Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Reno Nevada
154 am PDT Sat Apr 25 2015
rain and snow will decrease this afternoon as low pressure moves
into eastern Nevada. High pressure will build over the Sierra and
western Nevada on Monday with afternoon highs warming into the
70s and 80s for middle week.
Quick moving, but very dynamic system is moving through the
Sierra and western Nevada early this morning. A period of moderate
to heavy precipitation will impact the region south of Susanville
to Lovelock as a coupled cold front and jet forcing pass overhead.
There is plenty of instability to go along with the lift, so
embedded thunderstorms south of I-80 and enhanced snowfall rates
of up to 2 inches per hour in the Sierra are possible. Snow
levels have been fluctuating with the convective activity and
could fall as low as 5000-5500 feet.
Snow totals along the crest south of Highway 50 could exceed 12
inches, while most of the passes received 6-12 inches. Do not
think there will be widespread travel impacts for western Nevada,
outside of the Carson Range passes and the Virginia Highlands.
Once the front and trough axis passes, moisture depth and lift
greatly decrease. Though instability will linger allowing low
topped convective showers to continue through the afternoon. This
will decrease the potential for accumulating snow, especially on
roads with the late April solar flux. Moderate to heavy showers
will likely end by late morning, which suggests the Winter Weather
Advisory may be dropped by 10 am. Gusty northwest winds are also
possible later today, which will lead to choppy conditions on
Pyramid Lake this afternoon.
Conditions will dry starting this evening with a cold north
flow through Sunday. This will keep afternoon highs in the low 60s
for western Nevada with 50s for the Sierra. High pressure will
move back over the Sierra by Monday, with warm and dry conditions
into Tuesday. Brong
Long term...Tuesday through Saturday...
no significant changes were made to the long term forecast. Overall
expect dry conditions with above normal temperatures for the first
part of the week. High temperatures will be in the upper 70s to middle
80s for western Nevada valleys and the upper 60s to middle 70s for the
Sierra valleys on Tuesday and Wednesday.
High pressure across the Sierra and western Nevada begins to weaken
on Wednesday as a trough pushes into the Pacific northwest. Typical
afternoon Zephyr winds are expected on Tuesday and Wednesday
afternoons with wind gusts around 30 miles per hour.
Models begin to diverge by late Wednesday into Thursday with the
position of the trough pushing into the Pacific northwest. GFS model
runs have remained consistent with bringing the trough and a cold
front with it further south across Nevada. The European model (ecmwf) has also
remained consistent with keeping the trough much further north, with
little to no impacts. The GFS solution would result in much more
breezy and chilly conditions, while the European model (ecmwf) would be breezy, but
not quite as cold. The GFS solution would also bring increased
chances for precipitation across far northern Lassen and northern
Washoe counties for Thursday-Friday. There is enough disagreement
between the operational forecast models that I made little change to
the second half of the week and left in the slight chance of showers
Thursday night north of Susanville and Gerlach for now. Weishahn
showers have already begun to affect the Sierra terminals with a mix
of rain and snow at both ktrk and ktvl. Conditions will continue to
deteriorate through the morning as the bulk of the precipitation
with the storm pushes in between 9-12z. Widespread terrain
obscuration for the Sierra and northeast California can be expected
through the day. Light accumulations of snow are possible on runways
at ktrk/ktvl this morning, with rapid melting on runways by late
morning with the more intense late April sun. Snow will push into
kmmh around 12z, but as the quick moving system pushes out it should
limit snow accumulations on the runway there.
For western Nevada...rain will impact the Lower Valley terminals
through the morning with the main impacts from terrain obscuration,
periodic MVFR ceilings and turbulence. Another round of precipitation
may develop on the backside of the system bringing a band of showers
through the Interstate 80 corridor between 18z-0z. Weishahn
Nevada...Winter Weather Advisory until 2 PM PDT Saturday nvz002.
California...Winter Weather Advisory until 2 PM PDT Saturday above 5500 feet
Winter Weather Advisory from 5 am to 5 PM PDT Saturday caz073.
Winter Weather Advisory until 2 PM PDT Saturday caz072.
For more information from the National Weather Service visit...
http://weather.Gov/Reno (all lower case)