263
FXUS66 KSTO 282034
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1234 PM PST Tue Jan 28 2025
.SYNOPSIS...
Dry weather and cold morning lows continue through Thursday.
Unsettled weather returns Friday and continues into next week
with periods of light to moderate rain, high elevation mountain
snow showers, and breezy southerly winds.
&&
.DISCUSSION...
Current GOES-West visible satellite imagery illustrates sunny
skies across interior northern California on this Tuesday
afternoon. Near to below freezing low temperatures from this
morning have since increased to the 50s in the Valley and 40s to
50s in the foothills and mountains, valid at 1230 PM PST. Overall
light winds and tranquil weather conditions are being observed.
The upper level pattern will feature ridging over the Pacific
Northwest and a closed low to our south, with an eastward
progression over the next few days. This will allow for dry
weather and cold morning low temperatures to prevail through
Thursday. The National Blend of Models (NBM) shows a 65 to 95
percent probability of morning low temperatures less than 35
degrees over the next two days, allowing for frost development
across much of Valley and into the foothills. Be sure to monitor
the latest forecast and take the necessary precautions to protect
pets, plants and people!
A pattern change to unsettled weather will return late-week and
bring precipitation back to the forecast beginning Friday.
Precipitation initially starts early Friday morning for the far
northwestern parts of our area, then spreads east and south into
the Valley and over the Sierra through the afternoon and evening.
Snow levels will begin at around 4000-6000 feet Friday morning,
then rise to around 6000-7000+ feet Friday evening, allowing for
minor accumulations at the higher elevations of the mountains on
Friday. Unsettled weather then continues through the extended
forecast period.
&&
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Cluster analysis and ensemble guidance have come into slightly
better agreement for part of the extended forecast period.
Ensembles continue to show upper level troughing influencing
NorCal this weekend bringing continued unsettled weather into next
week. The NBM shows a 60 to 90 percent probability of rainfall of
1 inch or greater over 72 hours from Saturday through Tuesday
north of Interstate 80, and a 25 to 55 percent probability south
of Interstate 80. The NBM also suggests a 30 to 50 percent
probability of snow amounts of 4 inches or greater over the same
timeframe. Snow levels currently are trending around 7000-8000
feet or higher over the weekend, potentially lowering slightly to
around 6000-7000 feet early next week.
There is still some uncertainty though with regards to exact
details such as precipitation amounts, timing, and snow levels
especially for early to mid next week. However, Integrated Vapor
Transport (IVT) continues to show decent agreement between the EC
and GEFS, showcasing roughly a 50-70% chance of moisture being
present through at least Tuesday of next week. Periods of breezy
southerly winds will also return to interior NorCal over the
extended forecast period. Be sure to check back for more details
as we get closer, and stay up to date with the latest forecast at
weather.gov/sto!
&&
.AVIATION...
VFR conditions are expected across interior NorCal next 24 hours.
Surface winds generally less than 12 knots, except for
northeasterly wind gusts up to 20-25 knots across the northeastern
foothills/mountains from around 03z to 18z Wednesday.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
