High Wind in Arizona, March 30, 2017

Area Forecast Discussion
National Weather Service Las Vegas NV
847 AM PDT Thu Mar 30 2017

.SYNOPSIS...A powerful wind storm is expected to impact the region
today, bringing widespread wind gusts of 45 to 65 MPH this
afternoon and evening. Winds will decrease somewhat overnight,
however gusty winds will remain through Friday, especially across
the southern Great Basin. This system will also bring isolated
thunderstorms to areas north and east of Las vegas. A weaker storm
will move across the area Monday.
&&

.UPDATE...All remains on track for a high impact wind day around
the area. No changes made to timing or strength of the system at
this time.

&&

.PREV DISCUSSION... /issued at 337 AM PDT Thu Mar 30 2017/

.SHORT TERM...Today through Friday Night.

It's a deceptively quiet start to the day this morning. The few
clouds that are drifting overhead this morning give little hint of
the powerful wind storm that will impact the region over the next
24 hours. Westerly pre-frontal winds are expected to begin to
materialize over the Sierra and western Mojave desert areas by
mid-morning, spreading east across the rest of the desert by mid-
day. A vigorous cold front will sweep south across the forecast
area between 10am and 8pm PDT (17z-03z), pushing across the Las
Vegas Valley between 3pm-5pm (22z-00z). Westerly pre-frontal winds
are expected to peak shortly before the front, while northwesterly
post-frontal winds will peak with and just behind the front. The
latest high-res guidance has come in slightly stronger than
previous runs, and as a result I've upgraded the Wind Advisory
that was in effect for the Needles/Lake Havasu area to a High Wind
Warning (this means that our entire forecast area is now included
in the warning). Significant blowing dust is likely today,
particularly near dry lake beds across the region. This is
expected to lead to dangerous travel conditions (in addition to
the strong crosswinds). Showers and isolated thunderstorms are
also expected with this system, mainly to the north and east of
Las Vegas with the cold front. Isolated showers will remain
possible across Lincoln, northern Mohave, and northeastern Clark
counties into Friday. Overall, precipitation impacts are expected
to be minimal.

Northwesterly winds in the wake of the front will diminish
overnight across the Mojave Desert. However strong winds will
remain across the southern Great Basin areas. The Wind Advisory on
Friday was expanded to include the Sheep Range and the Las Vegas
Valley, mainly due to the potential for 40+ MPH gusts over the
northwest third of the valley. Winds should begin to taper off
over these areas Friday night.

.LONG TERM...Saturday through Wednesday.

Low pressure if forecast to linger near the Four Corners region on
Saturday before getting nudged eastward by an incoming upstream wave
on Sunday. This upstream system will be the next adverse weather
generator for our area but should pale in comparison to its
predecessor. The time frame for the main event for this next system
will be Monday with another cold front pushing through Monday
afternoon. This system then pushes east by Tuesday, leaving ridging
overhead for Wednesday. Models are hinting at an AR event for the
West Coast heading into the latter part of next week but this is
beyond the official 7-day forecast and I will leave it at that for
now.

Breezy north winds to continue into Saturday with the area still on
the backside of the departing low pressure system. Light winds
return Sunday morning but may begin to respond in the afternoon as
the next system approaches the west coast. Windy conditions are
expected once again on Monday with another cold front pressing south
during the day. The quick hitting nature of the system will allow
winds to decrease faster and all but the Colorado River Valley
should see lighter winds Tuesday and Wednesday. Precipitation
chances will be limited to mainly the mountains of the Southern
Great Basin and perhaps northern Mohave County on Monday with dry
conditions forecast Tuesday and Wednesday. Above normal temperatures
are expected over the weekend then cooling back to seasonal levels
Monday and Tuesday.
&&

.AVIATION...For McCarran...Light winds this morning will rapidly
increase as a powerful storm system impacts the region mid-day today
into Friday. Gusty southwest winds early this afternoon will turn to
the northwest behind a strong cold front this afternoon between 22Z
and 01Z. Northwest gusts of 40-50 KTS are expected this afternoon
and evening. Northwest winds of 20-30 KTS will continue on Friday
with gusts of 35-45 KTS.

For the rest of southern Nevada, northwest Arizona and southeast
California...Light winds generally less than 10 KTS early this
morning. Winds will increase during the morning hours ahead of a
powerful storm system that will impact the area through Friday.
Gusty west to southwest winds will occur along and south of the I-15
corridor with the strongest wind gusts of 40-50 KTS across the
western portions of San Bernardino County. A strong cold front will
push south across the region from mid-day today into this evening.
North to northwest gusts of 40-50 KTS are expected with this cold
front. North winds will linger Friday into Saturday.
&&

.SPOTTER INFORMATION STATEMENT...Strong, potentially damaging
winds are expected today along with areas of significant blowing
dust. Spotters are encouraged to report any significant weather
or impacts according to standard operating procedures.
&&

Short Term...........Wolcott
Long Term/Aviation...Salmen
Update...............Berc/Kryston

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