Area Forecast Discussion
Issued by NWS Rapid City, SD

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793
FXUS63 KUNR 192003
AFDUNR

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

.SHORT TERM...(This Evening Through Wednesday Night)
Issued at 203 PM MDT Tue Jul 19 2016

large high pressure ridge will dominate the weather in the
period, bringing hot weather to the region. The fa will remain on
the edge of the ridge with perturbed sw flow continuing on the nw
side of the ridge, perhaps supporting a shra/ts over far nw sd
wed,as one of these impulse advects through the region.

Weak impulse will advect through the area this evening, possibly
supporting widely isold shra/ts over ne WY and far western and
scentral SD. Otherwise, warm overnight lows expected with lows in
the 60s and 70s.

Thermal ridge will time over the fa wed, supporting very warm
temps under clear skies and deep mixing. H85 temps above 35c will
support temps into the 100s most places outside of the black
hills. Have bumped temps up and decided to issue a heat adv one
row of zones west of the excessive heat warning. Weak impulse will
push a sfc trough slowly east wed afternoon, possibly forcing a ts
over far nw sd. CAPE values look marginal as moisture is pretty
shallow. However, fast flow aloft will support deep layer shear
values in excess of 40 knots, supporting a small severe potential
with any cells there. Other cells may develop on the bh/s in peak
heating, but are not expected to push off the bh/s. These cells
would likely produce little rainfall. Any convection will wane
quickly wed eve.

.LONG TERM...(Thursday Through Tuesday)
Issued at 203 PM MDT Tue Jul 19 2016

The upper level ridge begins to flatten a little
bit on Thursday as a weak shortwave races across southern Canada and
an area of low pressure moves into the Pacific Northwest. The Upper
ridge breaks down even further by Friday and over the weekend as the
upper low moves across southern Canada. This will result in near
zonal flow and temperatures cooler off to readings near normal.
Chances for showers and thunderstorms will also increase with the
zonal flow.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 203 PM MDT Tue Jul 19 2016

VFR conditions are expected through the forecast period.
Isolated showers and thunderstorms are possible late this afternoon
and evening over northeastern WY, far western SD, and south central
SD.

&&

.FIRE WEATHER...
Issued At 203 PM MDT Tue Jul 19 2016

Decided to issue a fire weather watch for the
northeastern Wyoming plains for Wednesday afternoon and early
evening. Fire danger will be elevated for the next several days with
hot and dry conditions. Extreme fire conditions will be possible due
to a combination of relative humidity values around 10 percent,
Haines indexes of 6, gusty winds, and dry fuels. Don`t think winds
will reach criteria in Crook County, but since they are combined
with the Weston County plains, they will be included as well.
Northern Campbell County will be borderline due to the winds, but
since it is a watch thought it would be best to include them at this
time.

&&

.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 from noon to 7 PM MDT Wednesday for SDZ002-013-030-
     031-041-042-073.

WY...Fire Weather Watch from Wednesday afternoon through Wednesday
     evening for WYZ259-297-298.

&&

$$

SHORT TERM...JC
LONG TERM...MLS
AVIATION...MLS
FIRE WEATHER...MLS



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