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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
351 am MST Wednesday Nov 26 2014

Short through Thursday night
issued at 249 am MST Wednesday Nov 26 2014

Latest water vapor images and upper analysis show upper trough over the
Midwest with a ridge over the Pacific coast. Fast 150kt jet flow
is diving into the forecast area from the northwest. The northwest-southeast oriented
baroclinic zone over the western part of the County Warning Area will intensify
today with increased middle-high level warm advection above the
colder air at thee surface. The baroclinic zone will gradually
move northeastward today and tonight. Frontogenetical forcing and
nearly saturated profiles will lead to periods of light snow or
flurries over northestern Wyoming and parts of far western South Dakota today.
The precipitation will spread northeastward tonight as upper heights
continue to build and low-middle level warm advection intensifies.
Sref ptype probabilities and NAM vertical profiles support a
chance of snow with a slight chance of freezing rain over parts of northestern Wyoming
and northwestern South Dakota late tonight into Thursday morning. There will be a wide
spread of temperatures on Thursday as the colder air retreats to
the east and warmer air moves in from the southwest. Highs are
expected to range from around 30f toward north central South
Dakota with highs around 50f over parts of northeastern Wyoming
and southwestern South Dakota. The precipitation over far
northwestern South Dakota in the morning will move away from the
area by afternoon...leaving dry weather and variable cloud cover
for Thursday afternoon.


Long term...Friday through Tuesday
issued at 249 am MST Wednesday Nov 26 2014

Upper flow will become more zonal for the end of the
week as weak ridging breaks down ahead of the next Pacific trough.
Warmer airmass over the region Friday will bring temperatures well above
seasonal averages. The next trough will cross the Pacific northwest
Saturday with strong cold front crossing the area. There is some
disagreement between the ecm/GFS with the timing of the front. The
GFS has trended warmer delaying the frontal passage till Saturday
night. The ecm continues to show the front passing during the day
Saturday. Have increased temperatures some to account for GFS...but
confidence is low at this time. Some light snow is possible Sat
night into possibly Sunday...but minimal quantitative precipitation forecast is expected. Colder air
will keep temperatures much colder early next week...but some modifying is
possible toward midweek.


Aviation...for the 12z tafs through 12z Thursday morning
issued at 249 am MST Wednesday Nov 26 2014

Snow will increase across the area today bringing
widespread MVFR/IFR conditions...and continue through tonight. Some
LIFR conditions expected near the Black Hills area.


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


Short term...10
long term...13

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