Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 191520

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
920 AM MDT TUE JUL 19 2016

Issued at 915 AM MDT Tue Jul 19 2016

small update to add low pops for diurnal convection, mainly off
the high terrain. Deep mixing should support isold high based
shra/ts, mainly WY and the BH/s area late this afternoon. lack of
sufficient cape will highly limit severe threat, although deeply
mixed inverted V soundings will support a gusty wind threat.


.SHORT TERM...(Today Through Wednesday Night)
Issued at 326 AM MDT Tue Jul 19 2016

Water vapor shows upper ridge amplifying through the nrn plains.
At the sfc...low is centered over sern MT with trof extending sewd
into scntrl SD. Convection has pushed well south/east of the cwfa.

Today...thermal ridge will build into our wrn zones with temps
rising well into the 90s through the cwfa...and even lower 100s on
the plains south/east of the blkhls. Heat indicies will push over
100 across cntrl SD...and have upgraded the excessive heat watch
to a warning as several days of heat indicies over 100 are
expected. An upper wave will approach swrn/scntrl sd this
aftn/eve and should provide the lift necessary for a few storms to
develop...especially along the sfc boundary in place from the
blkhls through scntrl SD. Mlcape will be in the 1500-2500j/kg
range...with best shear for a few strong/svr storms over scntrl
SD. Storms should end by midnight.

Wednesday...Hot and dry conditions expected. Thermal ridge will
be centered over wrn SD and should result in the hottest day of
the week. Most areas outside of the blkhls should reach or exceed
100...with heat indicies possibly as high as 110 over scntrl SD.

.LONG TERM...(Thursday Through Monday)
Issued at 326 AM MDT Tue Jul 19 2016

Latest medium range guidance has upper level ridge
flattening a bit by Thursday as a weak shortwave races across
southern Canada. 850mb temps on Thursday suggest a weak back-door
front drops into the SD plains, possibly cooling high temps a few
degrees. Upper ridge breaks down even further by Friday and the
weekend as a shortwave over the Pacific NW moves into the Northern
Plains. This will result in near zonal flow and temperatures being
close to seasonable normals by the weekend, with increasing chances
of showers and thunderstorms.


.AVIATION...(For the 12Z TAFS Through 12Z Wednesday Morning)
Issued At 326 AM MDT Tue Jul 19 2016

VFR conditions are expected through the forecast period.
The exception will be a chance of showers and thunderstorms from the
Black Hills through south central SD late this afternoon and


.UNR Watches/Warnings/Advisories...
SD...Excessive Heat Warning until 6 PM MDT /7 PM CDT/ Friday for



SHORT TERM...Johnson
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