Forecast Discussion


FXUS65 KVEF 241939
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1239 PM PDT Mon Jun 24 2024

.SYNOPSIS....Scattered showers and thunderstorms will be possible
through this evening across eastern areas of the region. Higher
moisture levels will spread northward overnight and on Tuesday,
bringing slightly higher precipitation chances into Clark,
Lincoln, and San Bernardino counties. By mid-week, an approaching
trough of low pressure will push the moisture eastward, decreasing
precipitation chances. Above normal temperatures are expected to
continue through at least the beginning of next week.
&&

.SHORT TERM...Through Wednesday.

Southerly flow will continue across the region through Wednesday,
maintaining the potential for shower and thunderstorm activity
each day. The 12Z sounding for LAS shows 1.08" of precipitable
water (PWAT) over the area, which is a slight increase over the
0.97" measured 24 hours ago and .55" higher than the .53" that is
normal for this day. Moisture levels further south in the Colorado
River valley are higher, with PWAT values of 1.5" to 1.6"
forecast near Lake Havasu. While there is sufficient moisture for
convection, instability will be limited with CAPE values of
1000-1500 J/Kg forecast along the lower Colorado River and lower
values elsewhere. Given this, showers and thunderstorms are
expected this afternoon and evening, mainly across Mohave,
southern Clark, and southern and eastern San Bernardino counties.
A few storms will also be possible over the Sierra and White
Mountains in Inyo and Esmeralda counties. Shower and thunderstorm
chances will spread farther north tomorrow as higher PWATs
continue to surge into the region. Instability will remain
limited, with the highest CAPE values remaining over Mohave
County, keeping the best threat of storms in that area. As a
trough of low pressure begins to move into the Great Basin on
Wednesday, the higher moisture values will shift east, limiting
convection to eastern Mohave and northeast Lincoln counties.

Although moisture values are anomalously high, the lower levels
are dry resulting in elevated DCAPE values near 1900 J/Kg, as
observed on this morning's sounding. Any storms that do develop
will have the potential to produce gusty outflow winds in excess
of 40mph. Locally heavy rainfall is also possible, although the
probability of any given area receiving over 1.0" in an hour is
less than 10%. WPC's excessive rainfall outlook maintains a
marginal threat mainly in Mohave and eastern San Bernardino
counties this afternoon but shifts that threat to the north to
include eastern Lincoln County tomorrow. While the threat exists,
the chance of any given area seeing more than 1" of rain in an
hour will remain low. On Wednesday, only far eastern Mohave County
is included in the marginal threat area.

Temperatures through Tuesday will remain nearly steady, with
readings remaining 6 to 10 degrees above normal. Increasing cloud
cover from the approaching trough will spread northwest to
southeast across the area Wednesday. However, only northern
portions of the region will likely see slightly cooler readings,
and then by only 1 or 2 degrees.


.LONG TERM...Thursday through the weekend.

Models have a trough moving through the PacNW on Thursday, which
will flatten the ridge to our east and turn flow southwesterly. This
ushers in drier air, bringing an end to our first taste of the
monsoon. PoPs on Thursday become confined to far eastern Mohave
County, and are only 10-20%. By Friday, PoPs areawide drop to 5% or
less. As the aforementioned trough brings drier conditions, it will
also bring breezy southwest winds and slightly cooler temperatures
(albeit still above normal for the time of year). Forecast wind
gusts of 20-35 mph should yield at least elevated fire danger,
particularly in the lower elevations where fuels have cured and
afternoon RH values are expected to be around 8-12%.

As we head into the weekend, the southern US ridge begins to extend
westward into the Desert Southwest. As a result, winds weaken while
temperatures rise again. Based on the monthly temperature data thus
far and the latest model guidance, Las Vegas will be hard-pressed to
NOT experience its hottest June on record. A little number crunching
shows that even if the 5th percentile of high/low temperatures from
the NBM verify these last 7 days, we'll still set the record. At
this point, its not a matter of "if" but "by how much" we break the
warmest June record.


&&

.AVIATION...For Harry Reid...Winds will be primarily from the south
this afternoon with gusts of 15 to 20 knots. There is a low, but not
zero, chance of thunderstorm outflow winds from the south or east
affecting the terminal this evening. If this does not occur, typical
south southwest winds are expected overnight. Similar afternoon and
evening conditions are expected Tuesday, with a period of easterly
winds possible in the morning.

For the rest of southern Nevada, northwest Arizona and southeast
California...This afternoon, scattered thunderstorms are expected in
two areas - southeast of Interstate 15 and over the higher terrain
of Inyo and Esmeralda counties. On Tuesday, thunderstorm chances are
expected from Inyo and Esmeralda counties eastward through Lincoln
County and then south to Mohave County and the mountains of Clark
County. The main concerns with storms each day will be erratic gusty
winds and isolated ceilings below 8000 feet with associated terrain
obscuration. Away from storms, southerly winds gusting 15 to 25
knots are expected.

&&

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

&&

$$

SHORT TERM...Planz
LONG TERM...Woods
AVIATION...Morgan

For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter