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Area forecast discussion for western South Dakota and northeastern Wyoming
National Weather Service Rapid City South Dakota
212 am MDT Wed Mar 29 2017

Short term...(today through Thursday night)
issued at 211 am MDT Wed Mar 29 2017

08z surface analysis had weak high over the County Warning Area and inverted
trough across eastern NE into eastern South Dakota. Water vapour loop showed
upper low entering Texas Panhandle with precipitation shield mainly
southeast of the cwa, although some weak returns/-ra noted over
south central South Dakota under weak 75kt jet streak aloft.

Today, upper low moves northeast with lingering lift exiting the County Warning Area
this morning and staying southeast of the County Warning Area this afternoon. Patchy
fog expected early this morning given tight T/TD spreads and general
moistness of boundary layer. Sunshine will develop in the afternoon
with highs slightly above normal and near guidance.

Tonight, another upper trough crashes the northwest US coast pushing
shortwave ridging and weak low level return flow over the County Warning Area. Lows
will be near guidance.

Thursday, upper trough splits with main energy diving into The Four
Corners area. Return flow increases with surface trough moving into
the western portions of the County Warning Area. Pops warranted with best chances
Thursday night in the far west where 850-700mb frontogenesis
combined with synoptic lift to produce a band of mostly rain.
Temperatures may become cold enough late Thursday night for some
snow over northeast Wyoming into the Black Hills, but accumulations will
be minor.

Long term...(friday through tuesday)
issued at 211 am MDT Wed Mar 29 2017

Friday, aforementioned upper low digs deep into the southwest US
with lingering lift supportive of some rain over mainly southwest
half of the County Warning Area. Could be a bit of snow early. Temperatures will
be near guidance.

Saturday through Monday, a bit of rain possible under weakly
unstable flow aloft.

Tuesday, better looking storm system approaches from the west with
upper low bringing pops to the County Warning Area. Disagreement with timing and
placement of low; something one would expect for day 7, but
something to be watched.

&&

Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 211 am MDT Wed Mar 29 2017

Widespread MVFR/IFR ceilings will continue through early this morning
with local IFR/LIFR visibilities due to patchy fog, especially near the
Black Hills. Conditions will improve from west to east later this
morning through the afternoon hours. Widespread VFR conditions
expected tonight.

&&

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

$$

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