Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 160209 AAB

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
809 PM CST Sun Jan 15 2017

Issued at 808 PM CST Sun Jan 15 2017

Forecast is on track for the remainder of the night, thus no major
changes anticipated.


.SHORT TERM...(This Evening through Tuesday Night)
Issued at 321 PM CST Sun Jan 15 2017

Temperatures continued to elude guidance today and failed even to
reach adjusted expectations. Have decreased lows tonight to below
zero across the James Valley and areas of deeper snowpack across
Dewey and Corson counties as winds should be light with mainly only
high clouds encroaching from the south overnight. 925mb cold air
advection, snowpack, and light winds should make it a struggle for
temps to rise out of the teens again Monday across much of central
South Dakota. Have adjusted temps accordingly, though they still may
be overdone for some.

Regarding Monday`s storm system, have eliminated all POPs across the
CWA. The 12z model run consensus continued trending precipitation
further southeast. Therefore, dry conditions are expected throughout
the short term across the CWA as a western U.S. upper level ridge
builds in by Wednesday.

.LONG TERM...(Wednesday through Sunday)
Issued at 321 PM CST Sun Jan 15 2017

Main highlight of the extended period will be the much anticipated
warm up which begins Wednesday and lasts into the weekend. Although,
the big question will be just how much of an effect will snow cover
have on temperatures. Judging how big of an impact it has been
recently, mainly from the James valley into central SD, have some
real concerns that inherited SuperBlend temps are several degrees
too warm. Although the air mass is much warmer by mid-week, with
925mb temps anywhere from +6C to +9C, there still is not much in the
way of mixing. Winds should be around 10 knots, so this is just
enough to mix down some of this warmer air aloft, and feel we should
be able to see the 30s for most areas. Although, felt it was
necessary to lower highs across central/north central SD into the
James valley where snow cover is the deepest. Lowered them more into
the lower 30s on Wednesday. MBG has fallen short of forecast highs
by about 10 degrees the past few days so will really have to watch
our forecast highs over the snow field. Have a feeling SuperBlend
temps for overnight lows are also too high during the nighttime
hours whenever there are mostly clear skies and generally light
winds. Thank the snow cover once again. Seemed like ADJECE had a
better handle on overnight lows, but mainly inserted these numbers
into the Wednesday night grids for the time being to prevent getting
too carried away. Will have to watch trends over the next few days
but will keep in the back of our mind that anything inherited from
SuperBlend is probably too warm for central/north central SD into
the northern James valley.

As for precipitation, things look dry until late week into the
weekend when an upper level low tracks northward into the area.
Still a wide range of different solutions amongst the models in
regards to evolution of upper level and surface features as the
system moves through, so did not stray away from inherited
SuperBlend POPs at this time until clarity surfaces.


.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 507 PM CST Sun Jan 15 2017

VFR conditions are expected at all terminals through the taf valid




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