NATIONAL WEATHER SERVICE FORECAST DISCUSSION
Area Forecast Discussion
Issued by The National Weather Service
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000
FXUS66 KSTO 132352
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
352 PM PST Wed Feb 13 2019


.SYNOPSIS...
A strong storm event will bring widespread precipitation with
moderate to heavy rain and mountain snow. Local flooding with
ponding on roads and rises on streams and rivers possible through
Thursday. Periods of wet weather continue into the weekend.

&&

.DISCUSSION...
A strong and very wet system has brought hazardous weather
conditions to the area today. Cold air entrenched across the far
north end of the Sacramento Valley and northern mountains allowed
heavy snowfall to fall into the northern Sacramento Valley since
yesterday evening, with totals up to 10 to 14 inches for Redding
causing major disruption to travel, power outages, and school
closings. Warmer air has spread in, changing precipitation to rain
over the area, including the Sierra passes. Moderate to heavy
precipitation has brought road flooding and stream rises to
portions of the area. An area Flood Warning has been issued as the
concern changes to flooding. This has been extended until
Thursday evening, and expanded northward over the northern
Sacramento Valley, where low snow melt and snow clogged drains
could increase runoff. A Flood Watch continues through Thursday
early evening for much of the area.

The next surface low races northward off the coast up into
western Oregon by midday Thursday. This will also bring another
upswing in precipitation and gusty southerly winds as gradients
tighten to around 15 mbs from SAC to MFR bringing an elevated risk
for power outages and tree damage. A Wind Advisory begins Thursday
morning and continues through early evening. The potential for
flooding issues will increase further as runoff from the ongoing
precipitation is enhanced by low-elevation snow melt.

Snow levels expected to come back down Thursday afternoon and
night as the next cold upper low drops down to off the coast of
Oregon and displaces the milder airmass to the east. At the same
time, snowfall will increase over the northern Sierra Thursday
night as lapse rates steepen and upslope component to the flow
increases. Thunderstorms will be possible in the Central Valley.
Shear and instability are looking increasingly favorable. There is
some potential for debris flows over burn areas due to higher
intensity rainfall over already saturated locations.

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. EK

&&
.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)

Unsettled weather forecast through the weekend as upper low moves
through. More widespread showers expected Saturday becoming
scattered Sunday. Drier weather, along with some breezy north to
east wind, returns Monday into Tuesday as subsidence increases
over Interior NorCal. Models diverge enough by the middle of next
to lead to forecast uncertainties. Daytime temperatures remain
below normal through the extended forecast period.

&&

.AVIATION...

In Cntrl Vly, wdsprd MVFR with areas IFR conds nxt 24 hrs. Lcl SE
sly wnd gsts to 25 kts fm SAC area S. Wdsprd SE sfc wnd gsts to 35
kts aft 07z thru abt 20z Thu. Isold tstm poss. In fthls and mtns,
wdsprd MVFR/IFR with areas LIFR obscrg trrn. Areas S-SE sfc wnd
gsts up to 50 kts or gtr ovr hyr trrn tngt and Thu. Sn lvls
incrsg abv 075 tngt, lwrg to 040-055 Thu aftn.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Thursday 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 Burney Basin /
Eastern Shasta County-Shasta Lake Area / Northern Shasta County-
West Slope Northern Sierra Nevada-Western Plumas County/Lassen
Park.

Wind Advisory from 6 AM to 6 PM PST Thursday 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.

&&

$$
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