Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Las Vegas Nevada
247 PM PDT Wednesday may 6 2015
Synopsis...increasingly breezy conditions will develop through
Thursday as a strong and cold low pressure system begins to move
toward Southern California and southern Nevada. Showers and
thunderstorms are possible area wide Friday as the low moves over
the region with temperatures well below normal. Dry and warmer
conditions are expected Sunday into early next week.
Short term...through Friday night.
The cold low pressure system currently over the Pacific northwest is
still on track to dive down through California Thursday then swing
across southern Nevada Friday. The latest models remain fairly
consistent with the track and timing of the system and generally
support the inherited forecast trends with no big changes needed.
Thunderstorms were firing over eastern Nye and Lincoln counties this
afternoon associated with a middle level convergence zone. This zone
should shift over north central Nevada overnight in response to the
closed low center diving into northern California. As the cold core
digs over central California Thursday...this will place Inyo and
Esmeralda counties close to the eastern side of the core through
Thursday afternoon then the low center is forecast to track directly
across the southern Sierra and over southern Nevada Friday. This
will lead to significant snowfall in the southern Sierra and a
Winter Weather Advisory has been issued above 6000 feet. The other
impact of the system will be gusty south to southwest winds across
much of the region Thursday afternoon and evening. Gusts of 30 to 40
miles per hour will be common but advisory level winds look marginal and it
does not appear to have the potential of producing widespread
blowing dust so no wind advisories are planned for now.
Scattered to numerous showers and thunderstorms will occur across
the rest of the region Friday through Friday evening but confidence
is low in significant snowfall for the Spring Mountains so no other
advisories are planned for now. High temperatures could be the
coolest since early March with readings in the low to middle 60s
expected in Las Vegas Friday.
Long term...Saturday through Tuesday.
Even as main low shifts east into The Four Corners region Saturday,
models insist additional energy moving south within backside of
trough will keep a chance of showers and a few thunderstorms across
mainly southern Nevada and Inyo County Saturday. For Sunday, any
remaining instability will confine isolated showers to eastern
Lincoln and northern Mohave counties. Dry/stable air mass associated
with ridging will start building in from the West. Ridge quickly
shifts east Monday as winds aloft back southwesterly on Tuesday
ahead of next trough developing near the Pacific northwest coast. There is some
spread in the positioning of this next trough. After the dramatic
cool down Friday, temperatures will steadily warm during the period
returning to normal or slightly above normal Monday and Tuesday.
Aviation...for McCarran...gusty southwest winds through the
remainder of the afternoon. Winds will decrease somewhat overnight
but occasional gusts to 20 kts will be possible. Very similar
conditions are expected Thursday. Clouds around 10-15k feet will be
possible over the terrain both days with scattered-broken higher clouds
through the period. Shower activity mainly in the mountains may
cause erratic wind shifts Thursday.
For the rest of southern Nevada...northwest Arizona...and southeast
California...scattered showers and thunderstorms possible across the southern
Great Basin and Inyo County into this evening. Gusty surface winds
and locally strong updrafts possible near convection. South to
southwest winds of 15-20kts with gusts to 30kts after 18z expected
across the area. Similar conditions are expected Thursday with
increased shower/tstorm activity mainly northwest of Interstate 15.
Spotter information statement...spotter activation is not expected
at this time however...spotters are encouraged to report any
significant weather conditions this week according to Standard
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