Strong Wind in California, February 24 to 25, 2021

Area Forecast Discussion
National Weather Service Las Vegas NV
1148 AM PST Wed Feb 24 2021

.SYNOPSIS...A cold front will pass through the region today,
bringing gusty northerly winds through Thursday as well as a stark
drop in temperatures seen between Wednesday afternoon and Thursday
afternoon. Temperatures will rebound to near seasonal averages by
the end of the week, but will drop once again over the weekend as
another weather system drops down from the Pacific Northwest.
&&

.SHORT TERM...Today and Thursday.
Not much change from the previous forecast's overall
thinking...still believe the cold front will be pushing through
beginning this afternoon and through the overnight period, slow a
bit as it traverses through southern Nevada, then push through the
Colorado River Valley.

Did decide to go ahead and include the Owens Valley (Zone 520) to
the wind advisory. The northern orientation of the winds looks like
it will result in down valley channeling of the winds throughout the
evening and overnight. The down valley orientation should be less of
a concern for crosswinds and blow overs, but wind gusts over 40 mph
look likely south of Olancha which may result in some minor blowing
dust and other minor strong wind impacts. Timing will follow the
rest of the Inyo county advisory.

Another area of concern for overnight is a potential downslope event
on the south side of the Spring Mountains, potentially impacting
Pahrump. Just about all hi-resolution outcomes highlight this area
(and secondarily Red Rock area), for downslope winds potentially
eclipsing 60 mph gusts and 40 mph sustained winds after 10 pm
tonight. This would be a highly localized area, but could impact SR
160 and east as well as Wheeler Pass Rd. Any communities east of the
SR 160 corridor from HWY 95 through Pahrump could see very strong
north/northeast winds. Considered an upgrade to a High Wind Warning
for this zone alone but impacts would be fairly minimal if the winds
don't reach the corridor which is far less certain. A short fuse
upgrade may be needed but for now briefed partners with targeted DSS
in this area for the potential.

Lastly, winds are expected to stay elevated through at least 21Z
Thursday for the Colorado River Valley still with gust potential
over 50 mph. Lake waves continue to be the main concern with typical
advisory wind impacts possible for locations such as Needles,
Laughlin, Bullhead City, and Fort Mohave. Patchy blowing dust will
again be a low end chance as well.

.LONG TERM...Saturday through early next week.
The next system of interest over the weekend continues to show some
uncertainty among ensemble members but now certainly quite a bit
drier than at this point yesterday. Initially, this system was about
55/45 for cutting off a low from the mean synoptic flow to the north
and resulting in a deeper/slower low over the desert southwest, but
as of the 00Z suite and now the 12Z runs coming in, that is looking
less likely. There is still indications that the low will indeed
close off over Arizona (12Z GFS) but never fully dephasing from the
mean synoptic flow and keeping a more progressive motion eastward.
This results in two things: a drier outlook and a windier outlook
but for a shorter period. Not too much unlike the system we will be
experiencing tonight.

In fact, both the 00Z and 12Z deterministic solutions show very
similar details in the vertical wind profile for tonight vs Saturday
night, with low level winds slightly favoring tonight. Thus,
adjusted winds to reflect this in the grids. This would mean that
another round of wind advisories will likely be needed over the
weekend, should this continue to be the case through the rest of the
week.

Moving ahead into next week, much less certainty exists, especially
if only relying on the deterministic runs of the mid-long range
models. Diving into the ensemble cluster analysis, there are several
potential outcomes, ranging from a strong, slow moving low over the
Pacific tapping into a brief but substantial AR (GFS) to a much
weaker shortwave pushing quickly east and even ridge building over
the western CONUS by Wednesday of next week. Interestingly, the 13Z
NBM has not introduced significant PoPs or QPF into the forecast,
and don't have the confidence to include it manually so as it stands
now, a dry forecast will continue, but this may change as more
clarity is introduced.

&&

.AVIATION...For McCarran...Winds will be light variable through much
of the afternoon before a cold front moves through southern NV and
brings gusty northwest winds into the Las Vegas Valley by early
evening Wednesday. Gusty northwest winds are possible between 02-03Z
Thursday (this evening), with sustained winds of 15-25 knots and
gusts to around 30-35 knots. These strong winds are expected to be
fairly brief, only lasting to around 06-07Z tonight, but winds will
remain elevated with gusts to 20-25 knots overnight Thursday. No
operationally significant clouds expected.

For the rest of southern Nevada, northwest Arizona and southeast
California...A cold front is expected to move through southern NV,
southeast CA, and the Lower Colorado River Valley later this
afternoon/early evening, bringing strong northwest winds across the
region. Expect sustained winds of 15-25 knots and gusts to around 30-
35 knots across much of the region - strongest winds will be down
the Colorado River where gusts to around 40-43 knots will be
possible. The strongest winds are expected to be fairly brief, only
lasting 3-5 hours, but northerly winds will remain elevated with
gusts to around 20-25 knots overnight Thursday across much of the
region. No operationally significant clouds expected.

&&

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

DISCUSSIONS...TB3
AVIATION...Kryston

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