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
503 PM MDT Thursday Sep 3 2015

Short term...this evening through Friday night
issued at 204 PM MDT Thursday Sep 3 2015

20z surface analysis had low over western ND with trough into
western OK and weak cool front into southern Idaho. Water vapor showed
shortwave over northern Colorado heading into southeast Wyoming/western NE.
Latest model guidance has a good handle on disturbance...which
will work north/northeast tonight along frontal boundary. Deep dry
mixing over County Warning Area has resulted in little MLCAPE over the western
half of the County Warning Area...with about 1kj/kg MLCAPE over the east...but
with decent mlcin. Expect high-based -tsra to sneak into County Warning Area late
this afternoon and then spread northeast overnight. Gusty winds a
threat through the evening hours given dcape/well-mixed boundary
layer. Temperatures will be near guidance.

Friday...leftover activity will wane in the morning with frontal
boundary remaining over County Warning Area. These boundaries will be focus for
-tsra late in the day into Friday night as easterly boundary layer
flow brings back low level moisture. It is likely a weak
disturbance will waft through the County Warning Area. Temperatures will be
tricky with some cloud cover concerns...so have lowered some in
the northwest but kept readings near guidance in the southeast
where thermal ridge/best mixing coincide.

Long term...Saturday through Thursday
issued at 204 PM MDT Thursday Sep 3 2015

Upper low will cross the northern rockies Sat and into the eastern Montana/western
ND sun. Models are still consistently showing the area getting dry
slotted through the weekend...although there may be a few
scattered showers/storms on Saturday. Continued the trend of
reducing probability of precipitation. Still looks pretty warm on Saturday ahead of the
low pressure system...with highs in the 80s and lower 90s. Cold
front will cross the area sun with cooler temperatures and breezy
winds...especially across northwest South Dakota. Slightly below average temperatures
will persist across the region through much of next week.
Showers/storms possible Monday night into Tuesday as another wave
pushes through the region...but otherwise next week looks mainly
dry.

&&

Aviation...(for the 00z tafs through 00z Friday evening)
issued at 501 PM MDT Thursday Sep 3 2015

Isolated/scattered thunderstorms and rain expected through this evening...especially over central
South Dakota. MVFR conditions and gusty winds are possible near these
storms. Additional scattered -shra possible in the morning across much of
the area...but VFR conditions expected.

&&

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

$$

Short term...helgeson
long term...pojorlie
aviation...Johnson

National Weather Service Glossary of Abbreviations