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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
843 am MDT Tuesday may 5 2015

issued at 843 am MDT Tuesday may 5 2015

Klbx radar is showing showers quickly developing across north central Nebraska
moving north toward scntrl South Dakota. This fits well with the hrrr/rap
which has some showers entering scntrl South Dakota before late morning/early
afternoon. Based on this...have made adjustments to probability of precipitation for the rest
of today...mainly to lower probability of precipitation across the western half of the
County Warning Area...and increase them over scntrl. No other changes needed at
this time.


Short through Wednesday night
issued at 252 am MDT Tuesday may 5 2015

Deep southerly flow will develop as the SW Continental U.S. Upper low ejects
to the northeast. This will allow ample ll moisture to spread
into the northern plains with increasing chances for rain today
into Wednesday. Middle/high moisture will advect into the region
today with an associated increase in clouds. A shortwave impulse
will eject out of the SW Continental U.S. Upper low this morning...slowly
lifting toward the forecast area with increasing deep layer lift
spreading northward this afternoon. Frontogenesis and isentropic lift
will develop in an increasingly unstable environment due to
diurnal heating this afternoon. This will support increasing shower/ts
chances across the forecast area...spreading from south to north
as deeper moisture is advected northward today. Best collocation
of deep ascent/fgen/upglide is expected tonight as a low level jet pushes
into central South Dakota. Temperatures will remain tricky in the
period...with cloud cover and increasing chances for rain
potentially hampering rises...especially on Wednesday.

Long term...Thursday through Monday
issued at 252 am MDT Tuesday may 5 2015

As the upper low spins over the West Coast...weak
energy will eject into the northern plains and will keep chances of
showers around for Thursday and Friday. Precipitation chances increase
Saturday as western trough/closed low moves into the central Continental U.S..
both the ecm and GFS are wrapping colder air around the low into the
County Warning Area...with 850mb temperatures around 0c. This could mean some precipitation falls
as snow Saturday night across the higher elevations of the Black
Hills...but still much uncertainty exists with the track of this

Temperatures from middle week into the weekend will be near to slightly
below the 50s and 60s with the ample cloud cover and
precipitation chances.


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 453 am MDT Tuesday may 5 2015

For the 12z tafs through 12z Wednesday morning issued
at 252 am MDT Tuesday may 5 2015

VFR conditions expected today across northern half of
County Warning Area...with some MVFR ceilings pushing into southern South Dakota and
northeastern Wyoming. Rain showers with some possible thunderstorms
will expand over the area this afternoon into tonight. MVFR
ceilings/visibilities in showers/storms...with local IFR conditions
possible...especially over higher terrain.


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


short term...10
long term...pojorlie

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