Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
230 PM MDT Wednesday Jul 27 2016

Short term...(this evening through Thursday night)
issued at 228 PM MDT Wed Jul 27 2016

20z surface analysis had a frontal boundary from southwest Montana
into the Black Hills into central NE, and then winding back into
central Minnesota. Distinct compact shortwave noted over northeast Wyoming per
water vapour loop, which is assisting on going convection over
parts of the County Warning Area this afternoon. Activity developing in a 1-2kj/kg
MLCAPE regime. Mlcin about gone most places. 0-6km effective
shear 15-20m/S, which will be enough for a couple of strong to
severe storms through this evening.

Overnight, subsidence behind departing shortwave will bring a
respite from storms, but a stronger wave will push southeast into
the County Warning Area late tonight. It will be preceded by a 20-30kt low level jet
and associated Theta-E advection. Guidance has been consistent
bringing a blob of precipitation through the County Warning Area with embedded
thunderstorms. Have upped pops to account. Temperatures will be near
guidance.

Thursday, overnight storms will slowly shift southeast with daytime
recovery limited so suspect additional storms will be less active
than previous days. Temperatures will be near guidance.

Long term...(friday through wednesday)
issued at 228 PM MDT Wed Jul 27 2016

Chances for showers and thunderstorms will continue Friday,
mainly over the eastern County Warning Area where upper energy will be focused.
Highs will be in the 80s.

With weak upper ridging briefly over the region this weekend, warmer
and drier conditions are expected. Isolated thunderstorms will
remain in the forecast for the weekend. Towards the end of the
weekend, the Canadian low pressure system will push the ridge
eastward, placing the northern plains back in more active zonal to
southwest flow. Above average temperatures will continue into early
next week.

&&

Aviation...(for the 18z tafs through 18z thursday)
issued at 228 PM MDT Wed Jul 27 2016

A band of showers/storms across northwest South Dakota into the
Black Hills will continue to move eastward this afternoon, with
IFR to MVFR conditions around heavier showers and storms. Mainly
VFR conditions expected by early evening as showers and storms
move east and south of the area. Additional rain showers with MVFR
conditions expected across northeast Wyoming and western South Dakota by
early Thursday morning.

&&

Unr watches/warnings/advisories...
South Dakota...none.
Wyoming...none.
&&

$$

Short term...helgeson
long term...15
aviation...15

National Weather Service Glossary of Abbreviations