Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 282034
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
234 PM MDT THU JUL 28 2016

.SHORT TERM...(This Evening Through Friday Night)
Issued at 231 PM MDT Thu Jul 28 2016

20z surface analysis had old frontal boundary from western WY
into northeast CO with trough into southeast MT where a weak low
was located. This weak low was associated with a shortwave over
northeast WY, which is assisting round of convection over the CWA
this afternoon. Next wave upstream appears to be over south
central MT, which should push through the CWA late this afternoon
and early this evening supporting continued SHRA/TSRA. MLCAPE
averaging 500-750J/kg over CWA with weak 0-6km bulk shear.
Activity will wane some with sunset, but given energy upstream
some precipitation expected overnight. Temperatures will be
pleasantly cool.

Friday, upper ridge over the southwest US will slowly push toward
the northern plains, but northwest flow aloft will support a couple
of weak waves moving through with modest MLCAPE values by afternoon.
Leftover boundaries from tonight combined with diurnal insolation
will result in continue TSRA chances by afternoon, but activity
should be less widespread than today. Temperatures will be near
guidance.

Friday night, precipitation will be on the wane as ridging increases
and drier air begins to work into the area.

.LONG TERM...(Saturday Through Thursday)
Issued at 231 PM MDT Thu Jul 28 2016

Weak upper level ridge slides across the northern plains this
weekend as upper low moves into southwestern Canada. With marginal
instability, there is a small threat for isolated thunderstorms.
Temperatures will warm back into the 90s for the weekend. Upper
low continues to move eastward across southern Canada early next
week, with increasing west-southwest mid level flow across the
northern plains. Series of weak impulses will bring a daily chance
of isolated thunderstorms. Temperatures will be cooler, but still
above average by the middle of the week.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 231 PM MDT Thu Jul 28 2016

Scattered showers and thunderstorms will continue across
northeast Wyoming and western South Dakota through the evening
hours. Areas of MVFR ceilings and visibility expected with the
precipitation. Mainly VFR conditions expected after midnight into
Friday morning.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...Helgeson
LONG TERM...15
AVIATION...15


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