Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 250423
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
923 PM PDT MON AUG 24 2015
Mainly dry weather continues this week with southwesterly flow
across the region. Temperatures will be near normal for late August.
A cooling trend is forecast for this weekend with possible
precipitation across the north.
The region continues to be in between high pressure over the
desert southwest and a low pressure area and a low pressure area
off the coast of Canada. Some high clouds may drift through the
region from the southwest and south at times but conditions are
expected to stay dry through Wednesday. Some high clouds may drift
over the region Tuesday night and Wednesday from the monsoonal
moisture down south.
Slight warming each day through Thursday is expected as the
trough deepens off the coast. Delta breeze should continue each
day and night but it is not looking overly strong. Thursday the
NAM model tries to bring some activity northward along the crest.
Southwest flow looks strong enough to mainly keep activity on the
east side of the crest with perhaps a slight chance for the
west side near Yosemite.
.EXTENDED DISCUSSION (Friday THROUGH Monday)
Cooling trend this weekend with a chance of showers over the Nrn
portion of the CWA. Low pressure off the B.C. Coast forecast to
deepen with the initial wave of energy affecting our CWA late Fri
and Sat. The GFS/ECMWF timing differences during the EFP are
beginning to get resolved with both models spreading some precip
mainly over the Nrn portion of our CWA (N of I-80) during the Fri
nite/Sat time frame. The NAEFS is showing a chance of >=0.10" over
the Nrn Mtns/Nrn Vly area during the successive 6 hour periods
during the Fri nite/Sat morning time frame...with the Reforecast2
data suggesting about a 30-40% chance of >0.10".
The initial wave is forecast to lift out of the area by Sat evening
with dry SWly flow prevailing on Sun. Reinforcement of the trof
should continue the cool wx into Mon with a high degree of
uncertainty as to the 24/12Z GFS` Pops for Mon. Max temps Sat-Mon
are forecast to be several degrees below normal. JHM
SWly flow alf with upr rdg ovr Grt Basin and upr trof ofshr. VFR
conds ovr Intr NorCal nxt 24 hrs exc isold MVFR poss vcnty Wrn Delta
in ST btwn 06z-17z. Lcl SWly sfc wnd gsts to 25 kts ovr hyr mtn
trrn btwn 22z-03z and to 30 kts thru Delta btwn 00z-14z.