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FXUS66 KSTO 191703

958 AM PDT Sat Apr 19 2014

A weak system well to the north will bring slightly cooler
temperatures today. Building high pressure on Sunday will result
in northerly winds and warmer temperatures. A stronger Pacific
trough will approach the coast Monday bringing increasing clouds
and a chance of rain and higher elevation snow on Monday night and
Tuesday. Some areas may also see a chance of thunderstorms. Weak
high pressure will dry things out some Wednesday and Thursday but a
threat of precipitation will continue across the far northern
sections of the state. Another trough will bring another chance of
rain to all of interior Northern California Friday into Saturday.


.Short Term Discussion...
A system is moving through the Pacific Northwest today bringing
some clouds and cooler temperatures today with synoptic cooling and
onshore flow. The Delta Breeze is blowing this morning with SF0-SAC
gradient around 3 mb and SUU winds SW around 30 mph. Temperatures
today will warm up into the upper 70s to low 80s in the valley and
low 70s in the delta and 50s and 60s in the mountains. Weak ridge
over the area tomorrow as this systems shifts east and a stronger
system approaches the west coast. This will bring warmer
temperatures and some northerly winds Sunday. The onshore flow will
turn Northerly tonight as surface high pressure moves into the
Pacific Northwest. Although the MFR-SAC gradient expected to only be
about 7 MB and 925 MB winds only about 20 kts so Northerly winds not
expected to be very strong. The Northerly downslope winds will keep
some overnight temperatures warmer tonight than last night.
Temperatures Sunday afternoon will warm into the mid 80s in the
valley and around 80 in the delta and 60s and 70s in the mountains.
Temperatures cool down on Monday into the mid to upper 70s in the
Valley and 50s and 60s in the mountains with the trough off the
California coast bringing synoptic cooling and onshore flow.
Temperatures cool down to below normal for this time of the year on
Tuesday with highs in the mid 60s to around 70 in the valley and 40s
and 50s in the mountains as the trough moves through the area.
Precipitation may begin over the Coastal range and Shasta county
Monday afternoon and spread southeast across the area by Tuesday
morning. The 12z NAM is much quicker with the trough and moves it
east of the area by Tuesday afternoon making convection less
favorable. The GFS is a little slower with a piece of energy moving
through Northern California Tuesday afternoon. The current forecast
goes with the GFS solution but may decrease precipitation amounts
and pops for afternoon forecast with drier NAM. Snow levels will
start out around 7000 ft Monday night and lowering to around 5000 ft
Tuesday morning. Not a lot of snow or precipitation is forecast at
this time but a couple of inches of snow near pass level look

.Extended Discussion (Wednesday through Saturday)

Slight warming trend begins on Wednesday as the upper low from
Monday and Tuesday moves east of our region and ridging re-
develops along the west coast. This ridge is not forecast to be
strong so lingering light showers are possible over the northern
mountains Wed & Thurs. Additional warming on Thursday as valley highs
return to the mid-upper 70s. However, by Friday and into the
weekend, another upper trough will move across our CWA bringing a
return of more widespread precipitation and cooler temperatures.



VFR conditions will continue next 24 hours for Central Valley TAF
sites. Generally light winds over the northern Sacramento Valley,
with winds 12-15 kt with local gusts to 21 kt expected from KSMF
southward through this afternoon. Breezy/windy in the Delta region
WS winds 15-25 kt gusting to around 35 kt.


.STO Watches/Warnings/Advisories...


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