Scientific Forecaster Discussion
fxus63 kunr 280814
Area forecast discussion for western South Dakota and northeastern Wyoming
National Weather Service Rapid City South Dakota
214 am MDT Wed Jun 28 2017
Discussion...(today through tuesday)
issued at 208 am MDT Wed Jun 28 2017
Upper wave is moving through the northern plains, and storms have
shifted east into Minnesota and Iowa. Water vapor shows a weak wave across
northwestern WY, a stronger wave moving into ID, and a low
spinning over Washington. Surface winds are northwesterly around 10 kts,
and temps range from the lower 50s across northeastern Wyoming to the
lower 70s across south central South Dakota.
Initial wave will push into northeastern Wyoming by 18z, indicated in the
models by a line of frontogenesis and q-vector convergence. Expect
storms to develop across northeastern Wyoming and the Black Hills early
afternoon, then expand across western South Dakota during the evening as
the stronger, secondary wave moves in. While ml cape of 600-1000
j/kg is significantly weaker than yesterday's instability, 0-6 km
shear around 50 kts will be sufficient for isolated strong to
severe storms. Showers and thunderstorms will continue overnight
and into Thursday, moving out of the County Warning Area Thursday night.
Highs today will be in the mid 70s to upper 80s, warmest across
south central South Dakota. Cooler air will pour into the northern plains
Thursday as the trough moves through, dropping highs about 10
One more piece of energy from the upper trough may bring a few
showers/storms to central South Dakota Friday, but otherwise dry weather is
expected Friday and Saturday as an upper ridge builds over the
western Continental U.S.. a wave will briefly flatten the ridge Sunday and
bring another round of showers/storms, but then dry weather will
return for early next week. A warming trend will also begin this
weekend, with highs returning to near 90 by the 4th of July.
Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1043 PM MDT Tue Jun 27 2017
Isolated showers will be possible tonight along with gusty northwest winds.
Another round of rain showers/ts will be possible Wed afternoon, with
local MVFR conds possible in/near ts.