Area Forecast Discussion
Issued by NWS Sacramento, CA

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846
FXUS66 KSTO 252200
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
300 PM PDT Tue Jul 25 2017


.SYNOPSIS...
Slight chance of afternoon showers or thunderstorms across
portions of the northern mountains Wednesday. Near normal
temperatures today then dry and warmer Thursday through the
weekend.

&&

.DISCUSSION...
581 DM upper low centered near Fort Bragg will be main weather
feature influencing Interior NorCal over the next 24 hours.
Satellite imagery showing some TCU over the mountains of Eastern
Shasta county including the Lassen Park area earlier this
afternoon, but is diminishing now given amount of low and mid
level dry air present. Afternoon temperatures running several
degrees cooler in most areas expect invof Delta where flow through
the Strait is a little weaker compared to 24 hours ago. Highs
today expected to top out right around normal values for this time
of year.

Upper low forecast to remain quasistationary overnight then slowly
progress to the ENE Wednesday as it begins to fill. NAM elevated
instability progs keeps some increased 700-500 MU CAPE and TT
above 30 over Eastern Shasta including Lassen Park area and
Coastal range tomorrow, but only a slight chance for deep moist
convection given limited available moisture. Temperatures rebound
up a few degrees Wednesday as Delta influence and synoptic cooling
weaken.

Heights increase over the area Thursday as upper ridging from the
Desert SW expands NW towards NorCal. Dry weather expected
Thursday as triple digit heat returns across much of the Central
Valley. Temperatures are forecast near to a few degrees warmer
Friday as we are sandwiched between deep troughing in the EPAC and
the 4 corners high.

PCH

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)
Not much change to the extended forecast. Temperatures still
expected be 5-10 degrees above normal as high pressure over the
Four Corners region strengthens. The interior NorCal valley will
have widespread triple digit heat into the first part of next
week. Models still disagree about where monsoonal moisture could
be advected northward next week. The ECMWF keeps dry conditions in
our CWA while the GFS indicates moisture along and east of the
Sierra crest.

&&

.AVIATION...
VFR conditions the next 24 hours across interior NorCal. Winds up
to 10 kt at TAF sites. Gusts 20 to 30 kt near the Delta.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$



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