precipitation and clouds will
hold temperatures in the 40s across our east on Thursday, while the
areas along and west of the James Valley climb into the 50s with a
little better shot at some afternoon sunshine.

We will be between systems Friday into early Saturday, with some
partial sunshine and warming temperatures expected. By later in the
day Saturday, the next upper trough swings out of the Four Corners
region into the southern Plains. This system could sling a little
light rain into our far southern areas Saturday afternoon/evening,
but with low level warm front south of I-80 and low level ridging
maintaining an influx of drier air into much of our area from the
east-northeast, it looks like rainfall will be quite limited and
will keep lower end pops confined to areas south of I-90. Overall,
weekend temperatures look seasonably mild, with highs in the 50s and
lows in the 30s.

Early next week, the southern Plains system deepens and continues to
track east through the Lower Mississippi Valley Monday, then lifts
into the Ohio Valley on Tuesday, while yet another upper trough digs
into the Rockies. Subtle mid-upper level ridging between these two
systems, which should keep our area on the drier side Monday into
Monday night. 29/00Z ECMWF trended toward the GFS/GEM in portraying
this solution, which lends a little confidence in lowering pops in
these periods. Did not remove pops completely, however, as previous
run of the ECMWF and some GFS ensemble members are either weaker
with the ridging, or have completely different timing/track of the
troughs, and thus cannot rule out precipitation entirely. For now,
though, the better chance for this forecast period does look to be
Tuesday, as the upper low begins to swing into the High Plains. This
system currently forecast to slide into the central Plains later
Tuesday night/Wednesday, which would bring more likely precipitation
chances to our area just beyond the current forecast period. At this
time, temperatures expected to remain warm enough for all rain, with
possibly some isolated thunder, as some weak instability is shown by
the GFS/GEM into far southern portions of the area on Tuesday. ECMWF
farther south and more stable, though, and with uncertainty in how
things will evolve at this point, will leave thunder out for now.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1044 PM CDT Tue Mar 28 2017

VFR conditions expected through the period north of I-90, while
areas along and south will experience MVFR and IFR conditions.
Rain will develop overnight along the Missouri River, bringing
MVFR ceilings and visibilities to SUX by morning with some MVFR
ceilings moving into FSD later on Wednesday.




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