Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 021604
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
804 AM PST Sun Mar 2 2014
Moist westerly flow will continue over NorCal the next several
days. Multiple weak weather systems will move across the area with
mainly light precipitation. A more significant weather system will
possibly affect the region later Wednesday into Thursday.
WSWly flow continues to bring moderately deep moisture with TPW
approaching an inch into NorCal. Another system moves across the
area today with enough warm advection to generate weak lift
sufficient for areas of light precip, mainly over the mountains.
Will update forecast to indicate higher pop but low QPF.
Next system approaches later Monday and Monday night and will
likely be another high pop/low QPF event with only minor impacts
expected. Stronger system lurks for later in the week - Wednesday
night into Thursday with potentially heavier QPF.
Updates out shortly.
Relatively flat high pressure is forecast to remain over the state
for the next several days. Weak Pacific disturbances will bring a
threat of precipitation to much of the CWA each day through
Wednesday. A weak shortwave trough now riding over the west coast
ridge is currently bringing variable cloudiness to the CWA as well
as a few light showers north of about Chico. Another shortwave
trough and surface front now at about 130 west is starting break
apart as it hits the west coast ridge. Although dynamics with this
system will be quite weak as it moves across NORCAL...Blended TPW
product shows a fairly good moisture tap of 1.2 inches feeding it.
Therefore...Expect measurable precipitation is likely across the
northern most areas tapering to a slight threat south of
Sacramento. With lack of dynamics under the ridge...heavy
precipitation is not expected anywhere and with above 6000 foot
snow levels in warm airmass mountain travel impacts should be
minimal as well. Another batch of Pacific moisture is forecast to
push into NORCAL late Monday. Light overrunning precip is likely
over the northern part of the state on Monday with increasing
threat of precipitation spreading southward by evening. Again...
precipitation amounts are likely to be relatively light except for
the western Shasta county mountains where orographics and better
lift could bring a moderate amount of precipitation. A brief
amplification of the west coast ridge on Tuesday will bring a
reduced threat of precipitation most areas and a warm up of
several degrees in daytime temperatures. Mid range models in good
agreement in bringing a stronger Pacific frontal system into the
coast around Wednesday of this week...temporarily knocking down
the ridge and bringing a good chance of precipitation to most of
the forecast area.
.Extended Discussion (Thursday through Sunday)...
Models continue to show a weak mid-week storm arriving Wed-Thurs.
The models are in good agreement that the main moisture band will
move through between 10 pm Wednesday through 4 am Thursday. The
available moisture moving across the region will range from
0.8-1.3" of PW according to GFS. Have kept a chance of rain in the
valley for Thursday morning/afternoon then reduced to a slight
chance of precipitation Thursday night mainly in the northern Sac
valley and surrounding terrain. Snow levels during this system
will generally be above pass levels.
High pressure ridging develops by Friday and strengthens over the
weekend...bringing dry and warmer weather with daytime highs
running up to 10 degrees above normal. Valley highs will
experience widespread low 70s Friday into Sunday. Models indicate
the next brush of moisture could arrive Sunday afternoon into
Generally VFR conditions. Isold to sctd showers moving across
NorCal will bring a mix of MVFR/VFR with some low to mid clouds
over the area. A mix of VFR/MVFR conditions over the mountains
with local IFR conditions during isolated showers. Snow levels
around 5500 feet. South winds 5 to 15 mph in the valley today.
Light to moderate west to south flow aloft. JBB