Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Aberdeen South Dakota
1224 am CDT Wednesday Oct 22 2014
see updated aviation discussion below.
short term...tonight through Thursday night
an upper level trough of low pressure currently crossing western
Wyoming...will move across the region late tonight and through the
day on Wednesday. Low level moisture will advect into the region
ahead of this system with dew points climbing into the upper
40s/lower 50s by 18z Wednesday. There is also some weak mu-cape
values exceeding 500 j/kg which could cause a few thunderstorms.
Models agree well with locations along and east of the James River
Valley of having the best potential of seeing showers. Thus have
increased probability of precipitation in the eastern County Warning Area during the afternoon hours.
Conditions quickly dry out behind this system with precipitable waters dropping
from over an inch...to under a half inch. Above normal
temperatures along with dry conditions will remain across the
region through the rest of the short term.
Long term...Friday through Tuesday
upper level ridging will dominate the extended pattern until late
Sunday when the ridge shifts east. A surface low will move through the
Dakotas on Sunday. High temperatures will be well above average under the
ridge..especially coupled with good mixing at the surface due to the
surface low. With 850 mb temperatures topping out near +20c on Sunday morning
highs at the surface will be in the 60s and 70s Friday through Sunday.
There is a lot of divergence in the models as to just how much
precipitation may be associated with the upper trough that will move in
on Monday...though latest runs are all leaning toward the dry
side. Stuck with superblend probability of precipitation for now due to run to run
inconsistency. Either way the upper trough will be short lived
with more zonal flow taking over aloft on Tuesday. Surface temperatures are
expected to fall to around average..in the 50s..with and behind
the upper trough.
06z tafs for the kabr...Katy...kpir and kmbg terminals
Mainly VFR conditions are expected across the region through
Wednesday. A cold front will move east over the terminals on
Wednesday...with a chance for showers.
Short term...South Dakota