Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 210541
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
940 PM PST Thu Nov 20 2014
Weather systems continue to move through NorCal into Saturday
bringing periods of precipitation. The second system is expected
to be the wettest Friday night into Saturday. High pressure builds
over the area next week for generally dry weather and milder
daytime temperatures along with areas of morning valley fog.
Upper trof axis has rapidly moved E of the CWA with the vort max
digging well S of the area as well. Behind the trof axis...
subsidence may be strong to allow for some partial clearing over the
Wrn portion of the CWA...which will only lead to the formation of
dense fog beneath the subsidence inversion. So in the evening update
we tweaked the overnite wording for areas of F+ and OCNL -DZ in the
Central Valley. Lingering light showers may continue for a few more
hours over the W slopes Siernev due to lingering cyclonic flow.
The next system which is more of a plume of moisture embedded in
strong jet stream energy will streak across NorCal late Friday night
and Saturday. This system has the deeper moisture with Pwat values
1.00-1.50 inches. Rainfall amounts will range from .10-.50 for
valleys and 0.75-1.50 inches for the mountains. Snow levels will be
high with this warm system starting around 6500 feet...but rising to
7500 feet through Saturday night. Only an inch or two of snow will
fall at highest elevations.
Ridging and northwest flow will develop on Sunday with drying
conditions. Temperatures will remain near normal.
.Extended Discussion (Monday through Thursday)
Dry conditions expected early next week as upper level ridging
builds over the area. Temperatures are tricky, as lingering
moisture and clearing skies with light wind will allow for fog to
develop at times.
Mid to late next week has become a little more consistent, with the
ECMWF backing off from earlier suggestions of a trough passing
through on Wednesday. This is more in line with the GFS and GEM
models, so have trended drier with forecast. This makes sense as
ridge will probably be slow to break down. EK
Precip winding down over interior Norcal...but any partial clearing
after the upper trof passage moves-by will lead to widespread ST/F+
which will be slow to lift Fri morning. IFR/LIFR conditions will be
widespread with MTNS OBSCD. Pac front will begin to spread rain into
interior Norcal by Fri afternoon N of I-80...and then into the I-80
and US-50 corridor around 22//00Z.