Scientific Forecaster Discussion
fxus63 kunr 171117
Area forecast discussion for western South Dakota and northeastern Wyoming
National Weather Service Rapid City South Dakota
517 am MDT Mon Jun 17 2019
Discussion...(today through sunday)
issued at 347 am MDT Mon Jun 17 2019
Current upper level analysis has weak closed low over northern
Minnesota with generally zonal low across the northern rockies and
northern plains. Skies are variably cloudy across the northern
plains with a few showers crossing the Black Hills and northwest
South Dakota at the moment. At the surface, weak cold frontal
boundary lingers across western South Dakota with light northeast
winds to the north, and light westerly winds to the south of it.
Temperatures across the forecast area at 3am are in the upper 40s
Seasonably cool airmass will linger over the Dakotas early this
week, as upper flow remains zonal to weakly cyclonic. This will
keep highs mainly in the mid 60s to mid 70s. Weak energy moving
through northwest flow will keep chances for showers and
thunderstorms around, although weak instability should hamper the
On Tuesday night into Wednesday, a low pressure system over
southwestern Canada will begin approaching the northern plains.
The surface low is progged to cross the County Warning Area Wednesday morning,
with a line of thunderstorms ahead of the trof/warm front, mainly
across western South Dakota. Marginal instability and shear could result in
a few stronger storms Wednesday afternoon. Better upper level
support will push into the area Wednesday evening, and a cold
front will begin crossing the County Warning Area. Better Post-frontal shear, as
well as some marginal instability, could result in some strong to
severe storms Wednesday evening.
Thursday will only see slight chances for precipitation, before
the main energy associated with the upper low swings into the
region later in the day. More showers and thunderstorms can be
expected Thursday night into Friday. Although models differ on the
track of the low, another cool weekend will be possible.
Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 515 am MDT Mon Jun 17 2019
Area IFR fog/low stratus over portions of southwest South
Dakota will dissipate this morning. Showers and thunderstorms
will redevelop this afternoon and continue into tonight.
MVFR/local IFR conditions expected with the precipitation.