Enough noise in the gutters that we've started looking at weather radar. Perhaps we are turning a corner. Maybe not.
.DISCUSSION...
Key Points:
-First notable precipitation event of the
Water Year will bring
TWO WAVES of widespread measurable
rainfall and mountain snow
accumulations continuing today thru Saturday.
-First Wave (Through this afternoon/evening), Second Wave (Friday
PM-Saturday)
-Following this system, north winds increase through the Valley on
Sunday & Monday
-A
Winter Weather Advisory has been issued for elevations greater
than 6000 feet in the northern Sierra until 5 PM Today. Snow
levels will start around 5000 feet this morning before rising to
around 6000 feet throughout the day
The first wave of our first notable precipitation of the Water
Year has begun across NorCal. Currently seeing light
rainfall
returns on
RADAR across the Valley and Foothills, with some light
snow showers in the Sierra. Total
rainfall accumulations at the
time of this writing range from a
trace to around 0.15", with the
higher totals in the northern Sacramento Valley, specifically at
Redding
AP. This wave of precipitation is expected to continue to
move off to the east-northeast through the morning hours, then a
brief break in precipitation will occur this afternoon/evening,
with some lingering rain showers possible in the northern Sac
Valley. Some lingering upslope mountain snow showers across the
Sierra will also be possible during this "break."
On Friday, another wave of precipitation will rotate around a Gulf
of Alaska low pressure and eject another
trough into the region.
This second wave still has some uncertainty regarding track;
mainly if the second wave takes a more easterly trek we would
likely see less precipitation. The second wave of precipitation
may also bring some
isolated thunderstorms across the Valley and
Foothills, with the NBM showing around a 10% chance for the
aforementioned locations. Any t-storms that do form will have
dangerous
lightning, heavy
rainfall, gusty erratic winds.
Overall
rainfall and snowfall totals have trended slightly down
this morning, although potential impacts remain the same. Snowfall
totals in the Sierra are forecast to be around 6-12" inches
through Saturday, on top of what has already fallen.
Rainfall
totals will range from an additional 0.50" inches to 2.00" inches,
with the lower totals over the Central and Southern Sacramento
and Northern San Joaquin Valleys. Snowfall totals across the
Sierra are still trending at around 4-12" inches, with the higher
totals at the peaks. Snow levels look to fluctuate around
5000-6000 feet when precipitation is forecast.
In terms of products, the
Winter Weather Advisory until 11PM
tonight is still
active, however with the "break" in widespread
precipitation
likely occurring later this morning/afternoon, we
may end the advisory early. With the second wave of
moisture
moving in Friday PM, we are considering another advisory to
capture that event. Stay tuned to our social media accounts and
visit weather.gov/sto for forecast updates.
Finally, on Sunday as the
trough ejects further east, gusty
northerly winds will develop across the area. Northerly wind
gusts of 30 mph will be possible, with the strongest winds along
the I-5 corridor and Delta. Latest NBM probabilities of 30mph
gusts or more for the mentioned areas are around 40-80%. Fire
weather risks should be lowered thanks to the widespread
rainfall
in the forecast, but we will monitor conditions as we move
through the rest of the week.
&&
.EXTENDED DISCUSSION (Monday THROUGH Thursday)...
EPAC upper ridging builds into NorCal next week as upper troughing
digs into the Great
Basin. This pattern will result in dry weather
with gusty north to east next Monday into early Thursday.
Depending on amount of precip this week, locally elevated fire
weather conditions might be a concern later next week. High
temperatures gradually warm through the extended period returning
to near
normal next Thursday.