Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 170558
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
958 PM PST Sun Nov 16 2014
Dry weather is expected for most of the area into the middle of
the week when the potential for widespread precipitation arrives.
The possibility of periods of wet weather continues into next
Skies have turned mostly clear...as high clouds struggle to move
over upper level ridge. Updated forecast to reduce cloud cover
overnight. Otherwise...current forecast is on track.
Amplified upper ridge remains just off the west coast this
afternoon. Plenty of high-level moisture moving through the ridge
resulting in plentiful high clouds across the interior of NorCal.
Northeasterly surface pressure gradients have weakened from this
morning, however, still seeing light northerly winds down the
Sacramento Valley (especially the west side) with locally gusty
northeast winds of around 20-30 mph in the northern Sierra and
parts of the coast range.
Relatively cool and drier airmass has moved into NorCal in the
wake of yesterday`s cold front. Most locales are running about 2-7
degrees cooler than 24 hours ago while dew points are lower by
around 20-30 degrees. Overnight lows tonight are expected to be a
little cooler than this morning`s, and despite the high clouds,
coolest spots in the Central Valley will likely dip down into
the mid 30s early Monday morning.
The dry pattern will continue through the early portion of the
week. Models continue to project a trough displacing the ridge by
mid-week, but the trend is for a slower system. Precipitation may
begin Tuesday night and peak on Wednesday. For this period,
rainfall amounts in the mountains to around a third of an inch are
expected, up to around a tenth of an inch in the Valley. Snow
levels should drop below pass levels during the day Wednesday,
but snowfall amounts are expected to be light with little impact.
.Extended Discussion (Thursday through Sunday)
Medium range models bring next frontal system inland Thursday but
are different with timing and strength of this storm. 12Z EC is
significantly wetter than the GFS/GEM and thus forecast has leaned
more towards the latter solutions. GEM is slower with progression
of this wave, while the GFS and EC bring weak upper ridging into
the CWA Friday. The break is short lived as the next system is
forecast to impact Interior NorCal Saturday. The EC again shows
significantly more QPF with this storm than the GFS, while the GEM
looks to be somewhere in between. Uncertainty in the forecast
continues to increase late in the period as the 12Z EC/GEM bring
another wave through Sun while the oper GFS and NAEFS guidance
suggest decreasing threat of showers Sun into Mon under increasing
NWly flow alf as upr rdg conts alg W Cst. Mnly VFR conds ovr Intr
NorCal nxt 24 hrs exc lcl IFR/LIFR poss in ST/FG alg E side of San
Joaquin Vly tngt into Mon.