Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 201731
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1131 AM MDT WED JUL 20 2016

.SHORT TERM...(Today Through Thursday Night)
Issued at 229 AM MDT Wed Jul 20 2016

Water vapor shows upper ridge over the nrn plains/upper midwest.
At the sfc...broad low pressure covers the nrn plains. Some radar
returns over sern MT/swrn ND at srn end of short wave over far
nern MT/srn SASK...but most of this likely not reaching the
ground.

Today...very hot conditions expected as thermal ridge peaks over
wrn SD. Deep mixing and temp profiles suggest temps near 100 over
nern WY and well into the 90s in the Blkhls. Readings of 105 to
110 expected on the plains east of the Blkhls. Have added most wrn
SD zones to the heat advisory given expected heat indicies near
100 even into the foothills. No changes to the excessive heat
warning. Could see a storm or two late this aftn/evening over far
nwrn SD as cdfnt approaches...and maybe a storm over the terrain
of the Blkhls. Cdfnt will then work sewd through the cwfa tonight.

Thursday...N/NE boundary layer flow behind the cdfnt will usher
slightly cooler air through the cwfa. Will leave the excessive
heat warning in place for now...but it`s possible some zones may
need to be cancelled early. Other than an isold storm or two in
the Blkhls...pcpn chances should remain minimal.

.LONG TERM...(Friday Through Tuesday)
Issued at 229 AM MDT Wed Jul 20 2016

Central CONUS upper ridge breaks down a little more by Friday and
over the weekend as an upper low moves across southern Canada.
This will result in near zonal flow and temperatures in the 90s to
around 100 degrees. By the weekend, upper low shifts to the east,
with low chances of precip returning to the area. Temperatures
will cool further, in the 80s to lower 90s. Temperatures remain
near seasonal averages early next week, with low chances for
showers and thunderstorms continuing.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Thursday)
Issued At 1130 AM MDT Wed Jul 20 2016

An isolated thunderstorm will be possible late this afternoon and
early evening, and could produce brief MVFR cigs/vis. Otherwise
VFR conditions are expected through the forecast period.

&&

.FIRE WEATHER...
Issued At 229 AM MDT Wed Jul 20 2016

Although relative humidities will be critically low
today...expected wind speeds not strong enough to pull the trigger
on a red flag warning over nern WY. However...Some gusts of 20 to
25 mph possible during the aftn given how deeply mixed the
atmosphere will become.

&&

.UNR Watches/Warnings/Advisories...
SD...Excessive Heat Warning until 6 PM MDT /7 PM CDT/ Friday for
     SDZ014-032-043-044-046-047-049.

     Heat Advisory until 7 PM MDT this evening for SDZ001-002-012-013-
     026-027-030-031-041-042-072>074.

WY...None.
&&

$$

SHORT TERM...Johnson
LONG TERM...15
AVIATION...McKemy
FIRE WEATHER...Johnson


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