Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
854 am PDT Tuesday Jun 2 2015
drier and warmer weather returns today as temperatures return to
near average for early June. Local shower and thunderstorm chances
will persist through Wednesday over the northern mountains. Better
chances for showers and thunderstorms will develop by the end of
no significant updates this morning. Current temperatures are
running several degrees warmer in the northern Sacramento Valley
at this hour. For areas influenced by the onshore flow through
the Delta (sac metropolitan region, Stockton, modesto), temperatures are
very similar to this time yesterday. There's still a small patch
of low clouds lingering near the SAC metropolitan region around Mather,
but these will clear out within the next hour or two. Jbb
Previous discussion...skies have mostly cleared out across the
interior of norcal early this morning, though quite a bit of
cloudiness lingers across the northern mountains and Shasta County
in the wake of Monday evening's showers and thunderstorms over the
north state. The Redding Airport was the precipitation Winner for the
evening, recording around half an inch (0.51) while the city only
received a few hundredths of an inch. Several other sites in the
surrounding foothills and mountains had rainfall amounts ranging
from a few tenths up to around four tenths of an inch.
Onshore flow continues into the Central Valley early this morning,
albeit considerably weaker than the past couple of days. Dew
points are higher in the Sacramento region than 24 hours ago and
some stratus is beginning to develop early this morning. This will
likely be gone by mid-morning.
The trough weakens over the region today, and with weaker onshore
flow, temperatures will return to around average for early June.
Little change expected Wednesday.
Daytime heating and weak embedded vorts in the westerly flow may
be enough with lingering moisture to kick off a few late day
showers or thunderstorms over the northern mountains the next
couple of days.
The next strong upstream wave is forecast to approach the West
Coast later Wednesday, then drop southward and close off along
the central California coast on Thursday before moving into socal
on Friday. Models are now in pretty good agreement on the track
and strength of the low which lends confidence to the forecast of
increasing shower and thunderstorm chances later this week,
especially for the foothills and mountains.
Extended discussion (saturday through tuesday)...
the closed low that dropped over central/Southern California is now
expected to slowly drift northward over northern California and western Nevada
and impact the area the threat of convection through Monday. GFS
ensembles showing precipitable water in excess of 1 inch which is
above 90th percentile for this time of year. Interior norcal also
has a 1.5 to 2.5 standardized anomaly, which isn't historic but
something to take notice of for early June. The highest chances of
convection look to be across the mountains, but portions of the
valley look to be in play as the low center remains south and east
of interior norcal. Confidence in this occurring has been
increasing, but the trajectory of this type to cutoff low is
difficult. Temperatures will cool a few degrees over the weekend
and hinge on resulting cloud and precipitation coverage, but will
generally be close to normal. Jclapp
VFR conditions expected for most of the period. Periods of
MVFR ceilings in the southern SAC valley (mainly ksac/kmhr/kmcc) this
morning due to high dewpoints, but should improve by 17z.