Area forecast discussion
National Weather Service Sacramento California
913 PM PDT Monday may 20 2013
Short term discussion...
Low pressure area off the Washington and Oregon coast will deepen
on Tuesday bringing cooler air to the interior and stronger flow
through the Delta. Strong gradient from sfo-SAC will set up during
the day peaking at around 5 mb. Winds might start to pick up
through the Delta in the morning hours. Not much in the way of
stratus is expected by morning and during the day so the flow is
most likely being driven by the low pressure area to the north.
In California the low looks fairly moisture starved but there
might be just enough moisture to touch off a few showers over
extreme northern California on Tuesday.
As the low dips further south on Wednesday and Thursday there will
be a slightly better chance for some showers to develop over the
northern mountains. Temperatures will likely remain in the 70s
in the Central Valley both days tapering to the 50s for the
mountains. The surface flow will shift to a northerly direction on
Wednesday behind a short wave rotating around the base of the low
and might become a little breezy during the day.
Extended discussion (friday through monday)
Strong closed low will lift to the northeast Friday and away from
norcal. The European model (ecmwf) is a bit quicker...while the GFS is slower and
allows some showers to linger in far northern California Friday.
By Saturday...another shortwave develops on the backside of the
closed low and swings toward the West Coast. Models show some
instability developing Sat afternoon around the coastal
mountains...and have thus added a light chance of thunder in that
area. Models are in good agreement with pushing the trough axis
over our area Sunday...bringing a chance of showers to the higher
elevations with continued cool temperatures for the the entire
forecast area.
Model uncertainty increases for the Memorial Day Holiday...but
the overall consensus is weaker troughing along the West Coast
allowing temperatures to return to around normal with a continued slight
chance of showers in the mountains. -Dvc
&&
Aviation...
VFR conditions continue next 24 hours for interior norcal. Onshore
flow increases Tuesday in the afternoon (strengthening southerly
winds SAC valley...northerly in San Joaquin valley) as a low
pressure system approaches norcal.
&&
Sto watches/warnings/advisories...
none.
&&
$$
