Scientific Forecaster Discussion
fxus65 kvef 230900
Area forecast discussion
National Weather Service Las Vegas Nevada
200 am PDT sun Sep 23 2018
Synopsis...afternoon breezes will return again today, then taper
off on Monday. Otherwise, dry conditions will prevail through the
middle of the upcoming week, and temperatures will remain several
degrees above normal.
Short term...through Tuesday night. Main feature early this morning
is a layer of thin clouds based around 12,000 feet mean sea level located
roughly from 29 Palms to Pahrump to South Cove to Vidal Junction.
The 00z models capture this as a thin layer of moisture centered
just above 700 mb, which is forecast to spread north during the day.
Beefed up cloud grids to account for this. As the low pressure
trough rolling through the Pacific northwest this morning crosses
The Rockies on Monday, the flow over our area will turn more
northwesterly and push the moisture out, leaving skies clear
areawide. This trough will also kick up afternoon breezes again
today, with speeds expected to be slightly stronger than yesterday,
but still below criteria for wind advisories or red flag warnings.
As the trough moves away tomorrow, gradients will collapse, and
winds will be weaker. A Rex block pattern begins to take shape over
the eastern Pacific Tuesday, bringing northerly flow and dry air
into our area. Temperatures will remain several degrees above
normal through the period.
Long term...Wednesday through Sunday.
The period starts out with a narrow, highly amplified ridge over the
western Great Basin, California extending northward into the Gulf of
Alaska. This ridge is sandwiched between a closed low over the
eastern Pacific and longwave trough over the central U.S. Models
agree closed low over the eastern Pacific will undercut the ridge
and slowly drift toward the northern California coast Thursday and
Friday. Model differences become greatest over the weekend regarding
trough depth and forward speed as it moves inland through northern
California and the northern Great Basin next weekend. Bottom line,
the region will remain unseasonably warm and dry Wednesday-Friday
with only a slight dropoff in temps next weekend. Breezes will
likely increase next weekend as well. How strong the winds get will
depend on just how deep the trough will be as it moves inland.
Aviation...for McCarran...southerly drainage wind becoming light
and variable around sunrise. By mid morning, a light east wind
should develop then shift to the southwest around noon. Sustained
southwest winds 10-15 kts, with gust 20-25 kts expected into early
evening before gusts subside. No operationally significant cloud
For the rest of southern Nevada, northwest Arizona and southeast
California...winds are expected to be light and variable this
morning. Southerly winds increase by early afternoon with sustained
winds generally 10-15 kts, with gusts 20-25 kts. Wind gusts should
subside in the early evening, the only exception will be around
kdag. VFR conditions expected through the period.
Spotter information statement...spotters are encouraged to report
any significant weather or impacts according to Standard operating