Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 282101

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
301 PM MDT Fri Apr 28 2017

.DISCUSSION...(This Evening Through Friday)
Issued at 300 PM MDT Fri Apr 28 2017

Current surface analysis shows low pressure now over eastern CO,
with dry high pressure over ND. Upper level analysis shows broad
upper trough covering the western and central US, with low
pressure within it sinking south across eastern UT and western CO.
Strong upper jet wraps around the low from the Pacific NW to the
Southern Plains. KUDX and regional radars show lingering areas of
light snow across Campbell County, with patchy light rain or snow
stretching southeast into far southwest SD. Current temps range
from the 30s across parts of northeast WY and the Black Hills to
near 50 across far northwest SD where there is some sunshine.
Winds are mostly from the northeast at 10 to 20 mph.

Snowfall amounts were highly variable across northeast WY and
southwest SD. The highest totals were in the Gillette area and
across parts of southern Campbell County, where 6+ inches were
reported, with around 12 inches in parts of the Gillette area.
Localized areas of southern Weston County, the southern Black Hills,
and Fall River County also saw close to 6 inches of snow. Otherwise,
up to a few inches of snow was reported elsewhere from Campbell
County to the Black Hills and far southwest SD.

Upper level low will continue to sink south to the Four Corners area
tonight, with remaining pcpn sliding south and west out of the area
with it by this evening. Have cancelled remaining warning and
advisory for Campbell County as little or no additional accumulation
is expected. Skies will stay mostly cloudy across much of the area
this evening, with some breaks in the clouds overnight. Patchy fog
looks possible late tonight into early Saturday across at least
northeast WY and southwest SD as RH`s approach 100 percent in some
areas with light winds in place. Lows will be in the 20s across
most areas.

The weekend looks to be dry in most areas with a warming trend.
Highs will be in the 40s to mid 50s Saturday, coolest over snow
covered areas of northeast WY, with 50s to around 60 on Sunday. The
upper low to the southwest of the region will eject out into the
Southern Plains late Saturday and then track northeast into the
upper MS river valley Sunday into Monday. Still looks like the
northwest edge of the pcpn shield could clip far south central SD
Saturday night through Sunday night, so will keep some lower pops

The first half of next week looks unsettled as northwest flow on the
back side of eastward moving upper trough brings a series of weaker
disturbances across the Northern Plains. Daily chances for showers
are expected in many areas, mostly during the afternoon and evening
hours. A few thunderstorms also look possible Monday afternoon.
Temperatures will remain slightly below average through Wednesday,
with highs mostly in the 50s and lower 60s. Ridging is still
forecast to build into the region late in the week, with highs
rising to the 60s and 70s on Thursday and Friday, Friday being the
warmer day for most areas.


.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1108 AM MDT Fri Apr 28 2017

Area of snow across northeastern Wyoming, the Black Hills area
and southwestern South Dakota will dissipate this afternoon.
Widespread IFR conditions expected with the snow. As the snow
ends, MVFR ceilings will remain across this area. The MVFR
ceilings will gradually improve to VFR by late evening. VFR
conditions expected through the period for the remainder of
western/northwestern South Dakota.




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