Scientific Forecaster Discussion
fxus63 kunr 261102
Area forecast discussion for western South Dakota and northeastern Wyoming
National Weather Service Rapid City South Dakota
502 am MDT Wed Jul 26 2017
Discussion...(today through tuesday)
issued at 326 am MDT Wed Jul 26 2017
Upper level analysis shows high pressure across the Southern
Plains with an area of low pressure over Canada resulting in
southwest flow across the forecast area. At the surface, the cold
front is well south and east of the area extending from the Great
Lakes area though Nebraska with high pressure beginning to build
in from the west. Latest radar imagery has scattered light showers
over most of the area with the strongest convection remaining
just south of the area over Nebraska.
Hi-res models keep scattered light showers over the far southern
portions of the forecast area through the morning. Overall,
temperatures today will be cooler, but around average. A few
showers/storms are possible early this evening in northeastern
Wyoming, but most areas will remain dry.
The upper ridge begins to rebuild over The Rockies through the
weekend with Pacific moisture streaming into the northern plains. A
couple of weak shortwaves will round the upper ridge Thursday
afternoon/evening and Friday afternoon/evening, supporting the
development of some scattered storms. Modest cape combined with
upslope flow could result in a few organized stronger/severe storms.
On Thursday expect the main threat for storms to be over the Black
Hills and west with possible storms Friday afternoon/evening across
most of the area. Model sounding show drier lower levels, which
would make strong wind gusts the primary concern; however, hail
still can't be ruled out with stronger, more organized activity.
Expect most of the convection to be diurnally driven and diminish
overnight in coverage and intensity.
As the ridge continues to build for the rest of the weekend into
next week, small chances for storms will be possible everyday.
Temperatures through the middle of next week will be slightly above
Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 459 am MDT Wed Jul 26 2017
A few showers and thunderstorms will be possible today, mainly
across northeastern Wyoming. VFR conditions are expected through