704 
FXUS66 KSTO 151400
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
600 AM PST Wed Nov 15 2023


.Synopsis...
Unsettled weather pattern the rest of the week with periods of 
showers and high elevation mountain snow showers. Thunderstorms 
are possible Friday evening through Saturday afternoon, mainly for
areas south of I-80.

&&

.Updated Discussion... 
Current radar as of 550 AM shows some scattered showers moving 
through the Delta and the Sacramento Valley. Rainfall amounts so
far have been light, with a 0.01-0.02 recorded for several
stations in that area. Have updated forecast for the quicker 
onset of shower activity this morning. More widespread showers 
are expected by mid-day, with best chances for later this 
afternoon into the evening. Some patchy fog has been observed this
morning, but high cloud cover should limit widespread fog 
development. The fog is expected to diminish by late morning. EK

.Previous Discussion...
Current radar as of 130 AM shows some isolated showers of the 
coast near the Bay and moving northeast. Our area is clear of any 
showers and will continue to remain that way until the mid morning
when our next wave of showers begins to move in from the south, 
with the Delta and San Joaquin Valley areas having the best 
chances of precipitation before spreading north throughout the 
day. Current National Blend of Models (NBM) has a general 20-80% 
chance of meeting or exceeding 0.25" inches of rain for the area 
today, with the highest probabilities the further south you are. 
Light snow showers will be possible as well in the Sierra and 
Lassen Park, with current snow levels forecasted to be above 
7000-8000 feet, with minor accumulations of 1" inch or less. Worth
mentioning that the 06z HRRR run is showing several waves of 
convective showers moving through near Donner Pass throughout the 
evening, with the HREF probs at around 50% for snowfall rates of 
0.5 inch per hour or more, so we will be monitoring for potential 
higher snow totals as the precipitative bands move through.

For Thursday, much of the same...we will see light showers 
continuing throughout the day again for most of the area, with 
best chances south of I-80. The NBM has a general 10-60% chance of
precipitation for most of the area, with higher probabilities 
south of I-80 and into the Sierra. Probabilities of meeting or 
exceeding 0.25' inches of rainfall are currently 10-40%, with the 
Sierra and higher elevations having a 60% chance. 

For Friday and Saturday, the entire area will see better chances
at showers and possible thunderstorms as the low currently 
positioned off the coast begins to break down and finally move 
onshore Saturday. Areas south of I-80 and in the Sierra again  
stand the best probabilities of exceeding 0.50" inches of 
rainfall, with a 40-70% chance. Areas north of I-80 have a general
10-40% chance of exceeding a half-inch of rainfall. As the low
begins to move to the east late Friday into Saturday, we will see
the chance of thunderstorms increase, mainly for the Delta and San
Joaquin Valley, with a 10-20% chance of thunderstorms. Snow levels
in the Sierra are forecasted to rise to 7500-8500 feet, with a
general 1-4 inches of total snowfall at the highest of elevations.

Wood
&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...Drier weather 
expected Sunday into early next week as EPAC upper ridging builds 
into interior NorCal. Locally gusty north to east wind possible 
late Sunday into early Monday. Ridge flattens some Tuesday into 
Wednesday as Pacific frontal system rides over the top, but 
remains strong over CWA to suggest dry weather continuing through 
midweek. Temperatures trend up Sunday into Monday and forecast to 
remain above normal through the extended period.

&&

.AVIATION...
Generally VFR conditions next 24 hours except for brief periods 
of MVFR/IFR/LIFR conditions in BR/FG and low ceilings this morning
through 17z in the Valley around TAF sites, with local MVFR in 
showers this afternoon into the evening. Surface winds over the 
Valley generally light and variable. Wind gusts below 12 kts 
except 20-30 kts over higher elevations of the northern Sierra 
18Z.

&&

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

$$