Area Forecast Discussion
Issued by NWS Reno, NV
FXUS65 KREV 262209
Area Forecast Discussion
National Weather Service Reno NV
309 PM PDT Wed Oct 26 2016
Two wet storms will affect the Sierra and western Nevada at the
end of the week through the weekend. The first storm on Thursday
night into Friday is warm and wet with the second storm Saturday
night into Sunday being colder. An active pattern will continue
into next week.
Two wet storms are going to affect the Sierra and western Nevada
the end of the week and through the weekend. The first storm of
significance will be Thursday night into Friday and will be warm
and wet, with subtropical origins. Heavy rain with snow above
9,500 to 10,000 feet will fall in the Sierra with the peak of the
heaviest rainfall likely to be Friday morning and afternoon. Snow
totals above 10,000 feet are expected to reach 6 to 12 inches.
Favorable dynamics and isentropic lift will allow for plenty of
spillover into Western Nevada. The Friday morning commute is
likely to be slow going in most locations.
Models are improving in their consistency with QPF amounts, and
will continue to trend the forecast numbers toward the higher end
of guidance. The subtropical origins will favor efficient rainfall
processes and PWAT numbers are approaching late October maximums.
In addition, the envelope of ensembles continues to trend upwards
with impressive plume values. Forecast soundings are indicating
decent instability and forcing, with some even hinting at the
potential for isolated thunder Friday. Will leave thunder out of
the forecast for now, but it may need to be added if parameters
continue to look better. The possibility of embedded convection
could lead to higher rainfall rates.
The greatest concern will be rapidly accumulating rainfall causing
flash flooding and/or rock slides and debris flows in areas of
steep terrain and across recent burn scars. Anyone with interests
near the Emerald, Little Valley, or Marina Fires should be
prepared. River rises are likely, but mainstem river flooding is
not expected. Small streams and roadways with poor drainage (or
drains blocked by leaves) could see minor flooding.
Light, warm advection driven rain will continue in the Sierra and
northeast California on Saturday. Some sprinkles are possible
into western Nevada. This will be followed by the second storm
Saturday night into Sunday. This storm is colder with snow levels
starting around 7,000-8,500 feet Sunday morning, lowering to
6,500-7,000 feet by Sunday afternoon. They may lower further in
the heaviest precipitation bands and also Sunday night as colder
air works into the region. Most all Sierra passes will be impacted
by periods of snow Sunday into Sunday night, including Highway 395
in Mono County. It is best to prepare for travel delays, chain
controls and winter conditions if your travel plans take you in
the Sierra Sunday. The biggest question remains if snow will
accumulate at Lake Tahoe level. At this point it appears just a
light dusting will be likely Sunday evening, with the main
accumulation limited to areas above 6,500 feet. Snow totals may
reach 8 to 18 inches above 7,000 feet in the Sierra.
Rain will once again spillover into western Nevada with this
system, but totals are not expected to be as high as the first
storm. Winds will be gusting 80 to 90 mph across Sierra ridges,
with 30 to 35 mph gusts in valley locations.
Advice: If needing to travel, the best window will be from roughly
Friday night through Saturday afternoon with just lingering rain
.LONG TERM...Monday through Wednesday...
The ensemble of model simulations shows a bit of a break between
storms Monday and then differ widely on the timing, amplitude and
track of the next system which could arrive Tuesday or Wednesday.
Prior to the next system, there could be a couple degrees of warming
Monday afternoon and showers may linger Monday-Monday night north of
U.S. Route 50. Snow levels could be 6,000 to 7,500 feet MSL north of
I-80 and 7,000 to 8,500 feet south of I-80. Heavy snow is not
expected but these showers could at times create slick
stretches across roadways. JCM
Wind gusts 15-25 kts will continue at terminals through this evening
and are likely again tomorrow afternoon and evening. Sierra ridgetop
winds will remain windy tonight and then increase tomorrow to peak
gusts of 45 to 60 kts. A wet/warm storm moves in late tomorrow
through Friday with increasing clouds, moderate to heavy rainfall
and restrictions to CIG/VIS likely. Another storm is set to move in
this weekend with additional impacts to aviation as well. JCM
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