Scientific Forecaster Discussion

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Area forecast discussion...updated 
National Weather Service Aberdeen South Dakota
1225 am CDT sun Apr 20 2014

no major changes planned for the forecast at this time. Surface high
pressure over the region this evening is keeping the area dry and
warm...with an expected cool off after sunset.

See updated aviation discussion below.

Previous discussion...
short term...tonight through Monday night

Weak high pressure will be the dominant feature over the area
tonight...keeping conditions dry. A cold front will approach the
area on Sunday and will cross the County Warning Area Sunday evening. Both the GFS
and European model (ecmwf) indicate the potential for precipitation along the front
Sunday evening...mainly across the eastern two thirds of the County Warning Area.
Weak lift and small amount of cape across the southern County Warning Area may aid
in the development of a few thunderstorms. High pressure settles
back in over the northern plains Sunday night through Monday
night...bringing dry conditions back to the County Warning Area.

Warmer air ahead of the approaching front on Sunday will bring
high temperatures into the 70s. Will then see slightly cooler air
on Monday...but highs should still reach near to slightly above
normal with mainly 60s expected. Overnight lows will be in the middle
30s to lower 40s through the period.

Long term...Tuesday through Saturday

Upper level riding on Tuesday quickly transitions eastward as a
western Continental U.S. Trough nears The Rockies. Models still show many
differences...with the European model (ecmwf) still the faster and furthest north
solution as compared the GFS/Gem. Regardless...precipitation chances will
begin Wednesday under diffluent southwest flow aloft...and with
strong warm air advection and Gulf moisture advecting northward.
The best chances for convection remain around the Wednesday
afternoon and evening time frame. The main upper low then moves
over the northern plains...either closing off and occluding over
the region by Thursday as the GFS/Gem would suggest...or a more
progressive open wave that nears the Great Lakes region before
becoming stacked as depicted by the European model (ecmwf). The uncertainty
manifests itself in continuous probability of precipitation through Friday. Conditions
should dry out by Saturday as another upper ridge builds over the
central Continental U.S..


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

VFR conditions will prevail through the taf period. Light and
variable winds tonight will increase out of the south to southeast
Sunday afternoon. A weak shortwave will move through the region
late in the taf period. Winds will shift to the northwest behind
this wave. No restrictions to ceilings or visibilities are anticipated.


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


short term...Parkin
long term...serr