308
FXUS65 KVEF 262002
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
102 PM PDT Fri Jul 26 2024

.SYNOPSIS...Isolated showers and thunderstorms expected for one
last afternoon today across the southern Great Basin and
northwestern Arizona before dry air pushes into the region this
weekend. Temperatures will moderate closer to seasonal averages
before gradually increasing once again through the work week.
Breezy west to southwest winds are expected this weekend which
will increase for danger, especially Saturday. Precipitation
chances return to Mohave County by midweek as monsoon moisture
returns.

&&

.SHORT TERM...Tonight through Sunday.

Moisture will continue to decrease tonight into Saturday as an upper
level shortwave pushes through the region and shifts the flow to a
dry west or southwesterly direction. By Saturday morning, the
probability for over 1.00 inch PWAT is below 20% areawide. This dry
air will stick around through the weekend as PWATs drop to 30%-50%
of normal for this time of the year. No precipitation chances are in
the forecast for any locations through Sunday.

Breezy southwest winds are expected this weekend as the pressure
gradient increases with the passing upper level system. Saturday
will be the windiest day with widespread gusts of 20-30 MPH,
especially through that typical southwesterly wind belt from
Barstow, CA through Las Vegas, NV through Colorado City, AZ. The
probability for impactful winds over 40 MPH is low (20% or less),
however fire danger will increase as there will be significant dry
air entrenched over the region. The highest risk for wildfire spread
will be in Arizona Strip where winds over 20 MPH will combine with
low relative humidity, along with recent fire starts which may
compound issues. In southern Mohave County winds may not be as
strong but they will still be elevated and the risk for fire starts
will be high because of dry conditions and the amount of recreation
that goes on in the area over the weekends. Issued a Red Flag
Warning for much of MOhave County for Saturday due to the overall
heightened risk and at least near-criteria conditions. Elsewhere,
anyone with outdoor plans that would involve activities that
increase fire starts like camping or traveling with chains on cars
should use caution. Winds on Sunday will not be as strong as
Saturday as the upper level system begins to move away from the
area, with gusts across the region topping out at 20-25 MPH.

As the trough moves through the Great Basin region over the weekend,
high pressure will be knocked down and the strongest heights will be
pushed out of the area. This will result in cooler temperatures as
temperatures fall to near normal for the first time in a while by
Sunday. Las Vegas has observed 36 consecutive days of temperatures
over 105 degrees as of yesterday. The previous record was 25 days in
2017. The current forecast calls for a high temperature of 104 on
Sunday, which will end the streak. Latest NBM probabilities show a
71% chance of Las Vegas reaching 105 or higher, with the
deterministic NBM on the cooler side of the box-and-whiskers for the
week. If Las Vegas reaches or exceeds 105 on Sunday, there will not
be another opportunity to break this streak through the remainder of
the forecast period.

.LONG TERM...Monday through Friday.

Period begins with a trough across the Pacific Northwest that
will maintain a southwest flow over the southern Great Basin and
Mojave Desert. This will keep the area dry along with seasonable
temperatures.

On Tuesday and Wednesday, the trough will begin to fill/weaken
allowing ridge which had been suppressed over the southern High
Plains to begin expanding westward. This will allow temperatures to
heat back up above normal along with increasing thunderstorm chances
returning to northwest Arizona Wednesday/Thursday, and potentially a
few hi-based storms west of the Colorado River over the higher
terrain of the Mojave National Preserve and Clark County
mountains.
&&

.AVIATION...For Harry Reid...Southwest winds with occasional gusts
to 25kts can be expected this afternoon and again on Saturday
afternoon.  Winds will diminish slightly overnight tonight, but a
few gusts to 20kts will remain possible.  Any afternoon convection
today will be limited to the Mormon Mesa and Peach Springs
corridors, and no storms are forecast on Saturday. Smoke from fires
over southern California will also move across the area today and
Saturday.  While no significant reduction in surface visibilities is
expected, slantwise visibilities may fall below 7NM at times.
Otherwise, no operationally significant cloud cover is expected
through Saturday.

For the rest of southern Nevada, northwest Arizona and southeast
California...Only isolated areas of convection are forecast this
afternoon and evening, mainly over northwest Arizona. Southwest-
to- west winds will increase across the Mohave Desert this
afternoon, with gusts to 25kts possible in the Vegas Valley and
30kts near KDAG. Winds in the Colorado River Valley will generally
be southerly, around 25kts this afternoon. Near KBIH, light
southerly winds will turn westerly by late afternoon. Smoke from
fires over southern California will also move across the area
today and Saturday. While no significant reduction in surface
visibilities is expected, slantwise visibilities may fall below
7NM at times over southern Nevada and eastern California.
Otherwise, no operationally significant cloud cover is expected
through Saturday. &&

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

&&

$$

SHORT TERM...Nickerson
LONG TERM...Pierce
AVIATION...Planz

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