NATIONAL WEATHER SERVICE FORECAST DISCUSSION
Area Forecast Discussion
Issued by The National Weather Service
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000
FXUS66 KSTO 150612
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1010 PM PST Thu Feb 14 2019

.SYNOPSIS...
Strong storm event continues to bring widespread precipitation to
the region. Heavy snow will continue in the mountains as snow
levels lower overnight. Local flooding with ponding on roads and
rises on streams and rivers possible through tomorrow. Periods of
wet weather continue into the weekend.

&&

.DISCUSSION...
Evening Update: After a brief break/lull in the precip, the next
round began to move across the CWA this evening. At press time, the
leading edge was nearing SAC with more precip heading into the 80/50
corridor. Snow level radar at Shasta Dam shows the snow level around
3 kft and this is likely near the level the snow level will be in
the Sierra plus 500 ft or so later this evening.

An impressive cellular form mass of clouds is associated with the
offshore upper low center as it impacts Norcal on Fri indicating a
cold, unstable, showery air mass will be affecting the area.
Subsequent short waves will move through the upper trof on Sat ahead
of a reinforcing shot of cold air from another GOA low center
dropping Swd into our area on Sun. Snow levels will steadily lower
over the weekend, even near or below 1 kft in the Shasta Co mtns,
Sat nite and Sun, possibly affecting the RDD area again, and into
the foothills as low as 2 kft or so. However, the QPF will be much
lighter so snow amounts will also. That being stated, it still looks
as if the Sierra will receive another yard or two of powder this
weekend due to the cold air and high snow ratios.

For hydro concerns: Since the areal flood warning and river flood
warnings are in effect over a large portion of the CWA, we let the
areal flood watch expire as it had served its purpose in preparation
but now we are in the action/reaction phase.    JHM

.Previous Discussion...
Wet winter storm continues to bring multiple impacts to NorCal
through Friday. Thunderstorms formed along the cold front this
morning as it passed through NorCal, bringing heavy rain to the
Valley. Flash flooding occurred over portions of El Dorado,
Calaveras, Amador, and Tuolumne Counties late this morning as
thunderstorms stalled over those areas. Heavy rain has since moved
out of the area as the front has moved east, though lighter
precipitation is lingering behind the front.

The next round of heavier precipitation is expected to begin
overnight. Heavy snow is currently falling over the Northern
Sierra and is expected to increase overnight. Snow levels have
fallen to around 4000 to 5000 feet behind the frontal passage and
are expected to fall further to 2000 to 3000 feet overnight. An
additional 3 to 5 feet of snowfall are forecast through Friday
night at pass level with locally higher amounts possible. As the
snow levels drop, an additional 8 to 12 inches of snow is also
forecast over Interstate 5 north of Redding. For liquid
precipitation, another half an inch to an inch is expected in the
Valley, and 1 to 3 inches is possible in the foothills.

Strong southerly winds have been observed today with gusts up to
45 to 50 mph recorded in the Vally and up to 65 mph over the
mountain peaks. Winds expected to pick up again overnight with
this next wave of the storm, and the wind advisory is still in
effect through 6am Friday.

River flooding and localized road and small stream flooding is
still occurring across NorCal in the wake of the heavy rain that
has fallen the past few days. Rain over the snow that fell at low
elevations the past few weeks has caused much of the snow to melt
and runoff. Many river locations are forecast near or above
monitor or flood stage.

Interesting temperature scenario occurred today for many NorCal
locations. Today`s high temperatures actually occurred in the
early morning hours after the warm front moved passed through the
area. Temperatures dropped 5 to 10 degrees as the cold front moved
through mid-morning.

Wet and cooler pattern will continue into the weekend as several
disturbances drop down from the northwest bringing showers and
adding to the snowpack in the mountains. HEC

.EXTENDED DISCUSSION (Monday THROUGH Thursday)

Unsettled weather continues through the weekend with scattered
rain showers in the Central Valley and snow showers in the
foothills and mountains. Drier weather, along with some breezy
north to east wind, expected Monday into Tuesday as subsidence
increases over Interior NorCal. Models diverge enough by the
middle of next week to lead to forecast uncertainties. Daytime
temperatures remain below normal through the extended forecast
period.


&&

.AVIATION...

Areas MVFR with lcl IFR/LIFR conds ovr Intr NorCal nxt 24 hrs in
shwrs and poss isold tstms. Sly sfc wnd gsts up to 45 kts poss in
Cntrl Vly til abt 12z Fri and to 55 kts or gtr ovr hyr mtn trrn
til arnd 20z Fri. Sn lvls lwrg to 025-035 ft by Fri mrng.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 8 PM PST this evening for Carquinez Strait and
Delta-Central Sacramento Valley-Clear Lake/Southern Lake County-
Motherlode-Mountains Southwestern Shasta County to Northern Lake
County-Northeast Foothills/Sacramento Valley-Northern Sacramento
Valley-Northern San Joaquin Valley-Shasta Lake Area / Northern
Shasta County-Southern Sacramento Valley-West Slope Northern
Sierra Nevada-Western Plumas County/Lassen Park.

Winter Storm Warning until 4 AM PST Saturday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Wind Advisory until 6 AM PST Friday for Clear Lake/Southern Lake
County-Mountains Southwestern Shasta County to Northern Lake
County.

Wind Advisory until 6 AM PST Friday for Carquinez Strait and
Delta-Central Sacramento Valley-Motherlode-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley.

Winter Storm Warning from midnight tonight to 4 AM PST Saturday
for Burney Basin / Eastern Shasta County-Shasta Lake Area /
Northern Shasta County.

&&

$$
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