Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 172326 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
526 PM CST Fri Feb 17 2017

Issued at 523 PM CST Fri Feb 17 2017

See updated aviation discussion below.


.SHORT TERM...(This Evening through Saturday)
Issued at 241 PM CST Fri Feb 17 2017

Windy conditions are expected to continue through the afternoon, but
subside towards sunset as the inversion sets up thanks to a weak
surface gradient. A weak surface high drifts to the south, and with
light winds and dewpoints in the 30s, a few spots may get some fog
towards morning, but guidance suggests this will not be widespread.

For Saturday, 850mb temperatures will initially start out around
+5/+6C, but warm advection out west will cause these numbers to
increase to around +10C, while in the east the change is essentially
neutral. Winds will be light and shifting to the south, so mixing
will be less efficient compared to today. Mixing to 900mb yields
highs in the mid 50s for the eastern CWA, and to 850mb into the
upper 50s for the Missouri valley. Snow cover will limit mixing for
locations north of Pierre however, so their highs will probably be
in the 40s again.

.LONG TERM...(Sunday through Friday)
Issued at 241 PM CST Fri Feb 17 2017

By Monday, southwesterly upper level flow will replace ridging as a
long wave trough tracks from west to east across the CONUS. The
center of the associated surface low is expected to track across
southern South Dakota late Sunday through Monday. A dry mid level
layer will be in place initially, so unsure how quickly saturation
will occur or if the forecast is a little quick bringing
precipitation back into the region. Regardless, warm air advection
and a surge of gulf moisture eventually take over, and combined with
weak to moderate forcing, there is a pretty good bet of at least
light rainfall across the CWA. The best chances remain over the
northeast CWA. Given the warm temps (925 MB temps ~10 C) and high
dewpoints (upper 40s/low 50s), instability is present and can`t
rule out rumbles of thunder Monday afternoon.

As the Monday system exits, zonal upper level flow takes over. A
very mild airmass remains in place, in fact, another warm air
advection push ahead of a weak short wave results in 925 MB temps
ranging from 10 C to nearly 20 C from northeast to southwest across
the CWA Tuesday afternoon. No precip expected with that shortwave

Attention then turns to a more significant system expected to
influence the northern plains Thursday and Friday. Still much too
far out to pinpoint the exact location of this system, and the
most recent model runs have trended slightly further south with
the track of the low. Plenty of moisture and forcing involved and
will be watching as details become more clear next week. Cold air
advection to follow on the backside of the system Friday.


.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 523 PM CST Fri Feb 17 2017

VFR conditions will prevail across the area tonight and through
the day Saturday.




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