Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Aberdeen South Dakota
532 am CST Monday Nov 24 2014
see updated aviation discussion below.
short term...today through Wednesday
precipitation has changed over to snow in the
Coteau/Minnesota...so dropped freezing rain advection. With only low end
scattered coverage...doubt anything more then a dusting
accumulation. With cold advection today...winds will continue
right around advection level in the far east...and temperatures will
struggle to warm much.
Will see a brief period of warm air advection tonight. Profiles
go from very dry around 800-850mb to saturated below 5kft...which
is a low confidence red flag. Temperatures at the top of this layer are
cold enough to get some light snow...but that is only prognosticated to
last an hour or two before ice is no longer available. Will likely
just see a combination of fog/stratus if anything develops at
all...but if we see fog...there may be some deposition/icy roads
to watch for.
Models continue to bring in a clipper system Tuesday with decent
track and timing consistency. Sref probabilities for an inch are
between 60 and 80 percent at this point. Will have to further
evaluate winds with around an 8-10mb pressure gradient across the
state and a 10mb/6hrs pressure bubble early Wednesday.
Long term...Wednesday night through Sunday
may be some light snow ongoing across the western County Warning Area when the
extended period begins...but should quickly come to an end as high
pressure drops over the area from the north. This high will get
pushed east on Thursday as a trough digs down the Lee of The
Rockies. Current models are in somewhat decent agreement that
precipitation with this system will remain north of the County Warning Area...but
the European model (ecmwf) and Gem hint at the northeast County Warning Area getting clipped
Thursday night...so will keep a small pop in during that time. The
remainder of the period looks dry at this time as high pressure
drops in behind the exiting low pressure system over the weekend.
Temperatures will generally be below normal...with highs in the
teens and 20s. The exception will be Friday when some warm air advection
develops and highs will be mainly in the 30s.
12z tafs for the kabr...Katy...kpir and kmbg terminals
MVFR ceilings will slowly push eastward over the central and eastern
part of the County Warning Area through the morning hours. Some light snow is
possible as well...with visibilities falling into the MVFR category at
times. Northwest winds of 20 to 35 miles per hour will persist across the
east through midday. By this afternoon...VFR conditions will
return and will then prevail through the remainder of the taf
South Dakota...Wind Advisory until noon CST today for Clark-Codington-day-Deuel-
Minnesota...Wind Advisory until noon CST today for Big Stone-traverse.