Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 070404
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
902 PM PDT Thu May 6 2021

.SYNOPSIS...Low pressure passing by to the north will bring gusty
winds Friday, resulting in enhanced fire danger. Temperatures will
come down several degrees over the weekend into early next week
before ramping back up again late next week.
&&

.UPDATE...Wind gusts dropped below 20 mph across most of the region
this evening under a clear sky. South-southwest winds will increase
late Friday morning through the afternoon, but the latest high res
and ensemble-based models support the gusts generally 25-35 mph. No
changes needed to the going forecast detailed in the previous
discussion.
&&

.PREV DISCUSSION...
134 PM PDT Thu May 6 2021

.DISCUSSION...through next Thursday. Low pressure in the
southeastern Gulf of Alaska today will roll east along the Canadian
border Friday, dragging a trough and associated cold front across
our area. Winds will be the main concern. Ahead of the front, expect
southwesterly winds to increase in Mohave, Lincoln, Clark, southern
Nye, and western San Bernardino counties in the afternoon. These
winds, plus low humidity and dry/drying brush, will lead to
increased fire danger, especially over eastern Lincoln and northern
Mohave counties. After discussions with fire partners and
neighboring Weather Service offices, have decided to forgo any Red
Flag Warnings, as NBM 1-D viewer shows less than 10 percent
probabilities of 35 mph gusts. Another area of concern will be
western San Bernardino county. Wildfire concerns are not as great
there due to sparse fuels, but there could be a short period of
strong westerly winds in the late afternoon or early evening as the
cold front passes and the flow is enhanced through the Tehachapi
Gap. NBM 1-D viewer shows less than 10 percent probability of 40 mph
gusts at Barstow-Daggett and Fort Irwin, so will forgo a Wind
Advisory at this time, but this area has been known to overachieve,
so will need to keep an eye on it. Post-frontal winds are
unimpressive Friday night and Saturday, which makes sense given that
the parent low is moving east rather than south. However...by
Saturday night, the low is forecast to stall over or near Montana as
it runs into blocking high pressure over Saskatchewan. The models
then diverge with how far the low might retrograde back to the
southwest, with the GFS showing more retrograding (and thus precip
chances returning to the far eastern CWA) and the non-GFS consensus
keeping the low farther east and our area under dry northwest flow.
Cannot rule out the GFS solution, but see it as a low probability
outlier, so will keep a dry forecast with less wind than the GFS
suggests. Thereafter, there is good agreement on high pressure
building back in, leading to another warming trend by the end of
this forecast period.
&&

.FIRE WEATHER...Near-critical conditions are expected Friday,
especially in eastern Lincoln and northern Mohave counties. The
latest guidance shows less than a 10 percent chance for gusts over
35 mph in these areas, so will not issue a Red Flag Warning.
Slightly lighter winds are expected over the weekend, lessening the
danger.
&&

.AVIATION...For McCarran...East to southeast winds from 8-12 kts
with gusts to 15-20 kts are expected to shift to a southerly
direction between 21-23z and increase to 12-22 kts. These winds will
continue into the evening hours before diminishing overnight. Only a
few high clouds at times.

For the rest of southern Nevada, northwest Arizona and southeast
California...South to southwest winds 10-25 kts...especially across
the northern Owens Valley where wind gusts up to 30 kts are
possible. These winds will persist into early evening before
diminishing overnight. Just a few high clouds expected.
&&

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

$$

UPDATE...Adair
DISCUSSION...Morgan
AVIATION...Salmen

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