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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
536 am MDT Tuesday Oct 6 2015

Short through Wednesday night
issued at 305 am MDT Tuesday Oct 6 2015

Current surface analysis shows weak frontal boundary remaining
across southern South Dakota into Wyoming...with high pressure centered over
southwest sk. Upper level analysis shows low over southeast
California...with southwest flow stretching out across the southern
rockies and into the Central High plains. Northern stream flow set
up to the north from the Canadian rockies and across most of the
northern plains. Sat imagery shows breaks in the clouds across
northeast Wyoming and much of western South Dakota as some drier air moves in
from the northwest behind the boundary...with mainly cloudy
conditions persisting toward south central South Dakota. Patchy fog is
developing where clouds have broken up. Temperatures are in the 40s
across northeast Wyoming...the Black Hills...and northwest South Dakota...with
50s across much of southwest and south central South Dakota. Winds are
mostly light and variable.

Milder weather will continue to build into the area over the next
couple of days...with above average temperatures on Wednesday. Short range
models continue to diminish the chances for rainfall for most of the
County Warning Area over the next couple of days as the area will be mostly cut off
from energy rotating out of southwest Continental U.S. System. Best chances
will likely be toward central South Dakota late Wednesday as northern stream
shortwave and cold front clip the area.

For today...skies will be variably cloudy this morning with patchy
fog early on. Some sun can be expected in most areas...especially
northern and western portions of the County Warning Area. However...skies will
become mostly cloudy in the afternoon across northeast Wyoming and
southwest South Dakota as a piece of energy moves northeast across Wyoming from The
Rockies. Will keep a slight chance for showers and thunderstorms
over southern portions of northeast Wyoming into the Black Hills and far
southwest South Dakota later this afternoon. Highs will generally be in the
60s with light and variable winds becoming southeasterly in most
areas during the midday and afternoon hours. Will keep slight
chances for showers and thunderstorms into tonight across southwest
South Dakota as left over energy moves across that area and weak low level jet
develops over the Nebraska Panhandle. Lows will be in the middle 40s to
middle 50s.

Wednesday looks to be the warmest day of the week for most areas as
boundary moves east of the region as a warm front. Highs will be in
the 70s across the plains...with 60s over the higher Black Hills.
Any chances for showers and storms will mostly be in the afternoon
and evening to the east of the Black Hills...especially toward
central South shortwave energy and cold front sweep through. Would
not be surprised to see a stronger storm develop over south central
South Dakota...where ample low level moisture and instability are prognosticated
later in the afternoon and early evening. A couple of the models are
now showing again some Post frontal shortwave energy moving across
northeast Wyoming and western South Dakota later Wednesday night...but in general
the models have been very inconsistent with this feature. Will leave
pop chances out for now...but they may very well need to be added in
future forecasts if the 00z trends persist.

Long term...Thursday through Monday
issued at 305 am MDT Tuesday Oct 6 2015

Very weak high pressure Thursday will bring slightly cooler
temperatures. An upper level ridge will then build into the County Warning Area
through early next week. A couple of shortwaves will clip the
area...but moisture will be limited with main frontal forcing
north of the County Warning Area. Will maintain dry forecast. Temperatures will be
well above normal.


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 535 am MDT Tuesday Oct 6 2015

Moist boundary layer will promote local IFR/LIFR visibilities due to
br/fog this morning. Br/fog will burn off by midday as robust
boundary layer mixing takes shape. Areas MVFR ceilings/local IFR ceilings due
to St/SC will becoming VFR this afternoon with these conditions
persisting through tonight.


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


Short term...26
long term...helgeson

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