Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 180400

900 PM PDT Thu Apr 17 2014

Weak Pacific front will move through tonight bringing some isolated
light showers...north of Interstate 80. Isolated showers and
thunderstorms are possible over the Sierra Nevada Friday. Dry
weather over the weekend with continued above normal temperatures.
Cooling next week with unsettled weather late Monday through midweek.


.Short Term Discussion (Tonight through Sunday)...
Weak pacific frontal system moving into the NW portion of the
forecast area this evening with light showers indicated along the
baroclinic zone. Low level convergence ahead of the main front
sparked some deep moist convection over portions of Tehama and Butte
county earlier with several isolated thunderstorms with heavy rain
resulting. These stronger cells have dissipated but a few weak
showers continue along the convergence over Eastern Tehama/Butte and
Western Plumas counties. Surface front will continue to elongate and
weaken tonight, while associated upper trough moves through
overnight into early Friday. This will keep a threat of a few light
showers from about KOVE northward in the Central Valley through late
this evening and in the foothills and mountains north of I-80
tonight into early Friday.

Upper troughing lingers over the Sierra Nevada Friday with models
indicating some instability for potential isolated showers or
thunderstorms, mainly in the afternoon. Little change in high temps
for Friday then upper ridging gradually builds over Interior NorCal
this weekend with minor warming and dry weather. High temps over the
weekend expected mostly in the lower 80s for the Central Valley with
60s to 70s for the foothills and mountains.


.Extended Discussion (Monday through Thursday)
Pattern change starts Monday with cooler and wetter weather on
the way. The ECMWF, GFS, and GEM models are in very good agreement
for the main arrival of a large upper low from the Gulf of Alaska.
Although light mountain showers could start Monday morning, the
brunt of this system will start impacting NorCal Monday evening.
Showers will spread southward across our CWA Monday into Tuesday.
Have kept the mention of slight thunderstorm chances Tuesday as
forecast instability appears favorable for the valley. Cooler
temperatures will be noticeable as valley highs go from the low
80s on Sunday cooling to mid-upper 70s on Monday and mid 60s-low
70s by Tuesday. Those cooler temps on Tuesday will continue into
Wednesday with lingering showers. Upper ridge will build back into
the area Thursday with warmer temperatures...but north winds may
occur as the ridge approaches.



Predominantly VFR conditions next 24 hours. A passing cold front
will bring isolated rain showers along with gusty north winds early
this evening from KOVE northward. Local MVFR possible in showers.
The front should move east of the area by 6-9z, allowing skies to
clear and winds to become calm. Light north to northwest winds up to
10 kts expected for most Valley locations for the rest of tonight
and into tomorrow with VFR conditions. -DVC


.STO Watches/Warnings/Advisories...

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