Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 291034
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
334 AM PDT Sat Jul 29 2017

.SYNOPSIS...Monsoon moisture will continue to push in from the
south increasing chances for showers and storms today through next
week. Storms and showers will be primarily across Mohave, Lincoln
and San Bernardino counties today with chances spreading further
north into other portions of southern Nevada Sunday through mid
week.

&&

.SHORT TERM...today through Monday.

Monsoon moisture is pushing it`s way up the Colorado River and
into eastern San Bernardino and southern Mohave Counties this
morning, with airports in these areas seeing a 15-20 degree
increase in dewpoints over the past 24 hrs. Today, areas with
favorable instability and sufficient moisture will be eastern San
Bernardino Co., Mohave Co. , Lincoln Co. and higher terrain in
Clark County. Storms that develop will be capable of heavy rain,
strong winds and small hail in the aforementioned areas.

A weak disturbance will trail across northern and central Nevada
and will aid convective initiation across the northern zones this
morning and afternoon, with a focused area of activity in Lincoln
County. For Mohave and San Bernardino Counties, should expect
better coverage of showers and thunderstorms through the short-
term period as an easterly wave will track across Arizona and into
southern California. With the dynamic lift provided by the
easterly wave, there is a slight chance of daytime convection
lingering overnight in southern Mohave and southern San Bernardino
Counties on both Saturday and Sunday. Moisture will continue to
work northward and will spread across most of Clark County by
Sunday and Monday increasing chances for storms over the higher
terrain during the afternoon. For the northern zones, models are
agreeing on a ridge of high pressure building into northern Nevada
Monday and suppressing convective activity. Placement of the ridge
will produce an interesting scenario for areas south of
I-15...specifically, Las Vegas and the potential for northeasterly
flow to steer thunderstorms into Las Vegas.

&&

.LONG TERM...Tuesday through Friday.

An easterly wave will be moving off of Baja by Tuesday with high
pressure settling in over northern Nevada. Monsoon moisture pushed
up into the area by the easterly wave will still be in place leading
to a chance of showers and thunderstorms mainly across Mohave, Clark
and San Bernardino Counties. Farther north, the influence of high
pressure looks to keep thunderstorm activity suppressed. It looks
like this pattern will persist through much of the long term,
although there is some indication by the ECMWF that the influence of
the high may weaken by Friday, allowing moisture and thunderstorm
chances to work farther north across most of the forecast area.
Still not a ton of confidence picking one day over another for being
the most active. As we have stated before, it will at least partly
be dependent on cloud cover and any disturbances that form which are
not necessarily depicted very far in advance by the models. So, for
now we are still basically looking for a generic monsoon season
forecast with slight chance pops in the valleys and higher pops in
the higher terrain. Most of the latest model guidance is keeping
temperatures a little above normal during the long term which is
what we are forecasting.

&&

.FIRE WEATHER...Moisture will increase from the south this
weekend, increasing chances for showers and storms into early next
week. Best coverage will be across Lincoln, Mohave, and San
Bernardino counties with more isolated activity across the
remainder of southern Nevada. Storms that develop throughout the
weekend into early next week will have the potential for gusty
winds, heavy downpours, and small hail. Overall winds should
remain relatively light during the heat of the day through the
early next week.

&&

.HYDROLOGY...Creeks, streams and rivers in northern Inyo County
have shown decreasing flows over the last couple of days.
However, some road closures continue in the area. Bishop Creek
Bypass and Big Pine Creek Bypass continue to be utilized to
minimize flows through Bishop and Big Pine. Remember, never drive
through flooded roadways or around barricades. Also, pastureland
or farmland adjacent to creeks, streams or rivers could experience
areas of standing water.

&&

.AVIATION...For McCarran...Winds will stay south to southeast
through the early morning at around 10 knots becoming lighter and
favoring a easterly direction after 15z. Increases in moisture
will lead to possible thunderstorm development across the
surrounding mountains this afternoon. Storms that develop over the
terrain will have potential to send outflows toward the terminal
during the afternoon and evening. Outflow will also be possible
from thunderstorms in NW Arizona, likely producing E-NE winds.
Outside of thunderstorm influences, winds should stay fairly light
and become more southerly after sunset and variable overnight
Saturday. Skies will be FEW to SCT with ceilings down to 12kt
through the period.

For the rest of southern Nevada, northwest Arizona and southeast
California...Scattered showers and thunderstorms are expected
today across Mohave County, eastern San Bernardino, Lincoln, and
higher terrain of Clark County. Outside of any thunderstorm
influences, winds will follow a similar pattern when compared to
last couple of days, mainly light winds in the morning picking up
to about 10-20 knots in the afternoon with a south to southwest
direction. FEW to SCT mid and high clouds expected through the
period.

&&

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

&&

$$

SHORT TERM/AVIATION...Boothe
LONG TERM.............Harrison

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