Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
400 am PST Wed Nov 26 2014
dry and mild weather is expected through Thanksgiving as high
pressure covers the region. Rain is expected to return to the
region by late Friday and continue into early next week. Snow
across the mountains is likely to cause travel difficulties for
the Holiday weekend and into early next week.
mainly clear skies across the interior of norcal early this
morning as only a few high clouds are managing to spill through
the ridge. Early morning temperatures are pretty similar to
readings of 24 hours ago and range from the 20s in the colder
mountain valleys to the upper 30s to mid 40s in the Central Valley
with 50s in the thermal belts. Patchy valley fog will also be
possible through mid-morning.
Strong ridging will maintain dry and mild weather for the region
through Thanksgiving. We'll begin to see more high clouds on
Thanksgiving as the ridge axis shifts east into the Great Basin.
Precipitation chances will gradually spread south on Friday (but
will likely remain north of I-80) as deeper moisture (tpw over an
inch) moves up from the southwest and warm advection increases.
Frontal system is forecast to push southward into the northern San
Joaquin Valley Saturday as the upper jet shifts south. The higher
elevations of the northern Sierra may begin to see a little
More significant potential impacts will hold off until late in the
weekend and early next week.
Extended discussion (sunday through wednesday)...
development of a deep, closed upper level low off the California coast
late this Holiday weekend threatens to bring significant
Rain/Mountain snow to interior norcal into early next week. The
NCEP gefs shows a 70% probability of at least 1 inch of mountain
precipitation, and a 40% probability of at least 2 inches. The
GFS/ec/Gem all show warm frontal type precip Sunday with the main
low still west of 130w.
Mid range models have been showing several inches of rain
from Saturday through monday; however, the amounts/timing could
be in jeopardy as the models have shown signs of diverging. The
GFS and Gem show the low slowly filling and progressing inside
130w on Monday with decent amounts of precipitation. On the other
hand, the ec cuts off the low west of 130w with little movement
eastward until Tuesday. While a multi-day precip event for norcal
exists, model differences in timing could result in greater,
lesser, or delayed results/impacts. In spite of the ec diverging,
we have kept precipitation amount relatively constant. For now,
the heaviest precip forecast is still expected to occur from
Sunday night through Monday. Significant snow may accompany this
wet period. Light snow accumulation may occur down to 4500-5000 ft
and 5-10 inches of snow may accumulate above 6000 ft with 12-36
inches above 7000 ft. The higher end amounts would likely occur
over Lassen park and into western Plumas County. Jclapp
early morning patch IFR/LIFR fog/stratus conditions in the
Central Valley and mtn valleys/basins. Dewpoints increased from
yesterday, so expect to see more fog. Most will be patchy and
relatively shallow. Jclapp