Weather Service Report

FXUS65 KVEF 290511

Area Forecast Discussion
National Weather Service Las Vegas NV
1011 PM PDT TUE JUN 28 2016

.SYNOPSIS...A moderate increase in moisture that has accompanied a
disturbance moving toward central Nevada will linger over the region
the rest of the week leading to isolated to scattered afternoon
thunderstorms...especially over and near the mountains.

.UPDATE...Activity has diminished quite a bit over the past couple
of hours. There is still some lingering convection in eastern San
Bernardino and southern Clark Counties where sufficient CAPE still
exists, but that should be diminishing by midnight. Several strong
winds gusts were noted in and around the Las Vegas Valley with the
multiple rounds of thunderstorms late this afternoon and early this
evening in the 50 to 55 mph range. The inverted trough that has been
the primary feature is currently located over central Nevada and
continues to move off to the north...northeast. A weak shortwave and
deformation zone is forecast to move across the southern Sierra and
into central Nevada overnight and into tomorrow. This will likely
aid in initiating... focusing convective active tomorrow, but may
also provide some mainly isolated convection across the north from
the Sierra eastward into Esmeralda and central Nye Counties
overnight. I've added PoPs there and increased cloud cover across
those areas for the overnight hours. 

305 PM PDT TUE JUN 28 2016

.SHORT TERM...tonight through Thursday night. 

Recent satellite loops showed a well defined circulation moving over
central Nye county this afternoon which was associated with the
inverted trough that has been responsible for bringing a modest
increase in moisture...providing fuel for some thunderstorms.
Surface dewpoints were generally in the upper to 30s to lower 40s
across much of the region. The most active area so far has been
central Mohave county up to the eastern fringes of Lake Mead where
the highest pocket of moisture and instability has resided in the
wake of the inverted trough. This area will continue to be a focus
for convection this afternoon...but we will also need to watch the
southern Sierra and Owens Valley as well. Isolated thunderstorms
will also be possible over Clark and eastern San Bernardino counties
before surface heating is lost this evening. Thunderstorms will have
the ability to produce strong outflow this afternoon and evening
which may initiate other convective cells.

Convection will diminish overnight then Wednesday and Thursday look
to be days with diurnal isolated to scattered thunderstorms driven
primarily by surface heating. There is a slight drying trend over
southeast California and southern Nevada Thursday but models
continue to indicate a broad push of low level moisture up from
northern Mexico and Arizona Thursday night into early Friday morning.

.LONG TERM...Friday through Monday.

Models consistent and in good agreement indicating a resurgence of
low level moisture back west across the Colorado River into eastern
San Bernardino, Clark and Lincoln Counties Friday and Saturday.
On Friday, GFS surface computed CAPE and 0-1km most unstable CAPE
shows values in excess of 1000 J/kg southeast of a line from
Twentynine Palms-Bullhead City-Peach Springs. On Saturday, GFS shows
values in excess of 1000 J/kg over central/southern Clark County and
the Mojave Natl Preserve in northeast San Bernardino County.
Increased POPs in the lower Colorado River Valley and southern
Mohave County based on the amount of instability forecast

Beyond Saturday models differ in the overall pattern by the Fourth
of July. Models flip-flopped solutions this morning with the ECMWF
now showing more pronounced southwest flow associated with deeper
trough over the Pacific Northwest/northern Great Basin. Meanwhile,
the GFS now keeps a 594 DM H5 height contour centered over Arizona.
Like last night outcome looks similar with both models spreading a
drier more stable air mass over the region. The ECMWF would be the
driest solution with guidance suggesting surface dewpoints falling
back into the teen and 20s for Las Vegas on the 4th while the GFS
shows 20s and 30s. If the ECMWF pans out expect stronger southwest
wind gusts for revelers to contend with on the Forth of July. 

Influx of moisture/cloud cover should have some affect on
temperatures Friday/Saturday. Once drier air spreads in temperatures
should warm to above average Sunday and Monday. 


.AVIATION...For McCarran...Southwest winds will persist overnight,
but generally expected to be below 10 kts. Isolated thunderstorms
tomorrow in the valley with more scattered coverage in the higher

For the rest of southern Nevada...northwest Arizona...and southeast
California...Isolated showers and thunderstorms will be possible
overnight. Winds are expected to be mainly light and favoring
diurnal trends, however, outflow boundaries may bring periods of
gusty winds with gusts of 35 knots or more possible, especially near
thunderstorm activity.

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



Short Term...Adair 
Long Term...Pierce 

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