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Area forecast discussion 
National Weather Service Las Vegas Nevada
857 am PDT Monday Aug 3 2015

Synopsis...dry and stable conditions are expected over much of the
region today. Some weak instability and residual moisture remains
over the Sierra for a slight chance of afternoon thunderstorms...but
by Tuesday and Wednesday the entire forecast area is expected to
remain dry. Thunderstorms chances will creep back into Mohave County
by the end of the week.

Update...the latest hrrr and local hi-res models forecast light quantitative precipitation forecast
over northern Lincoln County this afternoon so went ahead and
included a slight chance of thunderstorms primarily north of Pioche
for this afternoon. Current temperatures are running 6-10 degrees warmer in
the Las Vegas Valley than at this time yesterday however, it is
likely due to the warmer start this morning. The current forecast,
including temps, looks in good shape. -Salmen-

Aviation...for McCarran...benign weather continues today with
diurnally driven winds expected through tonight. No operationally
significant weather is expected through at least mid-week.

For the rest of southern Nevada...northwest Arizona...and southeast
California...thunderstorm chances this afternoon will be limited to
far northern Inyo...Esmeralda and northern Lincoln counties. Dry
conditions are expected areawide Tuesday and Wednesday. Expect quiet
weather at all taf sites with diurnally driven winds through
tonight. -Salmen-

Previous discussion...230 am PDT...

Short term...through Wednesday night.

Outside of a few clouds over Esmeralda and far northern Lincoln
counties skies are clear across the area. Models are indicating
fairly stable conditions across the region today expect for a small
area of negative lifted indice's over the southern Sierra this afternoon. There
is limited moisture to work with...but can not rule out a
thunderstorm or two so left in slight chance probability of precipitation for that area. The
rest of the area will remain dry with just a few flat cumulus
developing during the day. Trough off the West Coast will increase
the southwest flow over the area Tuesday and Wednesday drying US out
even more at the lower levels...although we may see some high clouds
at times. Winds are not expected to be much of a concern...but we
will likely see gusty winds at times during the afternoons. With the
increased southwest flow we will start to see high temperatures
climbing back to above normal readings by this afternoon.
Temperatures should warm even more Tuesday and especially Wednesday
as we will likely see better mixing and higher heights. Temperatures
on Wednesday could reach readings that we have not seen in almost a
month...but are still expected to remain well below any heat warning

Long term...Thursday through Monday.

Operational model guidance continues to remain in good agreement in
developing an upper level low off of the central California coast
Thursday and bringing it inland through the weekend. This coupled
with high pressure off to the east will act to funnel a plume of
moisture back into our eastern zones...particularly Mohave County
Thursday and Friday. Of particular interest this evening is the new
found consistency among the last several operational model runs with
respect to the positioning of the high to the east. The 12z and 00z
runs of the GFS and European model (ecmwf) place the high further east over
southcentral/southeast New Mexico...leaving flow aloft mainly
influence by the low to the west. These runs are supported by their
associated ensemble members this evening...thus raising confidence.
If this trend does is expected that this surge of
moisture will be relatively short-lived...with the bulk of the
action expected on Friday before dry air quickly sweeps across the
area from west to east Friday night through Saturday. Forecast
moisture profiles from the GFS continue to indicate precipitable water values of 1-
1.25 inches in Mohave County...with a sharp west to east gradient
across Clark and southern Lincoln counties ahead of the surface
front. Though this currently looks to be a quick event...the amount
of forcing with the surface front...available instability...and
shear aloft (e.G. 35-40 kts at 500mb) could yield a wider coverage
of thunderstorms over the eastern zones Friday. Probability of precipitation will be fine
tuned as the finer details regarding the important features (mainly
the positioning of the high) are resolved in the coming days. The
other story with this particular system will be the breezy to gusty
southwest to west winds on the system sweeps across the
Great Basin.

Saturday...a drying trend will quickly resume as the upper low
begins to exit the region. This will usher in cooler
temperatures...with afternoon highs running 4-5 degrees below
average through the end of the period. Otherwise...benign weather
will be back as a dry southwest flow regime resumes across the area.



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