Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 271007 CCA

Area Forecast Discussion
National Weather Service Las Vegas NV
200 AM PDT SAT AUG 27 2016

.SYNOPSIS...Scattered showers and thunderstorms will remain possible
today keeping regional temperatures on the cool side for late
August. Temperatures will return closer to normal Sunday into early
next week. A weather system will arrive midweek and bring a renewed
chance for showers and storms over our eastern areas and cool
temperatures back down a few degrees for the latter half of the


.SHORT TERM...Through Sunday night.

Fairly active night has taken shape as a weak upper level low
developed southward into our region and combined with favorable jet
dynamics to produce clusters of strong thunderstorm activity. Much
of the activity as of early this morning has trended weaker but
remains persistent across central Mohave county and the Mojave
Preserve area. A secondary batch of showers and thunderstorms is
moving southward out of Lincoln county and looks to drive south
across Clark and Northern Mohave counties early this morning.
Considerable convective cloud cover will hinder the heating somewhat
across Mohave county later this morning but further west things will
likely get active again under the influence of cool temperatures
aloft and lingering moisture. Maintained chance PoPs across much of
Southern Nevada and eastern California today and early indications
are the Mojave Preserve area and parts of the Spring mountains may
see a few strong storms this afternoon. Once the cloud cover
clears...convection will again fire across Mohave county as well.

The low will begin to push east Saturday evening which will result
in a decreasing influence on our weather and increasing stability.
Some residual moisture may result in a few isolated storms across
the higher terrain of southern Nevada and Northwest Arizona but
overall things will be much more dry. Temperatures today will be
sharply cooler than past days thanks to the close proximity to the
upper low and abundance of cloud cover, with temperatures returning
to near normal sunday.

.LONG TERM...Monday through Friday (From Previous Discussion).

Upper level low approaching central California Monday will help
suppress a strong ridge and bring an increasing southwest flow into
the region Monday and early Tuesday. This increasing southwest flow
will bring better mixing to the region along with increasing heights
leading to about a 4-6 degrees jump in temperatures Monday
afternoon. Moisture is expected to remain well east of the forecast
area and no precipitation is expected. By Tuesday, an inverted
trough over the western Gulf of Mexico will slowly track west and
bring an increase in moisture to portions of Arizona with PW values
approaching an inch and a half over the southern half of the state.
Still looks to dry for northwest Arizona and the models are not
indicating much in the way of instability to include any pops in the
forecast. Moisture and instability will increase Wednesday over
northwest Arizona as the inverted through continues to track west.
The GFS indicates the 1" PW line basically extending from eastern
San Bernardino Co through far eastern Clark and through northern
Mohave Co with the 1.25" line over far eastern Mohave. Instability
is also expected to increase leading to a better chance of
thunderstorms during the afternoon. As of now it looks like the best
chance will remain over the eastern half of Mohave County and did
raise pops slightly for that area.

Differences in the GFS/ECMWF on Thursday as the GFS shows the trough
off the west coast to deepen which increases the southwest flow over
the area and pushes much of the moisture east. However, the ECMWF
increases high pressure over the southern states which allows
moisture to be pulled north into Arizona keeping the chance of
showers and thunderstorms going though Thursday and Friday. There is
also some indication from the ECMWF that moisture could be pushed
further west affecting Clark and eastern San Bernardino Counties. At
this time will keep the slight chance over northern Mohave through

Temperatures will remain above normal through Tuesday, but will cool
about 3-5 degrees Wednesday and Thursday as the trough digs off the
coast and brings lowering heights to the area. &&


.AVIATION...For McCarran...Scattered thunderstorms will remain a
possibility this morning and again this afternoon. Winds will be
variable based on outflow boundary activity but should tend to favor
south or southeast winds. Sct-bkn clouds expected through mid
morning above 10k with scattered clouds and a chance for storms in
the afternoon. Drier conditions expected Sunday.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Scattered thunderstorms expected mainly across Southern
Nevada and Northwest Arizona as well as far eastern California
today.  Convective turbulence and gusty surface winds can be
expected in these areas. Widespread cloud cover can be expected east
of the Colorado River this morning with increasing clouds during the
afternoon as thunderstorms redevelop. Otherwise...generally light
southerly winds favored for most TAF sites.


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


Short Term/Aviation...Outler
Long Term...Gorelow

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