Dust Storm Warning 7, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
820 AM PDT Sat Jul 21 2018

.SYNOPSIS...Moist and unstable air will remain over the region
through the weekend, providing fuel for afternoon and evening
thunderstorms, especially over the mountains. A heat wave will bring
very hot temperatures Tuesday through Thursday, along with lowering
thunderstorm chances.
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.UPDATE...Vort lobe is advancing northward, quicker than what CAM
guidance indicates, and will become more convective along the
leading edge with increased insolation. Increased PoP through 11 AM
this morning. Slight chance PoP now extends northward to the Hoover
Dam and westward into to Henderson and eastward through Mohave
County.

Still concerned with southern Nevada late this morning/early
afternoon with both the diurnal driven and dynamic influences
combining to spread convection across a broad area. Main impacts
will be isolated heavy downpours with embedded thunderstorms and
strong outflow winds. This complex has a history of severe winds
across southwestern Arizona earlier this morning; this morning
observations have estimated 30-40 MPH winds with gusts to 50. Along
with strong outflow, expect blowing dust and lowering visibilities.

.PREV DISCUSSION...215 AM PDT Sat Jul 21 2018

.SHORT TERM...through Monday night. Overall pattern remains
favorable for thunderstorms through the period, although focusing
mechanisms will be tough to pin down. First feature of concern is a
weak vorticity lobe riding around the south side of the big hot
ridge centered over the southern Plains. This lobe was kicking off a
thunderstorm complex in the vicinity of Tucson early this morning,
and is forecast to reach southern Mohave County roughly around
sunrise. Many models suggest the associated storms will be fizzling
by that time, but the remnant lobe could be a focus later in the
day. With this in mind, kept the highest afternoon PoPs over
northern Mohave County, with a secondary max in Esmeralda and
northern Inyo where mountain storms have been prevalent in recent
afternoons and high resolution models paint more precip this
afternoon. For Sunday and Monday, as temperatures rise a little bit
more aloft, expect lesser thunderstorm coverage, with the focus
shifting a bit more to the higher terrain.

.LONG TERM...Tuesday through Saturday.

Little change in overall thinking as strong high pressure shifts
west and impacts the desert southwest through much of the extended
period. The peak of the heat is expected to be Tuesday through
Thursday with temperatures over most areas about 10 degrees above
normal. At this time it looks like temperatures will just remain shy
of records in Las Vegas as the records for Tuesday-Thursday are 117,
115, 116 respectively. With strong high pressure overhead it will be
tough for thunderstorms to develop, but slight chances will remain
over the higher terrain across northern Mohave County along with
central Nevada.
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.AVIATION...For McCarran...Southerly winds around 6-8 kts are
forecast through this morning along with mainly bkn skies around 20k
feet. By late morning, convection will once again develop with
showers or thunderstorms possible in the Las Vegas Valley during the
afternoon. Brief heavy rain along with gusty and erratic outflow
winds will be the main concern with any storm.

For the rest of southern Nevada, northwest Arizona and southeast
California...Isolated to scattered thunderstorms can be expected
again this afternoon around the region. Gusty and erratic winds
along with brief heavy rain will be the biggest impact from storms.
Otherwise typical diurnal winds with speeds generally less than 10
kts.
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.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&

SHORT TERM...Morgan
LONG TERM/AVIATION...Gorelow

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