Area forecast discussion
National Weather Service Reno Nevada
233 am PDT sun may 19 2013
Synopsis...
High pressure will build into the area today into Monday with
mild and dry conditions. A low pressure system approaching the
West Coast will bring strong winds to the area Tuesday, with gusty
conditions lingering into Wednesday. As this low pressure settles
over northern California and Nevada, cooler conditions are likely
with showers possible later in the week.
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Short term...
Exiting shortwave is keeping isolated showers across portions of
north central Nevada early this morning. As the shortwave
continues eastward a drier and more stable air mass is working
into the region care of an expanding area of high pressure over
the West Coast. An easterly gradient sets up between these two
features, with enough of a thermal gradient over the Sierra by
Sunday night to induce stronger easterly winds in the Tahoe basin
through Monday morning. Generally wind gusts appear to remain
around 25 mph, and therefore no lake wind advisories are planned
at this time. The easterly gradient will limit the warming
potential today, with highs remaining near average.
Ridge axis moves overhead on Monday bringing warming and
additional drying to the region. There is a fairly pronounced dry
slot Monday morning and expect that between this and the lingering
easterly winds, humidity recoveries on midslopes will be fairly
poor. Gradient weakens Monday afternoon, with light winds expected.
A deep, cold area of low pressure begins to drop south out of the
Gulf of Alaska Tuesday, backed by a 110 knots jet. This will induce
strong thermal and pressure gradients across northeast
California, the Sierra, and western Nevada on Tuesday. Have
continued the trend of raising wind speeds across the region, but
these may need to even be bumped up further depending on how the
trend of this low progresses in future model runs. This will be
the main weather maker in the long term period. See below for
additional details. Df
Long term...Wednesday through Saturday...
Models in better agreement this morning with the upper low to affect
the western U.S. Later this week. The GFS/ec/Gem all in line with
dropping the low southward and just north of the California/Nevada border for
Wednesday into Thursday. This positions is closer to the ec runs of the past
few days, but of note, all the models are actually cooler with temperatures
Wednesday/Thursday than even the ec was yesterday. With the better model
agreement, moderate confidence in the extended forecast although
would not be surprised of small changes in the next couple days.
Have cooled off temperatures Wednesday/Thursday with better model agreement in the 50s
for the Sierra and 60s for western Nevada. Also, with the low tracking just
north of the Sierra and western Nevada have increased probability of precipitation a bit. Added a
slight chance near the Oregon border Wednesday and brought a slight chance
further south on Thursday. Snow levels could drop as low as 6000
feet toward Susanville with the latest forecast. Winds will be less than
Tuesday both days but locally breezy with some gusts up to 30 miles per hour at
times.
For Friday/Sat, models pull the main low off to the northeast, but
differ on how much of a hang back trough remains. GFS has a stronger
trough and is also cooler. Despite the model differences, temperatures will
moderate back to near average for next weekend. While there could
also be a stray shower or two, have left the forecast dry with
little forcing indicated on any of the models, including the GFS.
Wallmann
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Aviation...
Generally VFR conditions this morning with a few showers over
Pershing/Churchill counties. Expect showers to move east by 13z. As
for terminals, expect north winds near 10-15 kts today with VFR conds.
Winds to weaken tonight for terminals but will keep going a bit from
the NE over the Sierra ridges. Could be localized low level wind shear and
turbulence near Lake Tahoe, but otherwise do not expect much impact
from these winds. A stronger SW wind event is possible late Tuesday.
Wallmann
&&
Rev watches/warnings/advisories...
Nevada...none.
California...none.
&&
$$
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