Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 220954
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
354 AM MDT FRI JUL 22 2016

.SHORT TERM...Today Through Saturday Night
Issued at 355 AM MDT Fri Jul 22 2016

Broad upper ridge over central US with westerly flow over the
northern plains will give way to a trof moving eastward from the
Pacific Coast today. Shortwave over Great Basin will ride over the
crest of the ridge along the Dakotas border late today. Surface
trof will remain over MT-WY/SD border today. Cold front will
follow Saturday, pushing across the Dakotas and bringing cooler
and drier air to the forecast area.

Convection will develop early in the afternoon over northeastern
WY and Black Hills along the surface trof as higher dewpoints are
advected across western SD. CAPE and shear not very impressive
over northeastern WY, and with southwest winds behind the trof,
storms will be high based and will be capable of producing dry
lightning. Best chance of severe storms will be over northwestern
SD where along frontal boundary. Although huge CAPE values exist
over south central SD, do not expect convection until trof/cold
front moves through late Fri night/early Sat morning. temperatures
will be warmer today and with high dewpoints, will issue a heat
advisory for rest of SD plains where HI will reach 95-100.

Showers will clear quickly Saturday morning as cold front pushes
across the Dakotas, bringing cooler and drier air to the forecast
area. Expect gusty northwest winds as 700mb temps cool 8-10 deg
with deep well-mixed layer and much lower dewpoints.

.LONG TERM...(Sunday Through Thursday)
Issued at 355 AM MDT Fri Jul 22 2016

 Upper flow will be quasi-zonal Sunday through next Thursday,
with periodic shortwave troughs bringing daily chances for showers
and thunderstorms. Temperatures Sunday will be near seasonal
averages, warming into the 90s early next week as return flow
develops behind high pressure, with a slight cooldown possible
towards the end of the week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 355 AM MDT Fri Jul 22 2016

Isolated thunderstorms are possible this morning from
northeast WY into northwest SD. Potentially severe storms will
develop this afternoon with local LIFR conditions possible with any
storms. Outside of storms, VFR conditions are expected. Early
Saturday morning, a strong cold front will bring gusty northwest
winds to the area.

&&

.FIRE WEATHER...
Issued At 355 AM MDT Fri Jul 22 2016

As surface trof crosses the area midday, southwest winds
increase, with gusts around 25 mph and relative humidities falling
to around 15 percent. Isolated thunderstorms will develop during
the afternoon and early evening, with dry lightning possible
with the high cloud bases and little precipitation expected. Haines
indices will reach 6 by midday. A cold front will cross the area
after midnight Friday night with gusty northwest winds behind it.

&&

.UNR Watches/Warnings/Advisories...
SD...Excessive Heat Warning until 6 PM MDT /7 PM CDT/ this evening
     for SDZ014-032-043-044-046-047-049.
WY...Fire Weather Watch from noon MDT today through this evening
     for WYZ259-297-298.

&&

$$

SHORT TERM...55
LONG TERM...Pojorlie
AVIATION...Pojorlie


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