Area forecast discussion
National Weather Service Reno Nevada
208 PM PDT Sat may 25 2013
Synopsis...
low pressure will remain over the Pacific northwest through Sunday
then move inland on Memorial Day. The low will produce gusty
afternoon and evening winds across the eastern Sierra and western
Nevada with a few showers and thunderstorms north of Susanville
and Gerlach Sunday. The chance for showers increases on Memorial
Day, with light snow possible in higher elevations of the Sierra.
&&
Short term...
Next piece of energy rotating around the low off the Pacific
northwest coast will pass over northern California and far
northwest Nevada late tonight and early Sunday morning. Isolated
showers remain possible north of Susanville-Gerlach. Thunderstorm
potential is low due to lack of instability, but lift from a jet
segment over northern Washoe tomorrow afternoon could counteract
the low instability.
Gusty winds this evening will diminish by 10pm, but will return by
late morning and early afternoon Sunday. Peak gusts will remain
near 30 miles per hour in the Tahoe basin and at 30-35 miles per hour gusts along
Highway 395 from Susanville through Reno-Carson and down into Mono
County. Winds will create rough conditions on area lakes,
especially pyramid, lahontan, Topaz, Bridgeport, and Crowley.
Waves on Tahoe could kick up as high as 3 feet.
Models have remained consistent with the trough moving inland for
Memorial Day, and thus confidence is higher in showers for the end
of the Holiday weekend. A 1-1.5 inch of precipitable water over
the Pacific will reach northern California in the morning. The
increased moisture along with the trough and upper jet will
produce showers north of Portola-Gerlach by middle morning, with
showers spreading south and east into the Tahoe basin and western
Nevada by middle to late afternoon. Rainfall amounts of 0.25 to 0.50
inch is possible in the northern Sierra and Lassen County, with
amounts less than 0.15 across western Nevada.
The dry air in place over the Tahoe basin and Mono County could
push snow levels down to near 8000 feet once the showers start,
but do expect snow levels to remain at 8000-9000 feet for most of
the event. The greatest chance for accumulating snow on roads are
Carson, ebbetts and Sonora passes, where an inch or two of slush
could create difficult driving conditions. Farther south, showers
may not reach Tioga Pass to Mammoth Mountain until early Monday
evening. An inch or two of snow that far south is not out of the
question, but confidence is not as high as the track of the system
is a bit farther north. Brong
Long term...Tuesday through Saturday...
A negative-tilt trough will provide moisture and instability for
scattered showers Tuesday especially over the Sierra and north of
Highway 50. Afternoon heating Tuesday will create instability
below about 10,000 feet but above that level the trough does not
look cold enough to create steep lapse rates. As such, the Tuesday
afternoon convection is not expected to be deep enough for
thunderstorms. Tuesday night a northwest-to-southeast oriented jet
across the Pacific noses into Nevada. This pattern should decrease
the threat for showers away from the Sierra and create breezy
winds Wednesday afternoon. Will keep chance probability of precipitation over the far
north for Wednesday as well and keep temperatures below average.
Northwest flow continues into Thursday with some drying and a weak warming
trend. For Friday and Saturday numerical model solutions show a
large spread of solutions regarding the development of a weak ridge
offshore and possibly a weak trough over the western U.S. The
model consensus is for relatively weak flow aloft and dry
conditions Friday and Saturday but forecast confidence is on the
low side. Offshore ridging could shift east faster and provide
significant warming by Friday...or below average temperatures could
extend through the entire week. Jcm
&&
Aviation...
Low pressure remains over the Pacific northwest with surface gusts
of 25-30 kts through 04z. A few showers over northern Lassen and
Washoe counties will dissipate by 03z.
Afternoon and evening winds will return Sunday, with peak surface
gusts near 30kts. There is a slightly higher chance for showers
and thunderstorms north of Susanville-Gerlach after 20z Sunday.
For Monday a trough will move into northern California with
showers developing over northeast California in the morning.
Showers will spread south into the Reno-Tahoe-Carson area during
the afternoon. Conditions could drop to MVFR in the Sierra,
primarily due to lowering ceilings. Brong
&&
Rev watches/warnings/advisories...
Nevada...none.
California...none.
&&
$$
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