Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Aberdeen South Dakota
632 am CDT Monday Sep 22 2014
see updated aviation discussion below.
short term...today through Wednesday
Broad surface high across much of the region this morning with
just a light southerly wind over the County Warning Area. Temperatures are falling
through the 40s with abr just now falling to 39 degrees. As the
day progresses...southerly winds will increase with temperatures a few
degrees warmer than Sunday. Upper level shortwave energy will
approach from the west...but models suggest any precipitation today will
stay across southwest/south central South Dakota. Will hold off on
mentioning precipitation in the grids until this evening. Decent
agreement amongst the models on this system. As upper level energy
moves northeast overnight through Tuesday...chances will increase
across eastern South Dakota and western Minnesota. Not much instability so looking
at general showers with a few thunderstorms as well...not
expecting severe storms. This is the main feature through the
short term period. The upper level wave still lingers over eastern
portions of the County Warning Area into Wednesday...and will have to monitor for
possible addition of precipitation mention into Wednesday morning...but
for now forecast is dry.
Long term...Wednesday night through Monday
A building upper ridge will dominate the beginning of the extended
period. The ridge will bring dry conditions and warmer than
average temperatures to the region. Models really begin to diverge
on Sunday. A regime change is in the works with a deep upper
trough shifting east. However the GFS is a lot quicker with the
shift than the European model (ecmwf) and different precipitation forecasts reflect that.
Tried to trend the initial allblend probability of precipitation more toward the European model (ecmwf) as
these regime changes are notoriously slower than prognosticated.
12z tafs for the kabr...Katy...kpir and kmbg terminals
VFR conds expected for all terminal locations through valid
forecast period. High pressure will shift southeast through 15z
Monday...allowing surface winds to become south to southeast for all
locations by 15z Monday.