Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 162115

Area Forecast Discussion
National Weather Service Aberdeen SD
315 PM CST Tue Jan 16 2018

.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 313 PM CST Tue Jan 16 2018

Surface high pressure currently over the eastern part of the state
will slowly begin to drift off to the southeast tonight, with a more
moderate air mass beginning to set up. May see a bit of a downslope
wind event over the Coteau tonight into tomorrow morning as well,
but with very little snow on the ground, expect the main effect to
just be the potential for some patchy blowing snow along the higher
elevation areas. Will see temperatures fall into the single digits
above and below zero tonight, then the warmer air begins to take
over, with highs in the upper 20s east to the lower 40s west on
Wednesday afternoon.

.LONG TERM...(Wednesday Evening through Tuesday)
Issued at 313 PM CST Tue Jan 16 2018

Thursday: Early in the day there is a shortwave moving across the
Western Lakes region, however there is limited reflection of this
feature below 10kft, and as such should be nothing more than
mid/high clouds across the northeast, if anything at all. This
will be followed by weak ridging aloft. Closer to the surface we
can expect a warm advection pattern to continue with 925mb
temperatures around a standard deviation above climo. Mixing will
aid in warming temperatures thanks to a westerly component, plus
we have the added benefit of a lack of consistent snow cover. As
such, guidance mixed temperatures to 900mb between the GFS/NAM are
in the upper 40s to low 50s east river. Added a few degrees to
blended guidance given our propensity to beat guidance this

Friday: We will see even better mixing. First, there is the
possibility for some ducting and downslope winds across the Sisseton
hills, however peak winds in this layer are only around 30kts so
nothing too windy. This will also keep temperatures up overnight
(morning lows Friday AM in the 20s, or close to average highs).
We have a weak surface trough crossing the area as well, with a
southwest component before shifting to northwest, which will also
enhance mixing.

We have high confidence on temperatures for both of these days. As
we move into the weekend and address an approaching storm system,
confidence is much much lower.

Saturday: Suppression of the ridge begins with a deepening western
CONUS trough. 500mb moisture increases so anticipate increased high
clouds. 925mb temperatures will fall to around 0C, so we can still
expect readings Saturday above average.

Sunday/Monday: We continue to see a good signal for a Colorado low,
though the track and intensity have varied between deterministic
guidance, along with a wide range in outcomes from ensembles. There
is consistency with a surface low developing near the Oklahoma
panhandle but models begin to diverge somewhat from there. The
majority of outcomes support the bulk of the moisture with this
system traveling just south of the CWA. Again, given that there
hasn`t been much for consistency in trends, and that we are still 5
days out before this system could impact the region, it is not
outside the realm of possibilities that it could effect us and is
something to watch. Unfortunately 12Z blended guidance was personally
too high for my taste with the 00Z ECMWF and 12Z Canadian models
taking a northerly (and more impactful) track compared to the 12Z
GFS. Looking at the GEFS as well as seeing a quick jog back to the
southern track within the 12Z ECMWF and most of those ensemble
members, decided that the previous forecasters POPs were much more
in line with thinking compared to blended guidance.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1126 AM CST Tue Jan 16 2018

VFR conditions will prevail across the area through midday




LONG TERM...Connelly
AVIATION...Parkin is the U.S. government's official web portal to all federal, state and local government web resources and services.