000
FXUS66 KSTO 252125
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
225 PM PDT Thu Apr 25 2024



.Synopsis...
Light rain and mountain snow this afternoon through Friday with
thunderstorm chances today and tomorrow. Highest precipitation
amounts and thunderstorm probabilities will be over the foothills
and mountains. Dry weather and a warming trend returns over the
weekend and into next week.

&&

.Discussion...
Pesky and patchy low stratus continues to hang out over the
central Sacramento Valley as seen on GOES-West visible imagery
this afternoon as scattered showers begin to trickle over the
Coastal Range and into the northern Sacramento Valley. Shower
coverage and cloud cover are expected to increase as a weak
weather system moves through the area today and tomorrow.

Thunderstorms will be the main threat as we close out the work
week with a 15 to 20% chance of isolated thunderstorms over the
mountains/foothills this afternoon/evening. Thunderstorm chances
and coverage increases on Friday with a 15 to 30% chance over the
eastern Valley in addition to the Sierra foothills/mountains.
High resolution models depict storms developing by mid-morning and
persisting through the evening hours.

Overall precipitation amounts will be minimal and low impact, with
the bulk of the moisture staying over the mountains and foothills.
The National Blend of Models depicts under a 0.25" of rainfall
over most of the Valley, the exception being the northern
Sacramento Valley where the NBM has roughly a 20% chance of 0.25"
or more. The highest probabilities are over the
foothills/mountains where the NBM has a 20 to 40% chance of 0.50"
or more of rain. Due to the warm nature of this system, snow
levels will be around 7000 feet through this evening before
lowering to 6000-6500 feet on Friday. Highest snow totals will be
along the highest peaks south of HWY 50 where the NBM has a
40-60% chance of 2.00" or more of snow. Winds will be breezy out
of the west-southwest with strongest gusts of 25 to 30 mph through
the Delta and over the mountains today and tomorrow, gusts will
be 15 to 25 mph through the Valley.

By the weekend, dry weather returns as heights begin to increase
and weak ridging moves in. Temperatures will gradually start to
increase with Valley highs in the 70s and 80s. Over the
foothills/mountains, high temperatures will be in the 60s and 50s,
respectively. Winds will be light and breezy out of the north as
this weather system exits the region.

//Forrest


&&


.EXTENDED DISCUSSION (Monday THROUGH Thursday)...
As we start off the work week, zonal flow and dry weather
continues with Valley highs in the 70s & 80s and 50s & 60s over
the foothills/mountains. Cluster analysis and ensemble guidance
depict zonal, onshore flow over NorCal as a high pressure ridge
hangs out over the Pacific and a low tracks eastward just north of
the Pacific Northwest. This pattern continues along with a
warming trend and above normal temperatures through Wednesday
before variability in the clusters appears in regards to a trough
potentially digging down over NorCal by late week. Uncertainty
remains in the forecast, so be sure to check back frequently for
updates!

//Forrest


&&


.AVIATION...
VFR conditions expected over the next 24 hours with isolated
areas of MVFR/IFR due to showers/thunderstorms (15 to 20%) over
the foothills/mountains (thru 12Z Fri) as a weak weather system
moves through the area today. West-southwest surface winds gusting
25 to 30 mph through the Delta and over the mountains (20Z Thurs
to 14Z Fri) with Valley gusts 15 to 25 mph (thru 07Z Fri). Snow
levels will be between 6000-7000 feet. Tomorrow, there is a 15 to
30% chance of isolated thunderstorms in the Valley & Sierra
foothills/mountains from 18Z Fri to 05Z Sat.

//Forrest


&&

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

$$