FXUS65 KVEF 250512
Area Forecast Discussion
National Weather Service Las Vegas NV
1012 PM PDT Sat Aug 24 2019
.SYNOPSIS...Weather concerns will shift from afternoon breezes
over the weekend to excessive heat early to mid-week next week.
Moisture may begin increasing once again towards the end of the
Quiet weather is in store for the remainder of the weekend as high
pressure strengthens over the local area. Gusts have died off this
evening but are expected to resume once again Sunday afternoon in a
similar fashion to today with gusts of 15 to 20 mph possible. Temps
will begin to rise Sunday into the beginning of the upcoming work
week which will allow heat to remain the primary weather concern
Monday through Wednesday.
PREV DISCUSSION 237 PM PDT Sat Aug 24 2019
.DISCUSSION...Despite weak surges of low-level moisture and modest
surface-based instability, conditions are calm, mostly clear skies
and relatively light winds.
Ridging has started to build in overhead this afternoon. This has
warmed temperatures aloft, capping instability along the Colorado
River. These warm, capping temperatures are expected to strengthen
as the ridge expands further southeastward over the next couple of
days. Under ridge influence, temperatures at the surface will
increase a few degrees each day through Tuesday, approaching near
record temps across the Mojave Desert by Tuesday afternoon. Due to
uncertainty in the near-surface moisture, held off on hoisting any
heat headlines for now. Outside of extreme heat concerns, the
forecast remains benign in terms of convective activity and winds.
By midweek the forecast becomes slightly more complex. Extended
ensemble guidance remains fairly consistent with previous runs,
resolving a moisture surge in response to a tropical disturbance
south of Baja California in the Wednesday/Thursday timeframe. With
an increase in moisture, chances for thunderstorms across portions
of the Mojave Desert will start to increase while temperatures would
cool. However, a similar surge was also noted during the developing
stage of tropical storm Ivo, which did not materialize.
Forecast uncertainty increases further after Wednesday due to low
confidence in the position of subtropical ridge. Ensembles indicate
it may wobble westward and eventually overhead. Under this scenario,
another spike in temperatures is likely -- possibly to dangerous
levels -- along with suppressed convective activity.
.FIRE WEATHER...Dry and hot conditions along with periods of breezy
winds, especially across the southern Great Basin are expected
through the rest of the weekend. Winds will be calm early this week
as temperatures increase. Critical to near critical humidity with
poor overnight recovery (less than 35%) is expected through at least
Tuesday. Moisture may increase later this week, resulting in
increasing thunderstorms chances across the Mojave Desert,
especially over higher terrain.
.AVIATION...For McCarran...Wind speeds will gradually
diminish overnight and remain generally light Sunday morning. Winds
may once again turn east to southeast with speeds around 8-10 kts
after 16z and gradually turn more southerly in the afternoon. No
operationally significant clouds expected.
For the rest of southern Nevada, northwest Arizona and southeast
California...Minimal impacts expected overnight and through tomorrow
morning. Some minor wind gustiness out of the south-southeast is
possible tomorrow afternoon across the Las Vegas Valley and KBIH but
nothing major. Skies will be mostly clear and no precipitation
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
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