Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 161719

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1119 AM MDT Thu Aug 16 2018

.DISCUSSION...(Today Through Wednesday)
Issued at 403 AM MDT Thu Aug 16 2018

Current upper level analysis has compact closed low over southeast
South Dakota with large ridge building across the Northern
Rockies. Skies are mostly clear across Northeast Wyoming and
western South Dakota, with some lingering clouds across far south
central South Dakota. At the surface, high pressure is located
across Montana, Wyoming, and the Dakotas. Winds are light, and
temperatures at 4 am are in the 50s to lower 60s.

Upper ridge will slowly shift across the Northern Plains today and
Friday. Dry conditions and near average temperatures are expected.

A progressive upper trof will move across the Northern Plains for
the weekend. Moisture return begins in earnest Friday night as
boundary layer winds become southerly ahead of the system. As the
surface trof and mid level low shifts into western SD mid day
Saturday, CAPE values of 1500-2500 J/kg and modest shear should
produce some strong to severe storms across the South Dakota
plains through early evening. Rain and isolated thunderstorms will
persist into Sunday morning before shifting east of the area
Sunday afternoon and evening.

Early next week, west to northwest flow may bring some low
chances of precipitation at times, but mostly dry conditions
should prevail. The week will start off with slightly below
average temperatures, and warm to near average by mid week.


.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1118 AM MDT Thu Aug 16 2018

VFR conditions are expected through the period.




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