Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 171727
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1127 AM MDT Fri Mar 17 2017

.SHORT TERM...(Today Through Saturday Night)
Issued at 218 AM MDT Fri Mar 17 2017

Sfc ridge will continue to build into the region today with
ongoing pressure rises and faster BL flow supporting breezy winds
on the NW SD plains. After a few lingering early morning showers,
dry weather can be expected. The next system will push into the
PAC NW and support shortwave ridging into the region Sat. WAA per
downslope Rockies flow will support much warmer conds most places.
However, ongoing pressure falls will support SE flow over most of
western SD and will fight the breakdown of the growing temp
inversion aloft, slowing warming to a degree. Hence, expect a
range of highs from lower 60s east to the upper 70s west (warmest
where flow turns SW, likely NE WY and far SW SD). Lee side trough
will shift east overnight Sat, supporting very mild temps, esp in
the lee of the Black Hills where downward flow transport will
continue to mix down warm air aloft.

.LONG TERM...(Sunday Through Thursday)
Issued at 218 AM MDT Fri Mar 17 2017

Cold front will shift south into the FA Sunday, with northern
areas seeing much cooler temps, while scentral SD will see highs
in the upper 70s. Post frontal impulse with a stalling ll boundary
and diurnal heating will support sct/isold showers/thunderstorms
Sunday afternoon, NE WY and far western SD. Shower chances will
linger and spread east Sunday night with CAA ongoing.

Flow will remain progressive, but will become more amplified next
week, supporting deeper/stronger troughs into the CONUS per
active northern PAC flow. Unsettled and near seasonal to slightly
above seasonal temps expected much of next week, with periodic
chances for rain and snow showers and breezy conds. ECMWF/GFS
progs continue to suggest a stronger system will affect the region
toward Thur-Fri next week, with perhaps appreciable precip for a
portion of the FA, esp if the upper trough trends NW. Warm thermal
fields continue suggest mainly rain with this system.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1126 AM MDT Fri Mar 17 2017

VFR conditions will continue through the period. Gusty northwest
winds on the SD plains will subside this evening. Gusty southerly
winds will develop over the northeast WY plains overnight.

&&

.FIRE WEATHER...
Issued At 218 AM MDT Fri Mar 17 2017

Warm dry westerly flow will support critical to near critical fire
weather conditions Saturday afternoon over portions of NE WY. RH
is expected to drop to 10-15 percent. Winds will be the deciding
factor with current progs suggesting 20-30 mph winds should
develop as long as deeper mixing results. Have decided to issue a
fire weather watch for all of Campbell county where the strongest
winds and deepest mixing are expected.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...Fire Weather Watch Saturday afternoon for WYZ259-297.

&&

$$

SHORT TERM...JC
LONG TERM...JC
AVIATION...Helgeson
FIRE WEATHER...JC



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