FXUS65 KVEF 260956
Area Forecast Discussion
National Weather Service Las Vegas NV
256 AM PDT Wed Sep 26 2018
.SYNOPSIS...Dry conditions along with well above normal
temperatures can be expected through the remainder of the week.
Temperatures will fall over the weekend into next week with breezy
afternoons expected this weekend. The weather pattern looks to
become more active the beginning of next as multiple systems may
affect the area.
.SHORT TERM...through Friday night.
A Rex Block pattern will set up Wednesday, pushing the negatively
tilted trough axis out of our area and allowing a high pressure to
our southwest to move in. This high pressure is expected to move
very little through the rest of the work week, allowing temperatures
to have another chance to reach the triple-digits. Dry conditions
and light winds will persist through the rest of the week.
.LONG TERM...Saturday through Wednesday.
Model consistency remains good over the weekend. Trough along the
California coast progged to weaken as it moves inland. Region will
be dry, breezy with temperatures finally heading in a downward
Forecast for early next week continues to be predicated on the
interaction of a northern stream trough and the remnants from what
was Hurricane Rosa. Tropical Storm Rosa is forecast to become a
hurricane today. The official forecast over the next 5 days has Rosa
curving northward and lying well west of the Baja Peninsula early
Monday morning. From there models continue to diverge. Latest ECMWF
now wants to phase the remnants of Rosa with trough deepening along
the West Coast. The remnant mid-level vorticity center moves
northward across eastern California/western Arizona next Tuesday.
This latest ECMWF solution looks very similar to last night GFS.
However, the latest GFS stalls the remnants of Rosa off the Baja
Coast Tuesday. However, with Rosa in the vicinity of the Baja
Peninsula both GFS and ECMWF depict a large area of high
precipitable water values pooling over the Gulf of California and
northwest Mexico. An incoming northern stream trough should induce a
gulf surge with PW values in excess of 1" spreading northward up the
Colorado River into eastern California, southern Nevada and western
Arizona. Dynamics ahead of this trough will be enhanced by a jet
streak crossing the area. GFS Ensemble QPF probability output is
suggesting an axis of highest probability across southeast
California, Colorado River Valley and western Arizona. So, I did
increase POPs a bit more in those areas. Again, much may change
before early next so continue to stay tuned.
.AVIATION...For McCarran...Light and variable winds expected through
the late morning hours before becoming northeast through much of the
day Wednesday. Speeds anticipated to remain under 8 kts. Winds will
return to a drainage pattern overnight. No operationally significant
cloud cover expected.
For the rest of southern Nevada, northwest Arizona and southeast
California...A backdoor cold front will allow for a stronger
northerly wind direction early this morning and through Wednesday.
Gusts upward of 20 kts expected down the Colorado River Valley,
which will taper off through the overnight hours. VFR conditions
expected through the period.
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
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