000
FXUS66 KSTO 202026
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
126 PM PDT Sat Apr 20 2024

.Synopsis...
Warm and dry weather continues into early next week. Locally
breezy winds at times through the Delta. Cooler, near-normal
temperatures return Tuesday through the end of the week with
onshore flow. Precipitation chances return Wednesday through
Saturday.

&&

.Discussion...
Upper level ridging continues to dominate the synoptic pattern
through Monday. Warm and relatively quiet weather will prevail
across interior NorCal, with high temperatures in the low to mid
80`s for Valley locations. Still an outside shot of reaching 90
for locations from Arbuckle to Orland, and in Redding as the
National Blend of Models projects a 10-40% chance to reach the 90
degree mark. A trough begins to approach the coast late Monday and
alter the upper level flow into a southwesterly component, which
will setup the Delta breeze Monday evening. Southwesterly wind
gusts up to 30 mph will be possible through the Delta.

Trough will continue to move closer to the shore on Tuesday and
will promote more onshore flow to the region, which will cool
temperatures back down into the low to mid 70s for most of the
Valley, with upper 70s still possible in the northern San
Joaquin and northern Sacramento Valleys. An isolated shower or
thunderstorm is possible over the mountains and in northern Shasta
County Tuesday afternoon and evening, although chances remain at
around 10-15%. Breezy southwesterly winds remain in the forecast
for the Delta, with 15 to 25 mph gusts possible Tuesday.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...

On Wednesday, the trough will continue to move inland in SoCal,
bringing slight precipitation chances, mainly to the foothills and
mountains in Tuolumne and Alpine counties. Any precipitation that
does fall will be light and totals appear to be under 0.10"
inches at this time. As the trough moves through SoCal, another
short wave is projected to deepen over the West Coast on Thursday
and Friday. Precipitation chances will be the highest over the
Northeast foothills southward to around HWY-50, then spread across
the Sierra and adjacent foothills on Friday. Then NBM is
advertising a potential for thunderstorms to develop as well on
Friday in the Foothills and Sierra, with around a 10-20% chance of
t-storm development. Rainfall totals have come up slightly since
the morning update, with a general 0.25" to 0.50" in the Foothills
and Sierra. Lighter totals of less than 0.10" inches will be
possible in the Valley. Snowfall does not appear to be impactful
at this time, with a light dusting to an inch along I-80 and
HWY-50, and snow levels are forecast to be at around 6500-7500
feet Thursday night through early Saturday morning. Highest peaks
in the Sierra could receive up to 5 inches of fresh snowfall.
Uncertainty remains high regarding the potential impacts from this
late-week system, so stay tuned to forecast updates.

High temperatures will be near climatological normal during the
extended period. Troughing will support cloud coverage and cooler
air to infiltrate the region, so temperatures should remain in the
low to mid 70s for the Valley, with cooler 40s to low 60s for the
higher elevations from Wednesday through Saturday.

&&

.AVIATION...

VFR conditions over interior NorCal over the next 24 hrs. Surface
wind mainly below 12 kts except vicinity of Delta, with
west southwest sustained wind up to 20 kts.

&&

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

$$