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fxus65 krev 201040 

Area forecast discussion
National Weather Service Reno Nevada
240 am PST Wed Nov 20 2019


A low pressure system will bring much cooler temperatures along
with chances of valley rain and mountain snow into Thursday,
especially south of I-80. Light accumulating snow will occur
along the eastern Sierra from the Tahoe basin into Mono County
with some travel impacts especially over area passes. It will be
drier with a slow warming trend late week into the weekend.


Short term...

Latest WV satellite imagery showed an upper low dropping south
near or just offshore the central California coastline early this morning.
This is just a bit farther to the west than previous projected
paths and thus the deformation/precipitation band was still a
little north of previous expectations. Showers continued to
develop between I-80 and Highway 50 and move west into the Sierra
front and Tahoe basin with some light snow resulting in areas of
chain controls across higher passes. As such, precipitation has
been minimal farther south into Mono County so far.

The upper low is still forecast to continue its track south along
the California coast this morning and eventually turn east and begin to
fill later today. We expect the band of rain and higher elevation
snow to shift south into alpine-northern Mono-southern Lyon and
northern Mineral counties. Thus the best snow amounts above 6000
feet this morning are going to be mostly north of Bridgeport and
Hawthorne where several inches of snow are possible. Farther
south, including Highway 395 near Lee Vining and Mammoth and
Sweetwater Summit, snowfall amounts are going to be on the light
side for the morning. As the upper low moves south of the area
tonight, some models pivot additional precipitation west into
southern Mono County. So areas from Lee Vining south to Mammoth
could actually see bigger impacts tonight even though snow amounts
are only expected to be around an inch or two as the main axis of
precipitation will be just to the south.

Otherwise, showers will gradually taper late tonight into Thursday
with best chances south of Highway 50. Gusty northeast winds will
bring choppy lake waters today along with turbulence for general
aviation interests. It will then be mostly dry by Friday as high
pressure aloft nudges eastward into the region behind departing
upper low. Temperatures will be quite cool today and Thursday with
extensive cloud cover. The only places that may see some sun will
be north of I-80 across northeast California and far northwest Nevada. The
clouds will generally keep overnight lows from bottoming out
tonight but gradual clearing Thursday night will lend to much
colder overnight temperatures. Less cloud cover will allow
temperatures to warm Friday although the very cold start and
limited mixing will result in only a slight warming to near
seasonal norms. Hohmann

Long term...Saturday into early next week...

High pressure will close out the week with drier conditions, light
easterly breezes, and temperatures near seasonal averages.
Inversions will also likely redevelop through the weekend which may
produce hazy conditions down in the valleys.

As far as next week, the large scale pattern looks to favor a setup
for low pressure systems to drop in from the Pacific northwest. This
setup would feature colder, faster moving systems with less moisture
when compared to an atmospheric river type storm. However, these
systems can still result in significant travel impacts particularly
with a potential for lower snow levels and more widespread snowfall.

The first of these waves drops in on Monday but it looks like it
should miss US and pass to our east. Not expecting any precipitation
from this weak system but may see some breezy north winds develop.

The next low pressure system looks to be more organized with better
prospects for precipitation across the Sierra and western Nevada.
Timing on this one looks to be targeting the late Tuesday into
Wednesday timeframe. Being right around the heaviest traditional
travel days before Thanksgiving, impacts for travel could be
amplified. The operational GFS and European model (ecmwf) models are by far the most
aggressive in brining in a deep and cold low across region, however
ensembles show quite a wide range of solutions for midweek. Overall,
chances for seeing a system move through the area are increasing,
however it will just be a matter of how deep and cold it will be.
Have increased precipitation chances as a result. The timing details
and precipitation amounts will come into better focus over the next
several days so if you have travel plans for the Thanksgiving
Holiday, keep close watch on the forecast. Fuentes



Krno and kcxp: band of showers will continue to impact krno and kcxp
through this afternoon and into early evening with a better
potential at kcxp. 30% chance of showers for krno and 50-60% chance
for kcxp. Snow levels expected to remain above 5000 feet, so rain is
expected but a brief rain/snow mix not out of question mainly across
kcxp where better potential exists for heavier bands of showers.
Expect periods of MVFR ceilings/visibility.

Ktrk and ktvl: chances for snow showers will continue through this
afternoon with about 25% chance for ktrk and 40-50% chance for ktvl.
Periods of IFR/LIFR conditions and mountain obscuration are
possible. Gusty northeast to east winds will develop across the
Tahoe basin with areas of turbulence developing along and west of
the Sierra with gusts of 50kts possible along the ridgetops.

Kmmh: chances for snow showers near the airfield are most likely
after 17z with a better potential this evening after 03z. Periods of
IFR/LIFR conditions possible in heavier Showers. Mountain
obscurations likely. Showers will decrease late Wednesday with
lingering showers through early Thursday morning. Fuentes


Rev watches/warnings/advisories...
Nevada...Winter Weather Advisory until noon PST today above 6000 feet in

Lake Wind Advisory until 3 PM PST this afternoon for Lake Tahoe
in nvz002.

Winter Weather Advisory until noon PST today nvz001.

California...Winter Weather Advisory until noon PST today above 6000 feet in

Lake Wind Advisory until 3 PM PST this afternoon for Lake Tahoe
in caz072.


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