Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 190246
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
745 PM PDT Mon Mar 18 2024

.SYNOPSIS...Broad upper low over the region will keep chances of
afternoon showers through Tuesday evening across the Mojave Desert.
As this low pressure pushes east midweek, conditions will dry out
and temperatures will warm above seasonal averages. Another broad
area of low pressure will impact the region next weekend with the
return gusty winds, chances of precipitation and cooler
temperatures.
&&

.UPDATE...Mesoanalysis late this afternoon showed a cold core
upper level low situated over southeast California, which allowed for
weak instability to develop along with continued cyclonic flow aloft
associated with waves of better energy in the vorticity fields. This
resulted in scattered showers and thunderstorms developing, mainly
in southern Mohave County and south of the I-15 in Clark and San
Bernardino counties. Surface CAPE was able to climb to around 1000
K/Jg in parts of Mohave County where the most widespread
precipitation and impacts occurred. Occasionally heavy rain and
small hail were reported with some of the more organized
thunderstorms around Kingman, AZ as webcam images and spotters
reported isolated ponding on area roadways and nickle size hail.
Rain gages reported up to 0.50 inches of rain over the past 6 hours
in this region. Further north and west, precipitation was driven
more by forcing and thus precipitation was not as robust. That being
said, gusty outflow winds were able to develop in this region as
sunny skies allowed for the low levels to warm up and dry out
slightly compared to the past few days. A few locations reported
outflow gusts of 30 to 40 MPH in southern Clark County and the
Colorado River Valley. Outside of these areas, it was dry with mostly
sunny skies.

Instability has begun to weaken and radar has started to diminish in
terms of lightning and activity, as expected. However much like the
past few nights, continued waves of forcing moving east to west may
result in isolated showers through the rest of the night. Updated
precipitation chances to reflect this trend, trying to tie showery
activity to where the better forcing should be. Isolated showers may
persist through the night in southern Clark and southeast San
Bernardino counties. Not expecting impacts from these showers as
they should be fast moving and bring only light rain amounts. A
stray lightning strike is not out of the question, as suggested by
the latest HRRR, but again- not expecting widespread thunderstorm
impacts. Overnight, most areas will be dry and any precipitation
that may move through will be light and short lived. Winds will
continue to diminish as well the rest of the evening. Light winds
and low temperatures slightly warmer than last night can be
expected.
-Nickerson-
&&

.PREVIOUS DISCUSSION...253 PM PDT Mon Mar 18 2024
.DISCUSSION...A compact vort center over southeast California will
continue to drift south-southwest into northern Baja Mexico. The
feature will still be capable of producing showers and thunderstorms
as far north as the Morongo Basin into this evening. Elsewhere,
radar detecting isolated showers over the Coconino Plateau, east of
Mohave County. SBCAPE values of 500 J/kg being shown off the latest
SPC mesoscale analysis has been expanding over central Mohave County
over the past few hours. This area should fill in with showers and
isolated thunderstorms this afternoon. The HRRR does show some of
those showers and thunderstorms making it as far west as Clark and
eastern San Bernardino later this afternoon and evening. Isolated
showers possible overnight in parts of Mohave, Clark, and San
Bernardino Counties as models show additional vorticity centers
moving over the region as the cutoff low stays stationary near Yuma.

The cutoff low is finally progged to start moving east into central
Arizona Tuesday. However, lingering cyclonic flow and cold
temperatures aloft will provide another day of pop-up showers and
isolated thunderstorms mostly over Mohave County. But, can not rule
out a few as far west as Clark and San Bernardino Counties.

Dry and warmer weather returns to the region Wednesday-Friday under
a broad ridge of high pressure. Warmest temperatures of the year so
far expected. NBM currently has about a 40% chance that Harry Reid
International Airport will hit 80 degrees either Thursday or Friday.

Ensemble solutions showing a broad trough developing across the
western CONUS over the weekend into early next week. Main impact
looks to be strengthening south-southwest winds across the Mojave
Desert/far southern Nevada and northwest Arizona. Will also need to
keep a close eye on downslope potential in the lee of the southern
Sierra in Inyo County, and potentially the Spring Mountains. Chances
for precipitation begin to increase Friday night in western Inyo
County, eventually spreading east through parts of south central
Nevada Saturday. Depending on the eventual depth of the trough
precipitation chances should increase as far south as the mountains
of Clark and northern Mohave Counties. Temperatures slated to
retreat back closer to normal Saturday, then below normal Sunday and
Monday.

&&

.AVIATION...For Harry Reid...Breezy northeast winds this afternoon
with gusts around 20-25 knots anticipated. Wind direction expected
to remain between 030 and 060. In the late afternoon, showers are
expected to develop in the airport vicinity, with best chances to
the south and east. If any precip reaches the airport (10% chance),
it`s expected to be light. However, outflow from vicinity
precipitation should turn winds more easterly. East breezes and
vicinity showers linger through ~04z, possibly later, before drier
conditions prevail and typical southwest winds resume. East-
northeast winds return tomorrow, but much lighter than today. FEW-
SCT mid-level clouds persist through the TAF period, with bases
generally aoa 8kft.

For the rest of southern Nevada, northwest Arizona and southeast
California...Breezy northeast winds across most of the area today
with gusts around 20-25 knots. Winds weaken this evening and
overnight to less than 10 knots. Vicinity showers are possible at
sites in the Las Vegas Valley and Colorado River Valley, with the
best chance of precipitation at KIFP. Outflow from showers may
produce erratic, gusty conditions at KIFP and potentially KEED as
well. Cloud bases generally aoa 8kft. At KBIH, light and variable
winds today becoming northerly tonight.

&&

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

&&

$$

DISCUSSION...Pierce
AVIATION...Woods

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