Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/20/18
Area Forecast Discussion
National Weather Service Las Vegas NV
800 PM PDT Thu Apr 19 2018
.SYNOPSIS...A cold low pressure system over the region will
slowly move away toward the Four Corners on Friday. Gusty winds will
decrease somewhat late this evening but north breezes will persist
through Friday. Scattered showers will diminish overnight then
linger near the southwest Utah border Friday. Dry and warmer weather
will return Saturday and hold much of next week.
.UPDATE...Scattered light showers and isolated thunderstorms
continue this evening in response to a closed low and cold
temperatures aloft passing through the region. Dozens of lightning
strikes occured earlier in the afternoon across Southern Inyo
County, most concentrated in the southern reaches of Death Valley NP
south of Telescope Peak. Lightning has since diminished but pockets
of light showers and sprinkles persist across Southern Nevada and
Suspect these showers will diminish in the coming hours with the
loss of daytime heating but widespread mid level cloud cover will
persist overnight. Winds continue to gust across our western zones
and I plan to maintain the current wind advisories through their
expiration at 11 pm. A few minor adjustments to the grids will be
sent out shortly mainly to account for current trends, but otherwise
most everything is in good shape.
.AVIATION...For McCarran...Breezy northwest winds have pushed
into the valley this evening with gusts to 25 knots. These winds
will continue through 05z before weakening. Another reinforcing shot
of northwest winds are expected tomorrow morning and by afternoon
winds are forecast to be between 010-030 deg with speeds 7-10 kts. A
few showers around the valley this will dissipate this evening with
mainly sct-bkn clouds around 8k feet overnight. Skies will remain
mostly clear on Friday.
For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty northwest to north winds will be seen across
Inyo, Esmeralda, and central Nye Counties with speeds between 20-35
kts these winds will diminish slightly overnight, but overall will
remain gusty overnight and Friday. A few showers and isolated
thunderstorms will be seen this evening, mainly north of I-40.
Showers and storms will diminish through the evening hours. Cigs
down to 5-6k feet are possible with lower cigs down to 3k feet in
heavier showers. &&
.SHORT TERM...through Saturday night.
Scattered light showers were apparent from radar returns around
southern Nevada and southeast California. A few lightning strikes
were detected over southern Inyo County and between Bicycle Lake and
Baker, but thunderstorms have been scarce over south central Nevada.
Widespread gusts over 40 mph were primarily observed where Wind
Advisories were in effect over the Western Mojave Desert and west
central Nevada. Brief bursts of wind over 40 mph have been observed
from Indian Springs down into the northwest Las Vegas Valley
associated with the showers, but these are expected to be short
lived. However, gusts in the 30s will continue through early evening
before winds begin to decrease.
Showers will diminish after sunset but the HRRR indicates Lincoln
County should see redeveloping showers over night as a disturbance
rotates down the back side of the exiting closed low. Eastern
Lincoln and northern Mohave counties will see lingering showers
Friday while the rest of the region is under a dry northwest flow
with high temperatures climbing 10-15 degrees. Some north breezes
will remain Friday night for areas prone to north winds but speeds
should generally be less than 15 mph.
Saturday will see temperatures climb an additional 3-5 degrees with
light winds most everywhere except maybe 10-15 mph along the lower
Colorado River Valley.
.LONG TERM...Sunday through Wednesday.
Confidence is still high on dry, breezy and warm conditions as we
head into next week. Operational runs of GFS and ECMWF continue to
show a shortwave trough moving across the Pacific Northwest on
Sunday then across northern Nevada Sunday into Monday. As the wave
passes to the north, breezy winds should develop Sunday and Monday
in response to surface pressure falls north of the region. Any
precip should be north of the forecast area.
During the Tuesday and Wednesday period the GFS and ECMWF solutions
show considerable differences in the synoptic evolution of a
shortwave trough. The GFS supports a progressive wave which quickly
dives south across California Tuesday and shifts to the east into
Arizona Wednesday. Whereas, the ECMWF suggests prolonged ridging
through at least Wednesday before a cutoff low off of the California
coast slowly tracks inland late next week. These patterns would
yield very different weather conditions: windy and cool under the
GFS solution and continued quiet weather and above normal
temperatures under the Euro. The extend forecast is favoring the
Euro due to run-to-run consistency, but forecast confidence after
Monday is very low.
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather according to standard operating procedures.
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