Scientific Forecaster Discussion
fxus65 krev 221125
Area forecast discussion
National Weather Service Reno Nevada
325 am PST Fri Nov 22 2019
Dry conditions with a warming trend are expected through this
weekend with limited ventilation due to inversions. An active
weather pattern is likely next week with colder storm systems
bringing periods of snow, even in lower valleys, which will
produce impacts for Thanksgiving Holiday travel. The highest snow
chances are anticipated from late Tuesday into Wednesday.
Quiet weather will prevail today through this weekend as high
pressure builds into CA-NV. Lingering cloud cover mainly south of
Reno and over the eastern Sierra is finally expected to dissipate
during the day today, although with light winds and limited mixing
there could be patches of persistent stratocumulus for some
locations through the afternoon. Only minimal cloud cover is on
tap for Saturday and Sunday, while temperatures edge upward
through the 50s for most areas. By Sunday, portions of eastern CA,
the Tahoe basin and far western Nevada could reach 60 degrees. Mjd
Long term...Monday through next weekend...
* a significant winter storm is anticipated to impact the Sierra
and western Nevada Tuesday afternoon through Wednesday. We
continue to increase the snow chances and amounts with better
model agreement. Periods of light snow may continue into Friday.
* This will be a cold system with snowfall for both the Sierra and
all valley floors in western Nevada.
* Being that this is a very busy Holiday travel period,
significant travel delays are possible with any amount of snow.
Please monitor the latest forecasts and plan ahead if you have
travel plans for Thanksgiving.
Monday continues to be quiet and will be the best travel day. The
ridge will flatten with colder air filtering in as a wave moves
through the northern rockies. Clouds will increase Monday night
into Tuesday morning ahead of the main event.
GFS/ec and their respective ensembles all show a deep, cold upper
low dropping down the coast. The forecast pattern has many
similarities for large snowfalls in the Sierra and much of western
Nevada. However, it looks to be more progressive at this time so
amounts, while likely significant, do not look extreme.
Snow looks to begin Tuesday afternoon in the Sierra, with it
spreading eastward into Nevada Tuesday night. The heaviest snows
look to move south of the area by Wednesday evening. While amounts
are still to be determined, for 24 hours ending Wednesday
afternoon, ensembles are showing a 60-70% of 2+ inches along the
Sierra front of western Nevada. There is also a 60-70% chance of
at least a foot for the Sierra crest.
Ensembles now show a high likelihood of the upper low dropping
down to Southern California for Thursday afternoon, remaining
there into Friday. While this will keep the heaviest snow south of
the region, snow showers are likely to continue each day. One
thing to watch will be to see just how far south it drops. If it
remains farther north, more snow is likely to occur with the
better chances for Mono and Mineral counties at this time.
The low pulls away over the weekend, but it will remain quite
cold. Depending on snow cover, colder valleys may drop below zero
with highs possibly stuck in the 20s and 30s. There may be another
system dropping in from the north late Sunday, but ensembles are
showing the biggest impact to the north at this time. X
Stubborn low clouds continue across the eastern Sierra with MVFR
ceilings from ktvl south to kmmh with mtn obscuration. These clouds
will continue through 16z, then slowly break up and become VFR by
19z. Outside of this area, VFR conditions prevail through today,
but some afternoon cumulus will develop with bases near 4000 feet.
We are not expecting any consistent ceilings with these clouds, but
there is a 20% chance a deck could form for the Sierra front
terminals (krno, kcxp, kmev).
VFR conditions likely tonight and through the weekend with light
winds from the northeast. A significant winter storm is still in
the cards for late Tuesday into Wednesday with snow showers
possible through Friday. Snow accumulations are possible for all
terminals for the Tuesday night and Wednesday time period. X