Area Forecast Discussion
Issued by NWS Rapid City, SD

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450
FXUS63 KUNR 211050
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
450 AM MDT Wed Jun 21 2017

.DISCUSSION...(Today Through Tuesday)
Issued at 248 AM MDT Wed Jun 21 2017

Upper level analysis has broad but flat ridge across the western
CONUS with fast zonal flow across the Pacific Northwest through
the northern Plains. Showers and thunderstorms moving east across
central and western SD at the moment. At the surface, cold front
extends from southern Canada through central Montana, with weak
warm front lifting through western SD. Temperatures at 3 am are in
the 60s, with light and variable winds.

Today...Western upper ridge will continue to flatten as strong
upper shortwave moves across southern Canada. Cold front over
Montana will move into western portions of the area this morning
before stalling out over western SD during the day. Behind the
front, northwest winds will be breezy across northwest and west
central SD. Highs will range from the lower to mid 80s over
northeast WY and the Black Hills, to near 95 over south central
SD. A thunderstorm or two is possible over the Black Hills area
late in the afternoon and early evening. Another round of
nocturnal convection is possible later tonight as a weak
disturbance aloft passes across and eventually pushes the cold
front east of the forecast area. Isolated strong to severe storms
are possible near and east of the front from southwest to central
SD late tonight.

Thursday...On going showers and thunderstorms will be possible
Thursday morning across the South Dakota plains before finally
shifting east mid day. Cooler air will move into the area during
the morning, with highs Thursday afternoon in the 70s.

Friday into the weekend...Broad upper trof will settle across the
northern CONUS, with Friday and Saturday being the coolest days.
Highs will only be in the 60s to lower 70s. An upper shortwave
and Canadian cold front will slide southeast through the area late
Friday into Saturday morning, bringing a chance of showers and a
few storms. Mainly dry weather and warmer air will return late in
the weekend and early next week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 448 AM MDT Wed Jun 21 2017

VFR conditions will be found across the area today. A period of
gusty northwest winds are expected this morning through midday as
a cold front moves through the area. A few thunderstorms may
develop tonight, with local MVFR conditions.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION...15
AVIATION...7



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