Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 280510
Area Forecast Discussion
National Weather Service Sacramento CA
1010 PM PDT FRI MAY 27 2016
A few afternoon showers or thunderstorms over the northern Sierra
through Monday. Very warm weather expected through the middle of
next week. Breezy north winds later today and Saturday.
A few passing high clouds over NorCal this evening under generally
light winds. Current forecast is on track and no evening update
will be needed.
.PREVIOUS DISCUSSION... Northern California remains under
northwest flow aloft between high pressure over the eastern
Pacific and an upper trough over the Pacific Northwest. Skies are
mostly clear across most of the region, and even Sierra cumulus
development is a fair bit less than the past few days. Pressure
gradients have tightened the last several hours, and breezy
northerly winds have developed along the northern and western
Sacramento Valley. Temperatures are now running 2 to 8 degrees
warmer than yesterday, and are expected to peak around 90 degrees
across the Valley.
Heights and thicknesses will increase a bit the next several days
as th eastern Pacific ridge builds eastward. Slight warming is
expected accordingly through the weekend, with peak temperatures
expected on Memorial Day when the Valley could reach the mid to
Isolated showers or thunderstorms will be possible over the higher
Sierra the next several days. A weak upper low will form over
Central and Southern California on Saturday, which could increase
coverage of thunderstorms. Otherwise, forcing and instability will
be relatively limited.
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
The forecast concern during this period continues to be the heat
that will affect northern California with above normal temperatures
through the end of next week. A broad upper level high pressure
system will continue to build into the west from the eastern
Pacific, which will bring widespread temperatures in the mid to
upper 90s across the valley Tuesday. Higher elevations will
likely see the 60s and 70s.
Model forecast solutions start to diverge Wednesday. The ECMWF has
a higher amplitude trough of low pressure moving into the eastern
Pacific, which could bring chances for scattered showers and
thunderstorms to higher elevations in northern California, but
the GFS solution advertises a shortwave trough of low pressure
moving across the Pacific northwest with a ridge of high pressure
still in position over the forecast area. For now, left the
forecast trending towards the GFS solution due to little variation
from previous run compared to the ECMWF with more variability from
the previous forecast period.
In both forecast scenarios, temperatures will cool slightly
towards the end of next week as a trough of low pressure moves
towards northern California, however temperatures will still be
above normal for the forecast area. Chances for precipitation next
week are expected to be minimal.
VFR conditions are expected at the terminals for the next 24
hours. Light wind shifts are expected for TAF locations near
Sacramento overnight. Periodic mid to late morning gusts are
possible Saturday for the terminals, and will last through the