Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 141124

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
524 AM MDT Mon May 14 2018

.DISCUSSION...(Today Through Sunday)
Issued at 218 AM MDT Mon May 14 2018

Upper low centered over the Great Basin will support another
round of ISOLD/SCT shra/ts across the region today as a large
portion of the trough ejects east into the plains. Best chance for
activity will be over the Black Hills and portions of southern NE
WY where better instability will be found. Otherwise, more
isolated activity is expected on the SD plains, esp NW SD. Mean
CAPE progs top out around 700-800 J/KG this afternoon from the BH
south, suggesting an almost nil severe threat when couple with
poor deep layer bulk shear values. Small hail and gusty winds
would be possible with any storms. Warmer weather can be expected
with most places seeing 60s and 70s for highs today. A warming
trend is forecast Tue-Thur as shortwave ridging occurs ahead of
the next western CONUS trough. Unsettled SW flow will remain
through, supporting low chances for shra/ts Tue and esp Wed, best
around the BH. Strong northern stream trough will force a cold
front into the region Thurs, supporting better chances for storms
with better/deeper moisture expected. This will support increased
chances for severe weather given expected CAPE values of 1-2
KJ/KG. However, deep layer shear still looks limited, with current
progs around 30 knots or less. Rain chances will linger through
Friday as the western CONUS trough shifts east into the Plains,
supporting unsettled cyclonic flow aloft. Much cooler weather
still on track for the weekend, with highs in the 40s and 50s
likely for much of the area by Sat. Warmer but still unsettled
weather is looking likely into early next week as another round of
western CONUS troughing is favored in deterministic models attm.


.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 524 AM MDT Mon May 14 2018

Areas of MVFR/IFR conditions will persist across the area early
this morning, with patchy fog/LIFR conditions from northeast WY to
southern SD. Isolated to scattered showers and thunderstorms will
develop late this morning and afternoon, with the most coverage
expected from southern parts of northeast WY to southwest SD.
Showers will end this evening, with clearing skies and general VFR
conditions expected overnight. Patchy fog could develop late
tonight/early Tuesday in valley locations.




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