Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 192325

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
525 PM MDT Thu Apr 19 2018

.DISCUSSION...(This Evening Through Thursday)
Issued at 153 PM MDT Thu Apr 19 2018

Upper level analysis shows a ridge over the central CONUS, with
low pressure spinning over central Nevada. Some cirrus clouds are
streaming into the region from the southwest. Southeasterly winds
are becoming breezy between a surface high to the east and low to
the southwest. Temperatures are rising into the 50s.

Upper low will shift over the Four Corners region tonight. Rain will
begin spreading across the CWA early Friday morning, with some light
snow possible over the Hills. ECMWF and GFS have somewhat met in the
middle with their precip predictions, agreeing that the likeliest
chance for rain will be across the southern half of the CWA.

Precip will end early Saturday, as the low transitions
southeastward. Brief upper ridging will allow for a warm and dry
weekend, with highs in the 50s and 60s.

On Monday, a potent shortwave will dive into the northern plains.
The GFS and ECMWF are in better agreement about rain showers holding
off until the afternoon, whereas the Canadian is earlier. Some weak
instability may allow for a few isolated thunderstorms. Following
this wave, a more benign weather pattern is expected to bring a mild
and fairly dry rest of the week.


.AVIATION...(For the 00Z TAFS Through 00Z Friday Evening)
Issued At 525 PM MDT Thu Apr 19 2018

VFR conditions will continue through the early overnight period.
Later tonight into Friday morning, cigs will gradually lower to
MVFR from southwest to northeast as SHRA approach the area.
Widespread MVFR cigs are then expected through Friday evening. IFR
cigs/vsbys are possible over higher elevations of the Black Hills,
where SHSN are expected.

Low-level wind shear may develop across portions of northeastern
WY from 03-09z as a low-level jet ramps up in advance of the
approaching disturbance. However, for now, expecting near-surface
winds to remain strong and gusty across this area overnight, so
shear will likely remain below criteria.




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