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Area forecast discussion 
National Weather Service Aberdeen South Dakota
240 PM CDT Monday Aug 31 2015

Short term...(this evening through Wednesday night)
issued at 234 PM CDT Monday Aug 31 2015

The forecast challenge appears to be temperatures.

Currently...temperatures are in the 70s and 80s. A cold front is
working into eastern South Dakota and skies are partly to mostly
cloudy over most of the forecast area. There is a skinny band of
light rain showers slowly working east-northeast over the middle of
the state.

The forecast does not really Bode all that well for precipitation
chances beyond the tonight period. After tonight...no low level
forcing or fronts to initiate convection off of in the short term.
Warm middle-level capping temperatures still applies this go around through
middle-week as well...despite the return of low level moisture and
instability.

In southwest flow aloft...models keep most of the better middle and
upper level westerlies off to the north and west...and forecast the cold
front to stall out/dissipate across the Dakotas border with
Minnesota tonight...so if clouds/precipitation go away later tonight
leaving winds light and skies clear across the eastern County Warning Area...there
could be some fog by morning...given the high dewpoint readings
currently over that area. Not confident enough to add fog mention at
this time. But something to watch.

By Tuesday afternoon...the forecast area sets up in a prolonged
period of southerly return flow right into Wednesday night. The
catch is while low level warm air advection will be occurring over the
County Warning Area...expecting to see the same tricky issue with mixing. Do
boundary layer mixing winds keep a southeasterly component and limit
mixing...thereby limiting how warm we can get? Or does a portion of
the western zones feel the influence of a more southwesterly
component of wind for better mixing Tuesday and Wednesday...thereby
increasing the likelihood of once again achieving middle to upper
90s for highs those two days? Over the past couple of days...lack
of a westerly component to the boundary layer wind has resulted in
markedly lower high temperatures than capable of reaching especially
throughout and east of the James River Valley. The high
temperature forecast will require some increased scrutiny /perhaps
considering bias-corrected guidance as a starting point?/.

Long term...(thursday through monday)
issued at 234 PM CDT Monday Aug 31 2015

Lowered temperatures a few degrees across the eastern County Warning Area on Thursday
compared to what superblend gave. Thursday looking very similar to
what we saw on Sunday in regards to 850 mb temperatures and winds. Had
trouble reaching upper 80s and low 90s over eastern areas of the County Warning Area
and superblend gave similar temperatures for Thursday. As for precipitation
chances...it appears pattern gets fairly active beginning Friday as
a frontal boundary moves into the Dakotas then stalls. A couple
surface waves of low pressure then track along this boundary through
the weekend which should bring rain chances to the region.

&&

Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1229 PM CDT Monday Aug 31 2015

A weakening cold front it making its way across the region. Kpir
and kmbg have already seen the passage and have northwest winds
that will slowly diminish to light and variable by this evening.
Kabr will see northwest breezes this afternoon with frontal
passage right around 18z. Katy will gradually see southwest winds
switch to northwest over the next several hours. VFR conditions
are expected through the taf forecast period. A few very light
showers or sprinkles are moving across central South Dakota so will include
a vcsh mention at kpir for a few hours this afternoon.

&&

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

$$

Short term...dorn
long term...tmt
aviation...tmt

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