Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Aberdeen South Dakota
1216 am CDT Sat Aug 2 2014
see updated aviation discussion below.
No major changes to the forecast this evening...though did make a
few minor tweaks. Increased probability of precipitation a bit west of the Missouri as
storms continue to develop along an outflow boundary and are
moving east into central South Dakota. Also lowered overnight lows in
Aberdeen a few degrees based on recent trends.
short term...tonight through Sunday night
Currently seeing very isolated showers/thundershowers across
eastern Dakotas/western Minnesota. Expect this trend to continue through
the afternoon while focus shifts to western South Dakota development over
the next couple hours. Hi res models still latching onto this idea
with storm development within the weak surface low/boundary sliding
southeast through the region. Although not overly
impressive...instability and shear are evident across central South Dakota
so a few storms could be capable of hail and gusty winds by this
evening. Given the inverted v shaped soundings...gusty winds
probably more likely. Whatever activity moves/develops across
central South Dakota later on may be able to sustain itself some overnight
as both the NAM and GFS are showing a modest low level jet
pointing right into central/south central South Dakota.
Entire pattern in the short term is basically defined by ill
defined waves/boundaries crossing the region within weakly
unstable environment. This makes forecasting convection difficult
with no real significant boundaries or short waves to hang your
hat on. This will be the case on Saturday and Sunday with perhaps
the focus for Saturday afternoon/evening shifting to northeast South Dakota.
Have inserted slight chances for Saturday afternoon across the
Will see additional energy aloft moving in Sunday into Sunday
night...but again it is rather weak with no real significant surface
boundaries and an overall weakly unstable environment. Will
unfortunately have to stick with rather low probability of precipitation until some of
these storm clusters form or get picked up by hi res models.
Long term...Monday through Friday
Overall forecast trend for extended not changing much. Mean ridge
will slowly shift east and weaken as shortwave energy Delaware-amplifies
the pattern. Will see a chance of showers and thunderstorms most
days...with best chances of precipitation by middle week. Flow looks to
fairly weak during this time however. Temperatures will continue on a
cooling trend through the period to near or below normal temperatures by
06z tafs for the kabr...Katy...kpir and kmbg terminals
Primarily VFR conditions are expected through the taf period.
Scattered showers and thunderstorms will be possible across
central South Dakota...especially near kmbg. Visibility may briefly fall
to IFR in heavier thunderstorms.