Scientific Forecaster Discussion
fxus63 kunr 171122
Area forecast discussion for western South Dakota and northeastern Wyoming
National Weather Service Rapid City South Dakota
522 am MDT Tue Sep 17 2019
Discussion...(today through monday)
issued at 250 am MDT Tue Sep 17 2019
Current surface map places low across eastern Montana with trof
extending into eastern Wyoming into eastern Colorado. A few
mid/high clouds across the forecast area. Bl mixing/downslope
flow has kept temperatures on the warm side for this time
year...with several locations still in the mid 70s. Compact
shortwave moving through northern Nevada/southern Idaho. This
shortwave moves into the western Dakotas by early evening.
Surface low deepens across eastern Montana/western North Dakota
this afternoon, with trof crossing western South Dakota. Deep
mixing will result in gusty west-southwest winds behind the
surface trof. Steep mid level lapse rates and strong forcing will
bring scattered showers/thunderstorms this afternoon and evening.
Will be some strong/severe wind gusts with the thunderstorms
given abundant dcape. Showers/thunderstorms lift north and east of
the forecast area early this evening.
Western Continental U.S. Trof reloads Wednesday with shortwave ridging across
the northern plains. Will be a dry and warm day across the area. A
few thunderstorms possible over far south central South Dakota
Wednesday night with threat-E advection on nose of low level jet.
Upper level trof crosses The Rockies/High Plains Friday with
showers/thunderstorms. Cooler this weekend. With a few showers
Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 520 am MDT Tue Sep 17 2019
VFR conditions are expected to continue through the taf period.
SW winds will increase this morning, with gusts 25-35 knots
overspreading northeastern Wyoming and western South Dakota from west to east.
Rain showers/thunderstorms and rain may develop along a cold front crossing the region
this afternoon and evening. Sporadic strong wind gusts over 40
knots will be possible in the vicinity of these shra/tsra.