Area Forecast Discussion
Issued by NWS Rapid City, SD
FXUS63 KUNR 191540
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
940 AM MDT Wed Oct 19 2016
Issued at 930 AM MDT Wed Oct 19 2016
Upper level shortwave across eastern SD continues to shift east
with next shortwave approaching across central MT and WY. Brief
break in cloud cover across western SD this morning in between
these two systems. Cloud cover and scattered rain showers will be
on the increase late this morning and this afternoon across
northeast WY and western SD as shortwave slides across the area.
Guidance showing some very weak instability across the area this
afternoon, best across the Black Hills, so some isolated
thunderstorms will be possible.
Temperatures will be cool today, especially across northern
portions of the area, as a back door cool front slides south.
Current guidance not picking up on this, so have lowered high
temperatures across northwestern SD several degrees. Late in the
day, boundary will shift back north as upper shortwave passes
through, but will be too late in the day for temperatures to rise
.SHORT TERM...(Today Through Thursday Night)
Issued at 153 AM MDT Wed Oct 19 2016
Upper level wave is currently over the Rockies, pushing some
clouds into the CWA and rain into Nebraska. A west-east oriented
line of showers has developed along the cold front across western
and central SD. Satellite shows low clouds spreading southward
over ND, with some obs reporting fog...and so have added fog
across northwestern SD this morning. Winds are light and variable,
and temperatures at 2AM are in the 30s to lower 40s.
As main wave moves over the northern plains today, first embedded
shortwave over NE will push east. Most of the precip associated with
this one should stay to the south. A secondary embedded shortwave
and associated jet streak will then approach the CWA, bringing
increased chances of showers. A small amount of instability could
result in a few thunderstorms in the afternoon and early evening.
Highs will be in the 50s.
Temperatures will fall into the 30s tonight, and with showers still
moving across the area, rain may change to snow. Little to no
accumulations are expected, with the greatest chance of accumulating
snow over the Black Hills in the evening.
On Thursday, an upper ridge over the western CONUS will begin moving
eastward over the region, with mild and dry weather returning. Winds
will become southwesterly ahead of a low-level trough, and
temperatures will be in the upper 50s. Although the day will begin
mostly sunny, clouds will increase in the afternoon/evening as a
weak upper wave pushes through the ridge.
.LONG TERM...(Friday Through Tuesday)
Issued at 153 AM MDT Wed Oct 19 2016
Broad upper ridge will cover the cntrl conus through
early next week with an upper trof off the west coast gradually
pushing onshore. The result will be dry and mild conditions for the
region. SW flow aloft returns to the nrn plains by mid week as the
upper trof moves through the western conus. This may lead to
increasing chances for pcpn, although no significant storms are
expected at this time.
.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 153 AM MDT Wed Oct 19 2016
Showers are possible this morning mainly across
southern SD where local MVFR ceilings are possible. There is a
better chance of showers across the area this afternoon and evening,
with isolated thunderstorms from the Black Hills into southwest
South Dakota. MVFR conditions expected with the precipitation.
MVFR stratus may move into northwest SD this morning, then spread
through the SD plains late this afternoon and tonight.