Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 012312
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
312 PM PST Sun Feb 1 2015
Light precipitation possible in far northern portions tonight through
Tuesday night. Above normal temperatures still expected the rest
of the week. Night and morning fog possible in the Central Valley
into early next week. Increasing confidence in wet pattern
returning late in the week.
.Short Term Discussion (Today through Wednesday)...
Ridge of high pressure flattens the next few days bringing cooler
temperatures (but still above normal) and a chance of light
precipitation to the Northern Sacramento Valley and surrounding
mountains. Temperatures this afternoon are cooler than yesterday
(by around 2 to 12 degrees) due to a cooler airmass and mid and
high clouds moving through along with southerly winds. The most
cooling (around 12 degrees) is in the Northern Sacramento Valley which had
some downslope warming with Northerly winds yesterday (and
southerly winds today) and the other locations with the most
cooling was near the Delta region (e.g., Vacaville and Fairfield) which had
some dense fog this morning. Patchy fog is expected to return to
areas around Sacramento, Delta and the Northern San Joaquin Valley
again the next few mornings. Temperatures are expected to be
similar tomorrow with highs in the mid 60s in the Valley and
generally 50s in the mountains, which is about 5 to 10 degrees
above normal for this time of year.
Weak systems moving through the fairly flat ridge will brush by
the north bringing a chance of precipitation tonight into Tuesday
mainly over the Northern Sacramento Valley and surrounding
mountains. Precipitation amounts will be light with a quarter to
half inch over Shasta County mountains and around a tenth of an
inch around Redding to less than a than a tenth of an inch in the
Valley to around Chico and around a tenth to a quarter of an inch
in other mountains north of I-80. Ridge builds up some on Wednesday
ahead of a trough. The ridge will bring a dry day and warmer
temperatures up north with less cloud cover. Patchy Valley fog is
expected again Wednesday morning. The approaching trough may bring wet
weather Thursday into the weekend for Northern California.
.Extended Discussion (Thursday through Sunday)
Confidence remains high that the ridge will finally break down
toward next weekend, bringing in a round or two of stormy weather.
The first round of precipitation could begin to bring
precipitation as early as Thursday night, but the best chance of
precipitation holds off until later Friday. With a strong moisture
tap and decent dynamics, this has the makings of a good
Longer-range models are starting to hone in on a solution that
brings a 2nd wet system on NorCal later Saturday into Sunday.
Computer models havent been nearly as consistent with this 2nd
system as they have been with the 1st, so confidence is lower.
We`ll need to pay attention to this potential 2nd one though, as
it could end up as wet as the 1st.
Mainly VFR conditions this afternoon, except some localized MVFR
in the San Joaquin Valley. Expect conditions to deteriorate to
IFR/LIFR again in the Valley generally south of KMYV between
06-18z. Winds will remain generally light.
A weak system will pass to the north tonight through Monday.
Precipitation should remain mainly along the mountains with
VFR/MVFR flying conditions.