Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 242100

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
300 PM MDT Thu May 24 2018

.DISCUSSION...(This Evening Through Thursday)
Issued at 236 PM MDT Thu May 24 2018

A look aloft this afternoon shows an upper trough extending from
eastern North Dakota to south central south Dakota and southward
into Nebraska which is mirrored by the location of the surface
trough. Weak mid-level CAA is depicted by a field of relatively
flat CU moving eastward across northeastern Wyoming and western
South Dakota this afternoon. MLCAPE remains relatively low over
most of the area with the exception being east of the sfc trough
over the eastern parts of Mellette and Todd and also over Tripp
counties in south central South Dakota. East of the sfc trough the
MLCAPE has risen to 1000-2000J/KG. May see some strong thunderstorms
develop in that area during the late afternoon and moving east of
our forecast area during the early evening.

An upper ridge will build over the Rockies Friday, before moving
eastward into the high plains on Saturday. Expect the thermal
ridge to be centered over the forecast area on Saturday which
will bring very warm temperatures. Diurnal heating may also allow
for an isolated afternoon thunderstorm to develop over the higher
terrain of northeastern Wyoming or the Black Hills.

The ridge shifts east on Sunday as an upper low strengthens over the
Great Basin area. Moisture will increase as the upper trough/low
begins to affect the northern Plains. This will bring a period of
active weather with good chances for thunderstorms Sunday through
Tuesday. Near daily chances for thunderstorms will continue
through much of next week.


.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1121 AM MDT Thu May 24 2018

VFR conditions expected through Friday morning. The exception will
be isolated thunderstorms over the Black Hills area, NW WY and
scentral SD this afternoon and evening.




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