Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 210523
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
923 PM PST Thu Feb 20 2020

.SYNOPSIS...Dry conditions will remain in place through tomorrow
with temperatures a few degrees above normal along with a few high
clouds at times. A Pacific Storm System is still forecast to
swing into southern California Friday night then move across the
Desert Southwest on Saturday. Confidence continues to increase for
widespread precipitation Saturday. Some locations may see some
moderate to heavy rainfall at times, isolated thunderstorms south
of Interstate 40, and high elevation snows in the Spring
Mountains and Sheep Range.

&&

.UPDATE...Quiet weather conditions are expected across the region
through the night with some thin high clouds over mainly the
southeastern third of the area, seasonal temperatures and light
winds. The forecast is in good shape and no updates are needed at
this time.

&&

.PREV DISCUSSION... /issued at 215 PM PST Thu Feb 20 2020/

.SHORT TERM...through Friday night.

A deepening low roughly near 40N/130W will continue to digging over
the eastern Pacific overnight bringing an increasing southerly flow
to the area. This increasing southerly flow on Friday will help
produce additional mixing and help raise temperatures to about 8-10
degrees above normal.

.LONG TERM...this weekend through early next week.

The well anticipated closed low originating from the Pacific will
begin its trek eastward Friday afternoon with the center reaching
the California coast by Saturday morning. This will firmly place
much of the desert southwest in an area of strong dynamical lift,
bringing widespread precip to the area beginning early Saturday
morning but persisting possibly throughout the day. Deep moisture
will work into the area from the south with rain beginning over the
western portions of the forecast area late Friday night with much of
the forecast area seeing widespread rainfall by Saturday morning.
Rainfall amounts have not changed much, but models are generally
calling for totals between a quarter and three quarters of an inch
by Saturday night across areas generally east of Inyo and central
San Bernardino Counties. Best forcing and insability will remain
over southern San Bernardino into southern Mohave County where the
possibility of thunderstorms exist Saturday afternoon.

This system is not particuarly cold with snow levels remaining
around 6000 feet and above. The main concern for impactful snowfall
will occur in the Spring Mountains and Sheep range where 6-12 inches
will be possible by Saturday evening. Went ahead and hoisted a
Winter Weather Advisory for elevations above 6500 feet from 8am to 8
pm Saturday.

Rainfall will gradually end from west to east late Saturday
afternoon as the low center gradually shifts into western Arizona
Saturday evening. Rainfall is expected to continue for much of the
overnight period over Mohave County along with portions of Lincoln
County. Snow is not expected to be a major impact, but 1-3 inches of
snow will be possible on the higher passes in Lincoln County which
include Panaca Summit.

The models are still indicating some residual precipitation lasting
into early Sunday morning over eastern Mohave County, but most of
the precip is expected to be east of the forecast area by late
morning and afternoon.

Ridging will build into the region late Sunday and continue through
much of the week keeping the area dry and returning temperatures
back to a few degrees above normal. Occasional gusty north winds at
times will also occur, mainly down the Colorado River Valley.
&&

.AVIATION...For McCarran...Expect iurnal trends in the way of
southwesterly winds through the overnight period generally below 7
kts. A light northeasterly wind will take hold after sunrise with
no operationally significant cloud cover through the TAF period.

For the rest of southern Nevada, northwest Arizona and southeast
California...Northerly winds will continue along the Colorado
River Valley overnight. A few hours after sunrise, northerly
gusts 20-25 kts will pick back up and last until sunset Friday
night. Elsewhere, light and diurnal trends expected with no
operationally significant cloud cover through the TAF period.

&&

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

$$

UPDATE...Salmen

DISCUSSION...Gorelow
AVIATION...Varian

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