000
FXUS66 KSTO 242032
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
132 PM PDT Wed Apr 24 2024

.Synopsis...
Cool and unsettled weather this week. A chance for afternoon
showers and thunderstorms over the mountains today. Precipitation
chances increase Thursday afternoon and Friday as a weather
system moves through, best chances in the foothills and mountains.

&&

.Discussion...
Afternoon GOES satellite imagery shows partly to mostly cloudy
skies across interior NorCal. Near to slightly below average
temperatures are forecast this afternoon. NorCal remains in
between systems as upstream short-wave energy approaches from the
Gulf of Alaska and the closed low moves into SoCal later today.
Another round of isolated showers or thunderstorms will be
possible today, mainly over the northern mountains and the
northern Sierra south of Highway 50. The NBM indicates a 10-20%
chance of isolated thunderstorms this afternoon.

Ensembles show the next wave sliding southward later Thursday into
Friday, bringing the potential for light showers. Best shower
chances will be over the foothills and mountains. Little to no
impacts are expected with this system. WPC guidance indicates
less than 0.10" in the Valley, and generally around 0.10-0.50"
over the foothills and mountains. A few inches of snowfall
accumulation will be possible over the higher elevations (snow
levels above 6-7k ft) in the Sierra, but travel impacts will
likely be minimal. The NBM projects a 15-30% probability of
thunderstorm development Friday afternoon and evening. Lightning,
brief heavy rain, gusty winds, and small hail will be possible
with any thunderstorms that develop.

Dry conditions return Saturday as riding from the eastern Pacific
builds into the region. Forecast highs will be in the low to 70s
across the Valley, 60s to low 70s over the foothills, and upper
40s to low 60s over the mountains.

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...
Dry weather Sunday as weak short wave ridging moves through
interior NorCal. Cluster analysis is in decent agreement on
general weak ridging/zonal flow remaining across NorCal into next
week. By mid next week, ensembles diverge and variation of
solutions spreads, so confidence beyond Monday is somewhat low.
Potential scenarios being displayed in the clusters includes
continued zonal flow with ridging centered across the southwest
and troughing to our north across the PacNW, and then variability
on how deep the northern trough could dig and associated timing
difference with it. Stay tuned as details become more clear for
the forecast next week.

//Peters

&&

.AVIATION...
VFR conditions over next 24 hrs except for MVFR/IFR conditions in
isolated showers or thunderstorms over the mountains through
03z-06z Thursday. A weather system will bring showers to interior
NorCal Thursday afternoon-Friday, with areas of MVFR/IFR
conditions after 18z Thursday. Surface wind mainly below 12 kts
except vicinity of Delta with southwesterly winds up to 18 kts
after 00z Thursday. Increasing southwesterly winds after 18z
Thursday, mainly over the mountains and vicinity of Delta.

&&

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

$$