Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 200436

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1036 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 06Z TAFS Through 06Z Friday Night)
Issued At 1036 PM MDT Thu Apr 19 2018

VFR conditions are now expected to persist area-wide through
approximately 15z Friday.

After 15z, MVFR cigs associated with SHRA will develop over
northeastern WY/southwestern SD, then gradually overspread most of
the area Friday afternoon into the evening. Over higher elevations
of the Black Hills, IFR/LIFR cigs and vsbys are expected in -SHSN.
Occasional IFR/LIFR cigs are also possible in heavier SHRA across
northeast WY and far western SD.

Once MVFR to LIFR conditions develop tomorrow morning/afternoon,
they should hold for the remainder of the TAF period.




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