Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 292300
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
300 PM PST Thu Jan 29 2015
Dry weather expected into the weekend with night and morning
valley fog and above normal temperatures. Some breezy wind
possible Friday into Saturday. A slight chance of showers northern
areas Monday...otherwise mostly dry weather likely to continue
through mid week.
Satellite imagery showing some CU developing along mountains of
Interior NorCal this afternoon in response to elongated upper
trough/low moving into the area. HRRR/local WRF-ARW showing
potential for some showers from Sierra Nevada crest eastward and
on the west slopes, south of our portion, near Yosemite through
this evening. Mostly clear skies expected for Interior NorCal
overnight with some fog returning for the San Joaquin Valley
overnight into Friday morning.
Closed upper low deepens over SoCal Friday as EPAC upper ridging
builds into the PacNW. At surface, inverted trough extends
northward along the CA coast into OR as surface high builds into
the Great Basin. This pattern will result in some breezy N to E
winds over Interior NorCal Friday. Gradient suggests wind speeds
will generally remain below advisory criteria. Increase in low
level northerly flow Friday morning may help limit valley fog
development or allow for faster clearing for areas that do have
Upper ridging builds into NorCal over the weekend with some breezy
wind continuing into Saturday, strongest along the west side of
the Sacramento Valley. Some patchy fog possible in our portion of
the San Joaquin Valley Saturday morning but should be limited.
More widespread valley fog possible Sunday under lighter surface
wind and increased subsidence. Above normal temperatures continue
over the weekend with highs ranging from upper 50s to lower 60s in
the Northern San Joaquin Valley to lower to mid 70s in the
Northern Sacramento Valley. Highs in the mountains and foothills
forecast in the 50s and 60s.
.Extended Discussion (Monday through Thursday)
Models differ slightly in amplitude of ridging over NorCal
Monday...with Euro just flat enough to bring disturbance and
moisture into far northern California and the GFS keeping things
mainly dry. Will keep slight shower chances Coastal Range and
Shasta county Monday/Tuesday to blend with Euro and surrounding
offices. A stronger system is possible late Thursday into
Friday...especially over northern areas(Coastal Range/Shasta
county/Nrn Sierra). Temperatures will range from the low/upper
60`d through the period warmest north.
VFR conditions with generally light winds are prevalent this
afternoon across northern California. Expect some patchy dense fog
to redevelop again tonight into Friday morning, mostly likely
around KSCK but also possible near Sacramento TAF sites.
Light north winds will increase to 5-15 kt by mid to late Friday
morning. Local gusts up to 25 kt will be possible along the
northern and western Sacramento Valley after 18z Friday.