Area Forecast Discussion
Issued by NWS Las Vegas, NV

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577
FXUS65 KVEF 061016
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
215 AM PST Tue Dec 6 2016

.SYNOPSIS...Northwest upper-level flow and a ridge of high pressure
in the eastern Pacific will keep the area dry and slightly warmer
than average today. A cold front will move through the area tonight
and Wednesday bringing breezy conditions to the Colorado River
Valley and cooler temperatures area wide. Temperatures will warm
back up again during the latter part of the week.
&&

.SHORT TERM...Today through Thursday night.

A dry northwest flow will persist across the region through
Wednesday. A shortwave trough passing through northeast Nevada and
northern Utah will push a cold front through the area tonight and
Wednesday. Temperatures will remain relatively warm today while
areas of gusty west to southwest winds will develop ahead of the
front. Guidance has trended stronger with the winds across western
San Bernardino County with gusts over 40 mph now appearing likely. I
went ahead and issued a wind advisory for the Barstow-Daggett zone
from 10 am this morning until 10 pm this evening. Cooler
temperatures and areas of brisk northerly winds will follow behind
the cold front tonight and Wednesday. At this time it looks like the
strongest winds down the Colorado River Valley will probably be
limited to the Laughlin-Bullhead City area, in other words not
widespread enough to justify a wind advisory. We will continue to
monitor model trends for possible issuance with later runs. Very
flat ridging will develop over California and Nevada Wednesday night
through Thursday night leading to the beginning of a warming trend
and mainly dry conditions. Models indicate overrunning moisture
sufficient enough to mention a chance of light snow in the Sierra
but the rest of the area is expected to remain dry with some cloud
cover as the Sierra will intercept the best/deeper moisture.

.LONG TERM...Friday through Monday.

Model differences continue to muddle details in the long term
period. In general, quasi-zonal flow will be in place across the
region. However, at least one wave will slide across the Great Basin
during this time frame. The latest runs of the operational and
ensemble GFS are more amplified with this feature than previously
forecast while the ECMWF is 12-24hrs slower and much less defined.
The biggest impact from these differences will be the winds over the
weekend. The GFS solution would result in much stronger winds both
ahead of and behind the wave. For the moment have basically split
the difference in the official forecast. Precipitation-wise, low
chances for mountain snow showers will exist Friday through Sunday
across the Sierra, and to a lesser extent across the southern Great
Basin. Overall the threat from precipitation is fairly low at this
time. However, a southerly shift in the storm track could result in
higher snow amounts in the Sierra than currently forecast and will
need to be monitored. Windy conditions will persist across the
Sierra crest through the period.

Temperatures are generally expect to be 2-5 degrees above normal
Friday through Monday.
&&

.AVIATION...For McCarran...Light, diurnally-driven winds and VFR
conditions are expected through much of today. There could be a
brief period of southwest winds this evening but winds will
transition to a northerly direction fairly quickly tonight with
gusts possibly up to 20 knots at times later tonight and early
Wednesday.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Light, diurnally-driven winds and VFR conditions are
expected across the area through this morning. Areas of gusty west
to southwest winds will develop late this morning or early this
afternoon with the strongest winds in western San Bernardino County
and near the Sierra Crest where gusts over 40 knots are possible.
Northerly winds will spread from south to east tonight and Wednesday
with areas of gusts in the 20 to 30 knot range. VFR conditions are
still expected this afternoon through tonight and Wednesday.
&&

.SPOTTER INFORMATION STATEMENT...Spotter activation will not be
needed.
&&

$$

Short Term/Aviation...Harrison
Long Term...Wolcott

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