Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 200510
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1110 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 06Z TAFS Through 06Z Wednesday Night)
Issued At 1110 PM MDT Tue Jul 19 2016

VFR conditions are expected through the forecast period. Isolated
showers and thunderstorms are possible Wednesday afternoon and
evening over the Black Hills and far northwest 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...Helgeson
FIRE WEATHER...MLS


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