Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Aberdeen South Dakota
1237 am CDT Friday Apr 25 2014

Update...
see below for aviation forecast discussion for the 06z tafs.

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Previous discussion...
short term...tonight through Saturday night
a short wave trough...steep lapse rates and limited moisture were
resulting in high based virga/light showers in northeast South
Dakota late this afternoon. These will continue to move east and
out of the region through the late evening hours. Have in slight
chance probability of precipitation at this time for this area. Otherwise...the breezy/windy
and dry northwest winds will fall off by late evening. The relative humidity and
winds will be enough to keep the red flag warning going into the
early evening. Otherwise...with a weak/diffuse surface pressure
gradient tonight...expect the winds to decouple late this evening
and become light and variable with mostly clear skies. Friday will
be another mostly sunny day with not much for winds along with
warmer temperatures. For Friday night through Saturday night...the
County Warning Area will start to receive the influences of the large upper low
pressure trough moving into the western US and into the central US
by the end of the short term. Some short wave energy kicking off
of this trough along with warm air advection is expected to bring a few showers
to the western and northern County Warning Area later Friday night and Saturday
morning. The surface pressure gradient and winds will pick up
Friday night and Saturday as a surface low pressure strengthens
in eastern Colorado. The winds will be from the east and northeast
bringing in cooler air for Saturday. Much better chances of
showers and thunderstorms are expected across the County Warning Area on Saturday
night as deep layer lift intensifies over the region along with
higher dew points advecting into the region.



Long term...Sunday through Thursday

Big story in the extended period is the large low pressure system
that sits and spins over the region during the first part of the
period. Models all in pretty good agreement in bringing a closed
low into the region with widespread rainfall. Models showing the
main surge of rainfall Sunday night. Will have to watch for
possible dry slot on Monday...which is suggested by the GFS.
Potential exists for low pressure and associated rainfall to
remain in the region all the way into Tuesday.

With all the clouds and precipitation expected with the storm
system...temperatures will stay on the cool side with generally 50s or
upper 40s for highs. Models try to develop an interesting pattern
late in the period with a huge longwave trough across much of the
central and eastern Continental U.S....keeping temperatures across this area
somewhat on the cool side...not nothing too extreme.

&&

Aviation...
06z tafs for the kabr...Katy...kpir and kmbg terminals

Kabr/Katy could see a brief period of fog between 09z and
15z. Otherwise...good VFR is expected over the next 24 hours with
surface high pressure setting up across the region.



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Abr watches/warnings/advisories...
South Dakota...none.
Minnesota...none.
&&

$$
Update...fowle
short term...mohr
long term...tmt
aviation...fowle

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