Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Las Vegas Nevada
839 am PDT Thursday Jul 24 2014
Synopsis...high pressure will remain centered near The Four Corners
area through early next week. Flow around the high will bring a
gradual increase in moisture with thunderstorm chances spreading
from northwest Arizona today and Friday up into most of the Mojave
Desert and southern Great Basin by Sunday. After another hot day
today...temperatures will cool some as moisture increases.
Update...forecast trends look reasonable this morning. No update
planned at this time.
242 am PDT Thursday Jul 24 2014
Short term...through Saturday night...strong high pressure will
remain centered near The Four Corners area during the short term.
Flow around the high will bring a gradual increase in moisture.
Isolated thunderstorms are expected over portions of Mohave County
this afternoon...spreading into the higher elevations of Clark and
eastern San Bernardino counties Friday afternoon. The models are in
pretty good agreement spreading moisture farther north into Lincoln
County Saturday so I increased probability of precipitation over the higher terrain there.
The western half of the forecast area looks to remain dry and stable
even Saturday. Another very hot day is expected today with high
temperatures close to what was seen Wednesday. Models indicate
slightly lower heights and 700 mb temperatures so we may be a degree
cooler. High temperatures should cool several degrees for Friday and
Saturday due to the increase in moisture and cloud cover.
Long term...Sunday through Thursday...high pressure ridge centered
over the southern rockies will result in a southerly flow across the
region with a modest increase in monsoonal moisture expected. While
this will not be a significant moisture surge, enough instability
will be present for isolated to scattered storms originating in the
mountains and possibly drifting into the lower terrain later in the
Low level moisture remains fairly limited for late July which
will keep instability parameters from getting too out of hand, but
bufr soundings for Las Vegas do show some weak instability
supporting a slight chance for storms on Sunday and
Monday...especially if we can get an outflow collision or two.
Therefore I expanded the slight chance of thunder to include the
valleys of Clark...eastern San Bernardino and Mohave counties for
Sunday and Monday. By Tuesday the high pressure ridge will be
located closer to Arizona resulting in another downturn in
The increased cloud cover will keep temperatures down closer to
seasonal normals Sunday Onward...while slowly rising a few degrees
above normal by midweek as things dry out again.
Aviation...for McCarran...prevailing south to southwest winds will
persist through Friday. A light southeast wind may briefly favor
runway config 4 during the middle to late morning hours. There will be
a slight chance of thunderstorms each afternoon and evening in the
Peach Springs and Mormon Mesa corridors and also over the Spring
Mountains and Sheep Range by Friday afternoon.
For the rest of southern Nevada...northwest Arizona...and southeast
California...afternoon thunderstorm chances will be limited to
Mohave County today but may spread into the mountains of Clark and
eastern San Bernardino counties by Friday afternoon.
Elsewhere...mostly clear conditions can be expected with daytime
south to southwest winds of 10 to 20 knots.
Spotter information statement...spotter activation is not expected
at this time. However...spotters are encouraged to report any
significant weather conditions according to Standard operating
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