Area Forecast Discussion
Issued by NWS Rapid City, SD
FXUS63 KUNR 161716
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1116 AM MDT Sun Oct 16 2016
.SHORT TERM...(Today Through Monday Night)
Issued at 311 AM MDT Sun Oct 16 2016
Upper level analysis shows west-southwest flow over the northern
plains, with a 90 kt jet moving over the region. Skies are
becoming mostly cloudy as mid/high clouds move in. Radar is
picking up on a few echoes across northeastern WY, but doubt
anything is reaching the ground with dry low levels. Winds are
southerly ahead of approaching surface trough, and temperatures at
3AM are in the 50s.
Pressure gradient will increase ahead of surface trough today, and
winds will become gusty across the CWA. Early this morning, model
soundings are showing 40-50 kt winds just above the surface. The
potential exists for some 50kt gusts to mix down, especially across
downsloped northeastern foothills and the Pine Ridge area. However,
models differ on timing...with some showing gusts this morning and
others this afternoon. Current thinking is that inversion will
prevent strongest gusts from mixing down this morning...and winds
aloft should decrease a bit by the time of peak mixing. Confidence
is low, so may need to reassess early this morning.
Nonetheless...a gusty day is expected.
The gusty southwest winds will advect in warm and dry air.
Temperatures on the plains will be well into the 80s, assuming cloud
cover doesn`t hinder highs. A cool front will pass through the CWA
this afternoon, keeping highs in the 60s over the Hills and the 70s
across northeastern WY and northwestern SD. Winds will diminish this
evening. Next upper shortwave approaches the region tonight,
bringing some light rain showers to northeastern WY by early
morning. Lows will be mainly in the 40s.
Showers will continue Monday as wave crosses the region, mainly over
northeastern WY, the Black Hills, and northwestern SD. Westerly
winds will become strong across the southern CWA as surface low
passes through the northern plains and with a 140 kt jet overhead.
Another cold front will also move through behind the trough. NAM is
showing 5 mb/3hr pressure rises over the area in the
afternoon...increasing to 9 mb/3hr by 00Z across south central SD.
Increased winds across the southern CWA. Precip will gradually
diminish...and lows will be in the mid 30s to mid 40s.
.LONG TERM...(Tuesday Through Saturday)
Issued at 311 AM MDT Sun Oct 16 2016
Behind the aforementioned cold front, cooler weather is
expected Tuesday through Thursday. Moisture will be limited, but
there could be a few spotty light showers as an upper level trough
moves through Wednesday. 00z NAM most aggressive with this feature
Tuesday night. Latest long term model trend is for a stronger upper
ridge for the end of next week into next weekend, which will result
in a warming trend.
.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1106 AM MDT Sun Oct 16 2016
Gusty winds will continue into the early evening, gradually
diminishing through the rest of the evening. There is a chance of
showers over northeastern Wyoming and the Black Hills after 06Z
tonight, increasing in coverage and spreading into northwestern
south dakota after 12Z Monday morning. LCL IFR conditions will be
possible over parts of south central South Dakota between 14Z and
18Z monday, otherwise VFR conditions are expected.
Issued At 1114 AM MDT Sun Oct 16 2016
Another warm and dry day is expected today. Highs
will range from the lower to mid 70s across northeastern WY to
the upper 80s across central SD, with min RH values near 15%.
Gusty southwest winds of 20-30 mph with gusts around 45 mph are
occurring, so critical fire weather conditions are expected this
afternoon. The Red Flag Warning continues.
SD...Red Flag Warning until 6 PM MDT this evening for SDZ261-263>266.
WY...Red Flag Warning until 6 PM MDT this evening for WYZ259-297-298.