Heat in Nevada, August 1 to 5, 2018

Area Forecast Discussion
National Weather Service Las Vegas NV
118 PM PDT Tue Jul 31 2018

.SYNOPSIS...Scattered thunderstorms are expected across the area
this evening and Wednesday with the more coverage over the higher
terrain. Drier air will begin to work into the area on Thursday
gradually decreasing the threat of thunderstorms into the weekend.
Temperatures will be within a few degrees above seasonal normal
through the period.
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.SHORT TERM...Tonight through Friday night.

Southerly flow into Inyo County has steadily increased moisture
throughout the day. PW values around 1.25 inches have pushed into
the southern part of the county with the 1 inch value up to around
Independence. Thunderstorms have begun to develop over the Sierra
and across central Nye County along and near the moisture gradient.
Expect an upward trend in coverage to continue, favoring the higher
terrain. Latest mesoanalysis indicated best moisture and instability
over Clark County, but the Spring Mountains have been slow to
initiate convection so far. Still expect development later this
afternoon. The models are indicating some drier air wrapping around
the ridge axis and into eastern San Bernardino and southern Clark
County and Wednesday, which may act to inhibit convection somewhat
there on Wednesday. Models continue to indicate a wave moving
northward into southern California but then stalling out. There is
some potential for the wave to enhance convective activity in
southern San Bernardino County on Thursday afternoon, but confidence
is fairly low at this point. The pattern will begin to shift by
Friday with trough moving into the West Coast and providing a much
drier westerly flow. This will limit convection to Mohave County,
although an isolated thunderstorm cannot be ruled out over the
Spring Mountains on Friday.

.LONG TERM...Saturday through Monday

A shortwave will move through NW Pacific this weekend and should
continue to help break down the strong ridge that has been in place
for the past few weeks. PWATs decrease significantly through the
weekend and with it, precipitation chances. Decreased precipitation
chances after Friday to reflect this continued trend of drying out.
Increasing winds are expected though, especially on Sunday and
Monday as southwest flow increases ahead an incoming system.

Confidence in the forecast decreases significantly for the end of
the forecast. Long range models show a strong trough swinging
onshore the west coast and kicking the monsoonal high out of the
western half of the US completely, however there is little run to
run consistency on how that trough interacts with the high pressure
to the east and how strong the cyclonic flow will be in its wake.
Will watch model trends through the long term as this could bring a
significant pattern change to the area.

Temperatures will remain within a few degrees of normal. Low
confidence in the temperature forecast for the weekend and the
beginning of next week as a pattern change may arrive.

.AVIATION...For McCarran...After a lull in the action this morning,
thunderstorm activity is expected to increase again in and around
the airspace this afternoon. Much like yesterday, there is a good
chance that thunderstorms last into the late evening or early
overnight. Gusty outflow winds are again possible with any
thunderstorms nearby. Tried to highlight the best guess for timing
of the outflow winds in the TEMPO groups, however this may need to
be adjusted. Outflow winds may not arrive until later than current
forecast. Outside of thunderstorm influences, diurnal winds are
expected, and should be light but a bit higher than the past few
days.

For the rest of southern Nevada, northwest Arizona and southeast
California...Similar conditions to yesterday are expected this
afternoon,  with thunderstorms developing across much of the area in
the nary afternoon and continuing through at least the evening.
Better chance that thunderstorms will develop near BIH today, and
could produce some gusty outflow winds. Otherwise

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SHORT TERM...Czyzyk
LONG TERM...Wolf
AVIATION...Boothe

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