Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 301640
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
840 AM PST Sat Nov 30 2013
Warm and dry weather will continue through the weekend. A cold low
pressure system early next week may spread light snow across the
mountains, possibly down to the foothills. Freeze conditions in
the valley will be possible mid to late next week.
Strong ridge building into NorCal will continue the dry and mild
weather across the region through the weekend. Band of high clouds
that has been moving across the region this morning will slowly
shift south and east through the day. Temperatures today expected
to be similar to Friday`s most areas. No updates.
.Previous Discussion (Today through Tuesday night)...
Strong ridge with center along 140W will build inland over the
weekend with maximum 5h heights and warmest air over our area on
Sun. Some high cloudiness will spill over the ridge and into the
forecast area mainly on Sat, before the ridge flattens late Sun
and Mon in advance of the deepening British Columbia Low. Of
course, the potential exists for some areas of fog this weekend,
much of out it shallow in nature.
Max temps could become quite warm this weekend especially on Sun
across the northern and western portion of the Sac valley due to
adiabatic warming effects from Nly winds. The Nly wind flow will
become more pronounced on Sun, but the flow will not be too strong
warranting wind advisories, just the trajectory of the flow will
be ideal for adiabatic warming.
The potential exists for some of our sites to flirt with record
max temps this weekend. Some of the record maxes seemingly are
out-of- reach such as RDD (82)...SUU (78) and Mod (75) for Sun.
The area with the greatest potential of reaching any records
would be the southern Sacramento Valley and Delta areas.
Of more interest is the strong, cold storm system coming down from
British Columbia Monday night into at least Wednesday. A negative
cold anomaly (colder than normal) is setting up for late Tuesday
and beyond, while a negative precipitation anomaly (drier than
normal) is setting up as well. Good orographic lift appears to be
present early Tuesday prior to the coldest air arriving, and this
may generate some decent precipitation over the Sierra. Snow
levels are expected to be 3000 ft up north to 3500-4000 ft over
the main portion of the Sierra by midday Tuesday, and lowering in
the afternoon and overnight. The best dynamics with the most
available moisture looks to be Tuesday with fairly high snow
ratios. Snow amounts and snow levels can be fickle this far out
with these types of systems. The Low track, available moisture,
and airmass temperature involved will determine snow amount and
elevations. Right now, 3-5 inches are forecast above 6500 ft with
lighter accumulations down toward the Sierra foothills Monday
night through Tuesday night, which is an increased amount from our
last forecast. Stay tuned... JCLAPP
.Extended Discussion (Wednesday through Saturday)...
Showers are possible in the Burney Basin Region and down along the
Sierra on Wednesday as a piece of energy may move down along the
back side of the trough over the western U.S. Snow levels may drop
down to around 1500 feet but not much accumulation is expected due
to limited moisture. Cold temperatures and Breezy and gusty
northerly winds are expected Wednesday as surface high pressure
moves into Oregon. MFR-SAC gradient may be around 10 mb Wednesday
morning for Northerly winds of 15-30 mph...especially along the
west side of the valley. The gradient turns more easterly on
Thursday bringing gusty winds along favored NE_SW oriented canyons
and passes. Temperatures are expected to be 7 to 15 degrees below
normal for this time of year with high temperatures in the upper
40s to low 50s in the valley and 20s to mid 30s in the mountains.
Minimum temperatures drop down in the 20s in the valley and single
digits to teens in the mountains Wednesday and Thursday mornings.
This will bring the potential for the first hard freeze in the
Generally VFR/MVFR conditions expected over interior Northern
California the next 24 hours with some high clouds moving through
the area. MVFR conditions due to BR/HZ will continue most of the
day at KSCK. Dang