000
FXUS66 KSTO 040920
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
220 AM PDT Sun Jun 4 2023

.SYNOPSIS...
Shower/thunderstorm chances over the mountains today, then become
more extensive beginning Monday. Temperatures will be above
average today, then cooler weather returns.

&&

.DISCUSSION...
Skies are mostly clear across interior NorCal early this morning.
Debris cloudiness from Saturday`s convection in the Sierra is
moving north along the Nevada border. High pressure over the
region is resulting in milder temperatures, and is suppressing
marine influence inland. Current temperatures are milder than 24
hours ago and generally range from the 50s to mid 60s in the
mountains, to the 60s to mid 70s across the Central Valley.

Hot weather will continue today with most areas likely to see the
warmest temperatures of the week, and some areas of the northern
Sacramento Valley may reach the century mark. Widespread moderate
heat risk will cover the valley and lower foothills. Isolated to
scattered late-day thunderstorms will spread further north up the
Sierra and Cascade Range today.

Moisture will continue to flow into NorCal from the south and east
through mid-week as a low develops near the central California
coast. This will lead to an increasing threat of mainly late day
showers and thunderstorms over the mountains as TPW and elevated
instability increase, and some of these storms may migrate down
into the valley in the evenings. Heavy rain will be possible with
thunderstorms, and increasing bulk shear of 20-30 kts on Monday
and Tuesday may lead to a non-zero threat for large hail with
stronger storms.

The combination of increased cloud cover, synoptic cooling from
weakening high pressure, and increased onshore flow will result
in a cooling trend for the entire area by Tuesday with high
temperatures returning to below normal.

Area waterways continue to run cold and fast as a consequence of
the melting Sierra snowpack. Be sure to exercise cold water safety
if you`re near area waterways this weekend.

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...
Closed upper low weakens to trough Thursday as it moves into the
Great Basin. Another short wave trough looks to follow it Friday
into the weekend. Threat of afternoon and evening showers and
thunderstorms will continue over the mountains and possibly into
the northern and central Sacramento Valley. NBM forecasts near to
slightly below normal high temperatures Thursday into Saturday,
warming to slightly above normal Sunday.

&&

.AVIATION...
VFR conditions over interior NorCal next 24 hrs except isolated
MVFR/IFR possible over mtns in shra and tsra. Sfc wind mainly
below 12kts except vcnty of Delta SWly wind up to 20 kts.

&&

.STO WATCHES/WARNINGS/ADVISORIES...None.

&&

$$