National Weather Service Forecast Discussion

			


000
fxus65 krev 102316
afdrev

area forecast discussion
national weather service reno nv
315 pm pst wed mar 10 2010


.short term...

high pressure is building into the area in the wake of a low moving
east out of nevada. brisk north winds will continue into this
evening...tapering off after sunset. minimum temperatures will be 5
to 10 degrees below normal tonight with dissipating cloud cover. as
the ridge builds into thursday...temperatures will have a chance to
warm nicely with valley temperatures reaching the low 50s with light
wind.

the next system approaching from the west will first hit with a
round of gusty winds followed by rain/snow in the sierra and points
east at the end of the work week. late thursday night into friday
morning southwest winds will increase across the sierra and into
western nv. sierra ridge top gusts could reach near 100 mph through
the day friday as valley and western nv winds gust upwards of over
40 mph at times. most recent nam bufr soundings hint at a stable
layer forming just over ridge level which indicates the potential
for a downslope wind pattern. with the southwest wind direction
favoring this type of event...will need to keep a close eye on
future model runs to see if this could be a possibility.

the moisture plume is expected to arrive to the sierra slightly
ahead of the cold front on friday morning...meaning valley rain and
mountain snow during the day friday with snow levels around
6000-7000 feet north to south. the snow/rain will begin early friday
morning in lassen and plumas counties and move southward through
the day. by friday night the cold front catches up to the
moisture...dropping snow levels and providing a good amount of
forcing along the sierra...especially over the tahoe basin. this
will be the best chance for heavy snow with the greatest
accumulations occurring overnight. exact timing of the peak snowfall
still needs to be ironed out as timing differs slightly...with the
gfs about 3-6 hours faster than the nam and ecmwf. have trended
towards the nam and ecmwf solutions for now. the snow is expected to
taper off saturday morning as dry air moves in behind the
front...with the exception of mono county where snow showers will
continue through the morning as the remnants of the moisture plume
continue to move southeast.

overall high confidence that friday night into saturday will produce
a decent snow event in the sierra especially in the tahoe basin
where advisory level snow amounts are likely above 7000 feet. with
the moisture fizzling into mono county...amounts will be less but
could still be worthy of an advisory. have issued an sps to further
explore potential impacts of this system. western nevada  will most
likely see rain at the lower elevations...as most of the moisture
has moved southeast by the time the cold front moves in...limiting
snow amounts. labelle

.long term...sunday through wednesday...

ridge to build into the region sunday in wake of departing low
for significant warming trend. ridge axis to shift over the sierra
monday with temps jumping into the mid 60s in wrn nv valleys with
clear skies and light winds. ridge axis to shift east of the forecast
area tuesday as a trough approaches the west coast. still a mild day
expected with some increasing high clouds and gradual strengthening
southwesterly winds.

a low is expected to move through the pac nw and approach the area
wednesday although models and ensembles differ on track. ec brings
it much further south and tries to split it over nv and ca while
gfs is much more progressive shifting it toward nrn rockies. it
doesnt look like much of a precip maker so main effect on which
model comes to fruition will be how much cooler we get wed into
thursday. will need to keep an eye on instability wed but more so
thurs as mild temps ahead of the approaching trough with weak
forcing aloft could lead to some buildups and possible isolated
showers or storms. milne
&&

.aviation...

high confidence that north flow will continue at all terminals
through this evening. wind gusts will taper off after 03z. vfr
conditions through the taf period with dry air moving in after 00z.

next system to reach the northern sierra friday afternoon.  strong
flow over the ridges should generate mountain waves and surface
gusts 35-45kts.  period of heavy snow likely for ktrk and ktvl
friday afternoon into friday night...with chance of rain or snow at
krno. labelle

&&


.rev watches/warnings/advisories...
nv...none.
ca...none.
&&

$$

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