Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 281643
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
843 AM PST Sat Feb 28 2015

.Synopsis...
A weather system is impacting California today with cooler and wetter
weather. Snow will impact travel in the mountains above 3500 feet,
and more so above 5000 feet. Showers dissipate on Sunday then a
second wave of wet weather arrives Monday.

&&

.Discussion...
Cold low pressure area is over the region. The main focus of
today`s shower and thunderstorm activity will be over the southern
half of the CWA...from around Oroville southward with isolated
showers and thunderstorms possible to the north. The bulk of the
activity will continue to be over the Motherlode and Sierra Nevada
with some showers and thunderstorms possible in the valley.
Thunderstorms will be slow moving today and should be producing
small hail. Wind shear is weak so storms will likely be on the
weaker side (non-severe).

Snow
levels will continue to be around 4000 feet today but in heavier
convective activity local areas may lower to around 3000 feet.
Thunderstorms may start to develop in the late morning to early
afternoon time period today. As the low shifts further to the
south late today and this evening the activity will shift further
south and focus on areas south of US-50. We could potentially get
up to 6 inches of new snow near the crest along I-80. Snowfall
amounts along highway 88 and areas to the south are expected to
pic up as the system shifts its focus to the south late this
afternoon and evening.

On Sunday shower chances will mainly be over the mountains with the
valley likely staying dry other than a stray shower chance over
the Northern San Joaquin Valley.

Another system dropping down from the north on Monday will bring
more shower and thunderstorm chances to the interior on Monday.
Snow levels look to be between 4000 and 5000 feet with this
storm.

&&


.Extended Discussion (Wednesday through Saturday)

Models trending drier for Tuesday as subsidence increases under
Northerly flow aloft. Dry weather with warmer temperatures
expected through Saturday as blocking ridge off the West Coast
builds inland. High temperatures in the Central Valley expected
in the upper 60s to lower 70s with mostly 50s to 60s for the
mountains and foothills.

By Monday, even though it is out of our official forecast range,
GFS/ECMWF both show the ridge shifting into the Great Basin and a
rather deep upper level Low progressing slowly eastward between
135W to 140W west of Oregon/NorCal.        JClapp

&&

.Aviation...

Mainly VFR conditions with mid to high level cloudiness expected
across forecast terminals over next 24 hours as upper low drops
south across central/southern CA today. Potential for isolated
aftn/evening thunderstorms with small hail. Have continued PROB30
group to cover this with low confidence of occurrence at any one
site. Winds will generally remain in the 5 to 10 kt range with a
few locally higher gusts. Dry weather and partially clearing skies
expected later overnight into Sunday as system moves south.


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 5000
feet in the west slope northern sierra nevada.

&&

$$







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