Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 111548

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
848 AM MST Wed Jan 11 2017

Issued at 848 AM MST Wed Jan 11 2017

Current surface analysis shows arctic front south of the cwa, with
high pressure centered over northern MT. Upper level analysis
shows low southwest of Hudson Bay, with another low over the
Pacific NW. Near zonal flow over the northern and central plains
is bringing weak energy across the region. Lots of clouds and
patchy areas of light snow right now. Temps are mostly around
zero or in the single digits, with wind chills around 20 below
across far northwest SD. Will plan on expiring the wind chill
advisory for far northwest SD late this morning.

There will be a bit of a break in snow late this morning before
another band of snow slides east across portions of the region
this afternoon and evening. Short range models generally agree on
this next band of snow being more focused across far southern SD
and northern Neb. Snowfall amounts up to 2 inches are expected
across much of southern SD this afternoon and evening, with
localized 3 inch amounts possible toward south central SD. Have
updated grids to adjust pops and snowfall amounts based on latest
guidance. Temps will not rise much through the rest of today, with
highs in the single digits and lower teens.


.SHORT TERM...(Today Through Thursday Night)
Issued at 213 AM MST Wed Jan 11 2017

Current surface map shows arctic front surging southward south of
the forecast area. A few locations in northeast Wyoming and
northwest South Dakota have dropped below zero with wind chills
around 20 below zero. Jet steak providing some forcing along mid
level baroclinic zone resulting in area of snow across northeast
Wyoming into western South Dakota. Band of snow expected to shift
southward and weaken this morning. Weak forcing will continue
across southern half of forecast area through this evening.
1020+mb high settles in across the central Dakotas tonight with
most locations dropping below zero. Dry weather expected on
Thursday as core of arctic air shifts east. Warmest temperatures
will be in the higher elevations of the Black Hills.

.LONG TERM...(Friday Through Tuesday)
Issued at 213 AM MST Wed Jan 11 2017

By Friday, weak upper ridging will develop over the
northwestern CONUS, and the Canadian low pressure systems will shift
eastward, along with the arctic airmass. This will initiate a
gradual warming trend through early next week, with temperatures
returning to near average values (mid 30s) Sunday into Monday. Dry
weather is also expected through the weekend. An upper low will
track under the ridge across the central plains on Monday. Latest
GFS track is aligning more with the EC, although a bit slower, and
the GFS/EC/GEM all show precip barely making it into south central
SD. Elsewhere, dry weather will continue, along with near to above
average temperatures through the middle of next week.


.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 213 AM MST Wed Jan 11 2017

MVFR/IFR conditions in light snow will continue over much
of the area through this evening, with better ceilings/visibility
across northwestern SD. Conditions will gradually improve to VFR
after midnight.


SD...Wind Chill Advisory until noon MST today for SDZ001-002.



LONG TERM...Pojorlie
AVIATION...Pojorlie is the U.S. government's official web portal to all federal, state and local government web resources and services.