Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 220548
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
945 PM PST Fri Nov 21 2014

.Synopsis...
The last in a series of weather systems will move into the area
tonight into Saturday, bringing widespread precipitation. A ridge of
high pressure will build back in for the end of the weekend into
much of next week. This will allow for dry weather and above normal
temperatures. Areas of morning valley fog are possible into the
middle of next week with lingering moisture and light winds.

&&
.Discussion...
Rain band finally has moved into our CWA...extending across Wrn
Shasta Co at press time. Extrapolation suggests the forward speed is
about 35-40 kts and by midnite should be along a NE-SW line from
about Quincy-Yuba City-Rumsey...with lighter echoes on the SW flank.
By 4 am...the rain should move into the I-80 corridor. Still looks
as if later tonight and through Sat morning when periods of
moderate-heavy precip occur over the Siernev...then tapering/ending
in the afternoon...although upslope flow will linger some precip
over the Siernev. Pre-frontal winds expected to be the strongest
from 06-18z Sat...and more in the 12z-18z time frame for the I-80
corridor. 925 mbs winds suggest gusts 25-35 kts with the mtns on the
higher end and portions of the valley on the lower end.   JHM


.Previous Discussion...

Latest hi-res guidance in agreement that, for much of the area, bulk
of precip will fall between 6Z-18Z Saturday with this evening`s
commute remaining dry. Forecast generally on track with minor tweaks
made to timing of highest POPs and QPF. PWAT is fairly high for this
time of year with values ranging from 0.75 to 1.5 inches. Forecast
QPF values haven`t changed much from this morning`s forecast with
amounts ranging from 0.10-0.4" in the valley to 0.5-1.5" in the
foothills and mountains. Because of warm nature of system, snow
amounts will be limited as snow levels rise above 7-8K feet by the
time the majority of the precip arrives. Light accumulations
expected only at highest elevations with minimal travel impacts
expected. Other factor with this system will be breezy conditions on
Saturday. Sustained valley winds may be on the order of 15-20 mph
with gusts as high as 35 mph in some locations. Mountain ranges will
see gusts upward of 40-45 mph with higher gusts near the Sierra
crest.

Ridging builds back in over the coast for Sunday into the
beginning of next week. Dry weather is expected with above normal
temperatures. Valley fog certainly possible early Monday morning
with light winds and lingering moisture. CEO

.Extended Discussion (Tuesday through Friday)

Strong ridging will bring dry weather and light winds early next
week through Thanksgiving day. Travel conditions are expected to
be good through that period, except for locally dense fog in the
Valley at times. The light winds and mostly clear skies at night,
along with leftover moisture from recent storms could create good
conditions for fog development, but the exact location and timing
details will have to wait. Temperatures should be quite mild with a
warm airmass, though if fog manages to persist into the afternoon,
those areas could end up being cooler than forecast.

On Friday, models are suggestion a shortwave could bring some
precipitation into the coastal range and northern mountains. The
12z GFS and ECMWF also show this spreading into the northern
Sacramento Valley and the Sierra. have introduced a slight chance
of rain into those areas. Snow levels look to be above pass levels
at this point. EK

&&

.Aviation...

Light precipitation is gradually spreading from north to south into
interior Norcal. Most of the rain/snow occurring 06z. This will
bring widespread MVFR with local IFR cigs/vsbys across NorCal into
Saturday. Light winds for this evening, but southerly winds will
increase up to 15 kts after 06z with gusts 25-35 kts...highest over
Siernev and lowest in the valley.

&&

.STO Watches/Warnings/Advisories...
None.
&&

$$








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