Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 302058

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
258 PM MDT Thu Mar 30 2017

.SHORT TERM...(This Evening Through Friday Night)
Issued at 258 PM MDT Thu Mar 30 2017

Current surface analysis shows low pressure over southern SK,
with cold front trailing southwest into the Pacific NW. Upper
level analysis shows slow moving low across western MO, with next
trough across the western states. West-southwest flow ahead of the
trough has brought increasing clouds and now a few showers across
northeast WY. Temps are in the upper 40s and 50s with south to
southeast winds.

Unsettled weather can be expected through the period as the trough
to the west moves east across the Rockies and Plains through
Saturday. The shorter range models are in decent agreement on
general track, but differ some on timing and cutoff of general pcpn
across the area. EC is a bit further south and faster than the NAM
and GFS, with EC showing little or no rainfall to the north and east
of the Black Hills. GFS and NAM show at least some lighter rainfall
extending up into southern parts of northwest SD and also into south
central SD, with more significant pcpn across parts of northeast WY
into southwest SD. Will lean forecast more toward the wetter GFS for
now, but will likely not see the higher QPF that it is showing in
most areas.

The better chances for pcpn across northeast WY and far southwest SD
should be later tonight into Friday as the main shortwave wraps up
into these areas, with better chances further to the north and east
across the CWA later Friday into Friday night if secondary energy
makes it that far. Some wet snow could develop late tonight/Friday
morning over the highest elevations of northeast WY and the Black
Hills. The same is true across these areas Friday night as the
system begins to move away. Lows tonight will be 30s to around 40
degrees, with highs in the 40s to mid 50s on Friday, warmest over
far northwest SD.

.LONG TERM...(Saturday Through Thursday)
Issued at 258 PM MDT Thu Mar 30 2017

The storm system will slowly move across the Plains and weaken on
Saturday, with any lingering pcpn ending across southern portions
of the CWA. Dry conditions are then generally expected through
the day Sunday, though a few showers could develop across
northeast WY on Sunday as a weak shortwave clips the area. Highs
on Saturday will mostly be in the 50s, with some 60s across the SD
plains on Sunday.

The next upper level system will begin to impact the area by Monday
morning. This system looks to be more significant than the last
couple at this point, but still some large differences between the
various medium range models with regard to strength, timing, and
track. This system is still projected to take a more northerly track
across the region, so the better chances for pcpn would be more
widespread, with more significant pcpn possible in at least some
areas. Still looks warm enough for mostly rain, at least for Monday
into Monday night, with some mix or change over to snow certainly
possible across the higher elevations of the western CWA, especially
the Black Hills. Lots of uncertainty at this point and most of the
latest runs have trended at least a bit weaker, so will have to
closely monitor over the next few days.


.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 258 PM MDT Thu Mar 30 2017

Showers will continue to develop across northeast WY this
afternoon and move east into the Black Hills area and far western
SD late today and tonight. Areas of MVFR/IFR conditions can be
expected. Some wet snow could mix in across the higher Black Hills
overnight/Friday morning. Patchy fog is possible along the
eastern slopes of the Black Hills to south central SD late
tonight/early Friday.




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