Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 150910

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
310 AM MDT Sun Apr 15 2018

.DISCUSSION...(Today Through Saturday)
Issued at 310 AM MDT Sun Apr 15 2018

Current surface analysis shows low pressure over the MS river
valley, with arctic boundary over eastern portions of MT, WY, and
the lee of the Rockies. Upper level analysis shows low pressure
slowly moving east across southern IA, with ridge over the
Rockies. Skies are mainly clear across the area with light winds.
Temps range from the teens over the SD plains to around 30 in
northeast WY.

Warming trend will continue over the next couple of days, especially
across northeast WY and the Black Hills, as ridge shifts east over
the Plains. Temperatures will remain on the cool side across snow
covered areas of SD. Highs today will range from the 30s to around
40 across much of the SD plains to around 60 in Campbell County WY.
Winds will become southeasterly in most areas by the afternoon,
breezy across northeast WY. Highs on Monday will be about 10 degrees
warmer in most areas, though heavily snow covered areas toward south
central SD could remain in the 30s. Breezy to windy south to
southeast winds will develop by the afternoon, ahead of low pressure
moving across MT.

The next system will arrive behind exiting ridge later Monday night
and Tuesday morning. Shortwave will move across the northern Rockies
and into the Northern Plains, along with a cold front moving through
on Tuesday. Areas of rain will develop, with colder air eventually
changing pcpn over to snow later Tuesday and Tuesday night. The
system is progged to intensify as it moves east of the region
Tuesday night, with some enhanced areas of pcpn toward central SD on
the back side. Any snow accumulations look relatively light at this
point, but there is potential for up to a few inches of snowfall
across the Black Hills, as well as parts of south central SD. Brisk
northwesterly winds will develop behind the front.

A shortwave ridge behind exiting system will bring a period of
mainly dry weather from Wednesday afternoon through the day on
Thursday. However, temperatures will remain below average mid to
late week. Yet another strong system will move across the western US
late in the week, this one further south than previous systems. At
this point, it looks like it will track mostly south of our area,
but at least the northern fringes of the system could bring some
rain and snow Friday and Friday night, especially to southern SD.
There has been a good amount of model inconsistency regarding this
system, so will continue to watch it over the coming days.


.AVIATION...(For the 06Z TAFS Through 06Z Sunday Night)
Issued At 934 PM MDT Sat Apr 14 2018

VFR conditions expected through Sunday.




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