000
FXUS66 KSTO 262008
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
108 PM PDT Fri Apr 26 2024

.Synopsis...
Mountain snow continues through the evening with thunderstorm
chances today, highest over the foothills and mountains. Mild and
warmer weather in store this weekend into early next week.

&&

.Discussion...
Showers are ongoing over the foothills and Sierra and expected to
continue through the afternoon. Ski resorts reported 1-4 inches of
snowfall from yesterday above ~6800 feet, which was also
supported via snow level radars and when looking at CCTV cameras
along I-80 & Highway 50 this morning. An area of light
precipitation allowed for 1-2 hours of light snowfall down to
around 5,000 feet late morning today in the Blue Canyon area as
temperatures were around 33-35 degrees. Temperatures have
increased for elevations between 5000-6000 feet this afternoon,
likely limiting snowfall potential again with additional shower
activity in the mountains through this afternoon-evening.
Additional snowfall of 1-4 inches is possible today for higher
elevations and mountain peaks, again mainly above 6000 feet.
Breezy winds associated with these showers this morning/early
afternoon have been between 15-30 mph. Similar winds will continue
to be possible with any shower/thunderstorm development through
this evening. Impacts will continue to be minimal through today
but be sure to be cautious if planning mountainous travel as roads
may be slick.

Cumulus clouds have begun to develop/fill in across portions of
the Valley early this afternoon, and even some isolated low-top
showers have begun to pop-up. Latest hi-res forecast model runs
shows continued scattered showers and isolated thunderstorms north
of I-80 over the mountains and foothills through the afternoon. A
few more isolated showers and thunderstorms from Yolo County to
Stanislaus County this afternoon through the evening (~7pm PDT),
where mesoanalysis is already indicating CAPE of around 250-500
J/kg has developed. Hires indicates unidirectional shear around
20-30 knots, with storm motions of 25-30 kts from the northwest
and mean echo tops of generally 5-15 Kft, a few getting up to
around 20 Kft. All of this to say, any thunderstorms that do
develop should move quickly southeast and bring brief moderate to
heavy rain, lightning, and winds to around 20-30 mph. Strongest
storms may have small hail.

Shower and thunderstorms will diminish by 7-8pm this evening,
leaving behind mostly dry conditions. Dry weather is expected
through the weekend and into at least early next week as weak northerly
flow overhead will transition to become more zonal. As a result,
occasionally breezy (up to 15-25 mph) northerly winds are in the
forecast, strongest in the north wind- prone areas through early
next week as short waves move through WA/OR to our north.
//Peters
&&


.EXTENDED DISCUSSION (Tuesday THROUGH Friday)...

Northwesterly flow over NorCal on Tuesday and Wednesday as short
wave troughs remain north of our area, and ridging develops in the
Pacific. High temperatures will climb into the low 80s for much
of the Valley on Tuesday and Wednesday. Thursday and Friday, there
is disagreement amongst the ensembles on what our upper level
pattern looks like. Cluster analysis suggests around a 50/50 split
among members of ridging developing over the area and a trough
developing in the eastern Pacific. The NBM appears to be favoring
the resolution suggesting weak troughing over the PacNW and brings
a low chance (10-20%) of showers, mainly over the Shasta
mountains, Thursday and Friday. High temperatures will be
determined by which pattern manifests over the area, as there is
currently a large spread on potential high temps Thursday and
Friday by 10-13 degrees. Current forecast highs however remain
close to climatological normal for this time of year, in the upper
70s to low 80s for the Valley and upper 50s to upper 60s for
higher elevations. &&

.AVIATION...

Areas of MVFR/IFR conditions due to periods of showers, mountain
snow showers, and isolated thunderstorms across portions of
interior NorCal until around 03Z Saturday. Snow levels 5500-6500
feet. Otherwise, mainly VFR conditions are expected next 24
hours. Surface wind mainly at or below 12 kts except breezy
southwest to west wind gusts up to 20-25 kts possible vicinity of
Delta and N San Joaquin Valley, and northwest wind gusts vicinity
N Sacramento Valley through 06z Saturday. Areas west to northwest
surface wind gusts up to 30 kts possible over the mountains through
00Z Saturday.

&&

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

$$