Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 051233
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
433 AM PST Wed Mar 5 2014
A system is beginning to spread rain into northern California,
with the bulk of precipitation coming later today and early Thursday.
Breezy to windy conditions expected late this afternoon and through
the evening, especially for the northern Sacramento Valley. Lingering
showers during the day Thursday, with dry and mild conditions for
Friday and Saturday. A wet system is likely on Sunday.
Our next system is a shortwave approaching the coast with a band
of generally light precipitation ahead, currently moving through
the area north of Interstate 80. A strong 140 kt jet with this
system is currently located off the coast, but will split as it
moves inland later this afternoon. Precipitation chances will
increase and spread southward through the day and then peak
tonight as a cold front passes through. Dynamics will be weakened
with the split jet but along with a moist Pacific plume will
still be sufficient to bring a decent period of heavier rain later
tonight, especially to the mountains of Shasta County. Rainfall
totals could locally reach up to 2 inches there, with mountains
and foothills elsewhere north of I80 seeing around .75 to 1.5
inches. The Valley could get around .75 inches over the north end,
down to around .15 inches for the northern San Joaquin.
Instability overnight with the passage of the could front could
bring a few embedded thunderstorms to the northern/central
Sacramento Valley. Snow levels with this warm system should be
high with this mild system, until Thursday morning, when
precipitation is decreasing. An inch or two of snow is possible at
Southerly winds will pick up later this afternoon and peak before
midnight with the frontal passage. The surface pressure gradient
will be tight enough when combined with winds just off the
surface to bring locally windy conditions to the northern
Sacramento Valley. A wind advisory is in effect there from 4 pm to
1 am Thursday, due mainly to travel difficulties from gusty winds
combined with slick roads and poor visibility from moderate rain.
Winds elsewhere will be be breezy but not as strong.
Lingering showers continue through the day Thursday. By evening
these should mainly be over the northern mountains. Higher
mountains could see some light snow accumulations.
Upper level ridging will bring dry and mild conditions for Friday
and Saturday. Valley highs in the low to mid 70s are expected. EK
.Extended Discussion (Sunday through Wednesday)
Extended models in fair agreement in bringing Pacific frontal
system into Northern California Sunday afternoon. Tropical
moisture feed into this system topping 1 and a third inches so
this system should be a fairly good precip producer. Snow levels
with this warm system will be quite high and generally above 7000
feet so impacts will be minimal. Due to warm airmass...daytime
highs are expected to come in around normal despite cloud cover
and precipitation. Current model timing of front moves it into the
Sierra by early Monday with rain and snow transitioning to showers
during the day on Monday. Some breaks in the cloud cover Monday
should allow some valley locations to warm a bit. Upper ridging
pushes in from the West by Tuesday morning bringing an end to the
shower threat. Surface high pressure nosing into the Pacific
northwest will bring breezy north winds to the forecast area on
Tuesday. Clearer skies and warmer airmass with bring up daytime
highs to a few degrees above normal.
Weak Pacific frontal system moving though NORCAL this morning with
stronger system passing through this evening and tonight. Generally
VFR local MVFR over the valley today and MVFR/IFR over mountains
in -RA/BR. AFter 03z Thursday becoming MVFR/IFR over the valley in
rain and IFR/LIFR over mountains in -RA/BR. Increasing southerly
flow today with gusts to 40 knots between about 00z and 06z this
evening over higher terrain.
wind advisory from 4 pm this afternoon to 1 am pst thursday
northern sacramento valley.