Tornado in Arizona, July 24, 2020

Area Forecast Discussion
National Weather Service Las Vegas NV
906 AM PDT Fri Jul 24 2020

.SYNOPSIS...
Storm chances continue today over Mohave County and the higher
elevations of the Sierra Nevada with dry conditions expected
elsewhere. Temps will continue to run near to below normal through
the weekend with a light breeze each day. Another potential shot
at increasing monsoon moisture will come mid to late next week.

&&

.UPDATE...Convective initiation has begun a tad earlier than
expected today along a tight north-south moisture/instability
gradient which is paralleling the the Colorado River Valley.
Thunderstorms that develop may impact Lake Mead as steering flow
will push developing convection along the boundary northeastward.
Expect lightning and gusty outflow with these thunderstorms
throughout the day. Training convection may also pose isolated risks
of flash flooding as well across all of northwest Arizona. Updated
the PoP forecast to reflect the earlier convection.

Overall, the instability is much higher across Mohave County today
compared to yesterday. That said, more substantial updrafts should
result in more intense downburst amid DCAPE values 1000-1500 j/kg.
The main difference between convection today from yesterday is lack
of nocturnal convection chances. Outside of northwest Arizona,
thunderstorm chances are below mentionable.

&&

.SHORT TERM...Today through Sunday.

Late night convection over eastern Mohave County subsided early this
morning with the last few lightning strikes exiting around 3 AM.
The now weakened shortwave will exit northeastward today taking
any supporting mid/upper level dynamics with it. Low/mid level
moisture will be shifted slightly eastward from where it was
yesterday as mid-level southwesterly flow noses in some drier
air from the west. This will leave best chances for showers and
storms today over Mohave County, east of the Colorado River Valley
as well as the higher elevations of the Sierra. Winds will come
down another five mph from yesterday with a light breeze
continuing through the weekend. As a result, wildfire danger will
become a lower concern. We will remain under dry, southwesterly
flow through the weekend as a nearly stationary mid- level trough
sits just off the north central Cali coast and ridging slowly
builds westward towards the Four Corners region. Chances for
storms will continue to trend downward on Saturday being confined
to along the Mohave County border with Yavapai and Coconino
counties and areawide dry conditions expected for Sunday. Near to
below normal temps will continue for the weekend.

.LONG TERM...Monday through next Thursday.

By early next week there is a signal from ensembles that the typical
monsoon ridge will become situated near the Four Corners,
potentially priming the pump for a moisture surge. Additionally,
Tropical Storm Hanna may be a key factor in a surge of moderate to
high-grade moisture by Wednesday or Thursday next week. Taking this
with a grain of salt at the moment, but the potential for a decent
period of thunderstorms and attending threats is increasing.

Also, with the subtropical ridge developing, temps will increase
above average once again next week.

&&

.AVIATION...For McCarran...
Light and variable winds are expected to start the period before
shifting to the southeast mid to late this morning. Similar to
yesterday, southeast winds will continue at 8-10 knots through
mid-afternoon when winds should become more southerly at similar
speeds. A few gusts to around 15-18 knots will be possible.
Storms will be possible again this afternoon to our east over the
Mormon Mesa and Peach Springs. Drainage winds will settle in this
evening at speeds of 8 knots or less. A few clouds aoa 12k feet
are possible this afternoon.

For the rest of southern Nevada, northwest Arizona and southeast
California...Winds will generally be south to southwest today at
speeds of 10 to 15 knots with gusts around 20 knots possible this
afternoon. Storms will again be possible over Mohave County and
the southern Sierra this afternoon with gusty outflows potentially
making it to KBIH, KEED and KIFP. Decreasing storm activity and
lighter winds expected after sunset. A few clouds aoa 10k feet
expected.

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.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&

UPDATE/LONG TERM...Boothe
SHORT TERM...Guillet
AVIATION...Guillet

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