NATIONAL WEATHER SERVICE FORECAST DISCUSSION
Area Forecast Discussion
Issued by The National Weather Service
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650
FXUS66 KSTO 141208
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
408 AM PST Thu Feb 14 2019

.SYNOPSIS...
Strong storm event continues to bring widespread precipitation to
the region. Snow levels will lower again this afternoon with heavy
snow returning to the mountains. Local flooding with ponding on
roads and rises on streams and rivers possible today. Periods of
wet weather continue into the weekend.

&&

.DISCUSSION...
Warm front presently over the central Sacramento Valley continues
to move only very slowly to the north. There`s a big temperature
gradient across the front with lower to mid 60s in the Sacramento
area and lower 40s in the Chico area. Strong southerly winds have
been going all night south of the front where winds have been
gusting to 35-45 mph.

Moderate to heavy precipitation has been focused overnight along
the front to the north of Sacramento with more scattered rain to
the south. Rainfall amounts since Wednesday evening have been
around 1/2 an inch to an inch in the Sacramento Valley north of
Sacramento with 1 to 3 inches across the surrounding foothills and
mountains.

987 mb surface low presently just off the northwest coast of
California forecast to move up into western Oregon this morning
(taking the warm front with it up into far northern California)
while the cold front moves ashore. The gusty southerly winds are
then forecast to work their way up the Sacramento Valley as
surface gradients tighten and better mixing develops behind the
cold front. Strong southerly winds will continue in the valley and
foothills into early Friday with gusts of 45-55 mph.

Cold front pushes inland this morning and is forecast to reach the
northern Sierra around midday. Widespread precipitation is
forecast to taper in the valley behind the front this morning, but
will continue across the northern Sierra. Snow levels are forecast
to drop to around the pass levels around noon, and to below 5000
feet by mid-afternoon.

It looks like another heavy snow event shaping up for the northern
Sierra west slopes into Saturday with lowering snow levels, and
steeper lapse rates with more favorable upslope flow supporting
heavier snowfall rates. Current forecast is for around 4-5 feet of
snow accumulation at KBLU through early Saturday.

Potential for thunderstorms from late morning into the afternoon
in the increasingly unstable environment post-front. Small hail
and strong winds are the primary threat. However, surface
troughing forecast in the lee of the Coast Range may allow enough
backing of low-level flow in the Sacramento Valley to allow for
persistent convection to develop rotating updrafts with potential
for a few funnel clouds or perhaps a weak tornado.

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.

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)
Main upper trough will be located over the southwest US leaving
NorCal dry by early Monday. A moderate pressure gradient across
the Sierra Monday and Monday night will bring breezy north winds
to the area with high temperatures continuing to be below normal.
Upper ridging Tuesday will keep one more day of dry weather before
models depict the potential for another system Wednesday. Small
chances for precipitation continue from Wednesday on, but models
are still quite a bit different leading to low confidence with any
precipitation chances for mid-week.

&&

.AVIATION...
VFR/MVFR conditions expected for the next 24 hours. Gusty south
to southwest winds expected through the period with gusts up to 40
knots possible. Best chances for thunderstorms between 18-22Z at
sites. Rain may become more scattered this afternoon.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through 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 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-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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