Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 191723

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1123 AM MDT Thu Apr 19 2018

.DISCUSSION...(Today Through Wednesday)
Issued at 320 AM MDT Thu Apr 19 2018

Current surface analysis shows high pressure centered over the
central Dakotas into eastern NE. Upper level analysis shows low
pressure over the southern Great Lakes region, with another low
digging southeast into CA. A ridge is in place between the two
systems across the Rockies and high plains. Skies are mostly clear
across the area, with scattered high clouds passing overhead, but
could see some patchy fog develop across parts of the SD plains
early this morning. Temps are mostly in the 30s with light winds.

Ridge will bring relatively nice weather and seasonable temps to
most areas today. However, south central SD will still see temps
below average with lingering snowpack. Southeasterly winds will
increase behind exiting high pressure, becoming breezy across
northeast WY and far western SD by the afternoon.

As ridge passes east of the area tonight, the storm system over the
southwest US will move east across the central/southern Rockies on
Friday and into the central/southern Plains during the early part of
the weekend. Models are in pretty good agreement on the track,
keeping the bulk of the pcpn south of the forecast area. However,
jet energy ahead of the system will push northward into the region
by Friday morning and bring some showers, especially across the
southern half of the CWA. The best chances look to be late Friday
morning into Friday night. The higher elevations of the Black hills
could see a mix or changeover to snow at times, especially into
Friday evening, but not expecting much if any accumulation. The
storm system is expected to turn southeast into the southern Plains
Saturday, with lingering pcpn shifting south and east of the CWA in
the morning. The rest of the weekend looks to be dry and mild with
highs in the upper 50s and 60s each day.

Another system is then projected to move east across the Northern
Rockies and into the Northern Plains early next week. Some
inconsistencies on the strength, timing, and track of the system
between the medium range models, but should see a good chance for
mostly rain showers sometime Monday through early Tuesday. Some snow
is possible Monday night across northeast WY and far western SD on
the back side of the system. A few thunderstorms are also possible
Monday afternoon/evening. Near or slightly below average
temperatures are generally expected Monday through Wednesday.


.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1120 AM MDT Thu Apr 19 2018

Ahead of a storm system, VFR conditions are expected through
tonight as clouds gradually increase and lower. Gusty southeast
winds are expected through this evening with gusts around 35kts
at times over northeast WY and far southwest SD. -SHRA will
develop Friday morning as the storm system spreads MVFR CIGS into
the region. -SHSN may occur at the highest elevations of the
Black Hills along with IFR conditions.




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