Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Sacramento California
850 am PST sun Jan 22 2017
showers and isolated thunderstorms with mountain snow continue
today and Monday. Drier weather Tuesday into the weekend except
for a slight chance of some light mountain showers midweek.
frontal system pushing through southern portions of the forecast
area this morning. Satellite imagery showing clearing behind the
front. Wind speeds remained at higher end Wind Advisory criteria
throughout the area overnight as expected, with ksck the
exception at 40 mph sustained for one observation. Wind speed has
decreased with fropa and advisory expires at 10 am. Wind will
remain somewhat breezy today, weakening by evening. Post frontal
showers expected as vertically stacked system remains quasistationary
off the Oregon coast. Models showing significant amount of cape
developing over the Central Valley this afternoon while BUFKIT
profiles reveal strong 0-1km and 0-6km shear profiles. With
clearing, daytime heating, and mid level cooling, instability
increases today, especially in the afternoon. Thus likely to see
some thunderstorms develop later today in the Central Valley.
With 500 mb temps near -30 deg c potential for small hail exists
with stronger storms. Also, given amount of shear, can't rule out
funnel clouds or brief touchdowns.
In the northern and coastal mountains, snow showers have
diminished and will likely cancel the Winter Storm Warning for
those areas this morning. Additional showers possible today and
tonight, but any additional accumulations will be light. Snow
levels forecast around 2500 to 3500 feet for those areas.
More widespread snow showers continue over the mountains of
western Plumas and west slopes of the northern Sierra Nevada today
into tonight where Winter Storm Warning remains in effect. Snow
levels 3500 to 4500 feet today...lowering into the upper foothills
tonight into Monday morning. Accumulations of a few inches
possible in the upper portions of the NE foothills and motherlode
Quasistationary stacked system progged to dig slowly off the West
Coast Monday as it fills. Continued threat of showers and isolated
thunderstorms Monday. Snow showers continue a possibility in the
mountains but with lighter accumulations.
Drier northerly flow sets up on Tuesday as upper ridging
approaches the West Coast and subsidence increases over interior
Extended discussion (thursday through sunday)
Models consistent for next Thursday in placing an upper level
ridge over the eastern Pacific while dropping a week trough
southward into the Great Basin. Can not rule out a slight threat
of light showers over the northern mountains and southern Cascades
on Thursday but any precipitation amount will be quite light and
remain over the mountains. By Friday...upper ridge recenters over
the West Coast bringing dry conditions entire County Warning Area with daytime
highs several degrees above normal. Upper ridging remains over the
west through the rest of the weekend for continued dry conditions
and above normal temperatures. Light northerly winds through the
period will likely keep valley fog limited mainly to south of
Sacramento. Otherwise fair skies overnight will allow overnight
lows to drop to a little below average.
impvg conds with fropa. For cntrl Vly, nrn and cstl mtns, mnly VFR
conds exc LCL MVFR/IFR poss in showers. Isold tsra/tsrags poss
btwn 20z and 02z tda. For wrn Plumas and siernev mtns, wdsprd
MVFR/IFR conds with LCL LIFR in shwrs nxt 24 hrs. Sn lvls 035-045
ft amsl tda lwrg to arnd 025 ft amsl tngt.
Winter Storm Warning until 4 am PST Monday for West Slope
northern Sierra Nevada-western Plumas County/Lassen park.
Wind Advisory until 10 am PST this morning 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.
Winter Storm Warning until 4 PM PST this afternoon for mountains
southwestern Shasta County to Northern Lake County-Shasta Lake