Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 122155
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
255 PM PDT Sat Jul 12 2014

.Synopsis...
Warmer daytime temperatures into Monday then slightly cooler into
mid-week. A chance of Sierra crest thunderstorms returning Monday
spreading northward on Tuesday into mid-week. A diminishing shower
threat towards the end of the week as the upper level flow becomes
more westerly.

&&

.Discussion...
Clear skies across most of the region this afternoon as high
pressure builds. Satellite imagery indicates scattered cumulus
development is occurring over the northern Sierra with a few
popping over the Coast Range. So far, appears that convection is
being capped off over the northern Sierra as deeper convection has
been limited to far NE CA. There is a slight chance that a
thunderstorm or two may develop late in the day near Mt. Lassen.

Temperatures have begun to warm across the region today in
response to the building ridge. The bigger increases (5-10
degrees) have been further inland across the northern Sacramento
Valley and in the mountains while a continuing Delta Breeze has
helped to temper warming across the southern Sacramento Valley,
Delta and northern San Joaquin Valley (up 2-4 degrees).

The ridge will continue to build across the region into early next
week with warming temperatures the main impact for the area. A
strong short-wave is forecast to move over the top of the ridge
into the PacNW on Sunday but will have little impact on NorCal`s
weather as active convective weather will be well to our north.

Valley temperatures will warm to around 100-105 on Sunday, then
a little warmer temperatures are expected for Monday. Some
moisture is forecast to begin moving northward again by Monday
leading to another threat for late day thunderstorms along the
higher elevations of the northern Sierra.

Deeper moisture is forecast to be drawn further north into NorCal
on Tuesday spreading the chance of thunderstorms northward into
the northern mountains. This will have some effect on max
temperatures as the clouds will limit insolation, and will also
lead to milder overnight low temperatures.

&&

.Extended Discussion (Wednesday through Saturday)...
High pressure will remain over the Desert Southwest and weak low
pressure over the the Eastern Pacific. With southeast flow aloft
over NorCal, monsoonal moisture will likely work its way up the
Sierra, with thunderstorms possible along interior NorCal
mountains Wednesday and Thursday. Models are hinting at the
possibility of nocturnal convection over the mountains as well.
This pattern is often favorable for showers to work their way down
the mountains into the lower elevations, we`ll need to monitor
that possibility closely. Upper level flow becomes more westerly
by late next week, which should push monsoonal moisture to our
east.

Temperatures should be within a few degrees of normal through the
extended period. Dang

&&

.Aviation...
Mainly VFR conds the next 24 hours across int NorCal. IFR conds
possible along the wrn Delta tngt into early Sunday. South to west
winds 5-15 kt across Valley TAF sites will become light tngt. Near
the Delta...SW winds 15-25 kt will cont. Dang

&&

.STO Watches/Warnings/Advisories...None.

&&

$$



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