Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 080557
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
957 PM PST Fri Mar 7 2014
Dry and mild conditions tomorrow. A disturbance will likely bring
precipitation to the region Sunday and Monday. Dry and mild
conditions return for Tuesday through the end of next week.
Upper ridge is over Norcal this evening with clear skies and light
winds. Temperatures at 9 pm are in the mid to upper 50`s at valley
locations which is similar to yesterday at this time. Forecast
lows in the low to mid 40`s are on track and no evening update
will be needed.
Satellite imagery shows a ridge of high pressure moving over the
West Coast. Looking upstream, a large and complex area of low
pressure is circulating along the northern Pacific near 150N.
This will be the next low pressure system, due to arrive late
this weekend. For the time being however, warm conditions under
mostly sunny skies prevail across interior Northern California.
Modest north winds have also developed across the Valley, with
occasional gusts to 20 mph. Temperatures are peaking this
afternoon in the lower 70s across the Valley, with 50s and 60s
over the mountains.
Dry and mild weather with variable cloudiness will continue
through Saturday under the influence of high pressure.
Temperatures tomorrow will be a bit warmer than today, and
roughly 5 to 10 degrees warmer than normal.
The next low pressure system will start to bring precipitation to
the far northern portions of the state late Saturday night, then
slowly spread southward through the day Sunday and into Monday.
At this point, the NAM model looks like an outlier. This system
in some ways resembles the last one in that snow levels will
start out quite high but drop below Sierra pass levels behind the
front Monday. A few inches of snow accumulation will be possible
above 6000 ft or so, with most of the accumulation occurring
Monday. Additionally, it wouldn`t be too surprising to see a few
thunderstorms with this system, both along the front Sunday
evening and behind it Monday afternoon.
.Extended Discussion (Tuesday through Friday)
The upper trof axis (from the Sun/Mon wx system) is forecast to move
Ewd across the Great Basin on Tue (the start of the EFP) with drying
cyclonic flow prevailing over interior Norcal. Due to 5H heights
rises and pressure rises over the Pac NW...breezy Nly to NEly
katabatic winds will develop over interior Norcal. This will pave
the way for the amplification of the West Coast ridge through the
middle of next week with unseasonably warm conditions. Daytime
highs under the influence of the ridge will be well above normal
(5-10 deg) under fair skies.
The migratory longer wave Gulf of AK (GOA) trof is forecast to
result in a positively-tilted ridge axis over the Pac NW and Nrn
Rockys. The transition to anticyclonic flow will reduce the
pressure gradients resulting in lighter winds by the middle of the
week. However...the effects of the longer wave trof may result in
some modest cooling over the Nrn zones...but with little chance
of precip in our CWA...and mostly light amounts over the Pac NW.
The models handle the effects of this trof a little differently
with the 07/12z GEM/ECMWF similar with a secondary trof moving
into the Pac NW on Thu nite/Fri flattening the ridge and bringing
precip down to the CA/ORE border...then followed by more ridging
during the day on Fri. Meanwhile...the GFS maintains a stronger
ridge. At this time...we have spread some clouds into our CWA with
the prospects of a weakening/flattening ridge but maintained a dry
forecast in our CWA as the prospects for precip in our CWA look
like the proverbial long-shot. JHM
VFR conds ovr Intr NorCal nxt 24 hrs. Lcl NE-E sfc wnd gsts up to
30 kts ovr Siernev with isold stgr gsts ovr hyr rdgs poss ovngt
into Sat mrng.