Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 231139

Area Forecast Discussion
National Weather Service Sacramento CA
339 AM PST Thu Feb 23 2017

Significant flooding concerns continue as runoff from the recent
rain continues to work its way downstream adding stress to
waterways. A couple of weak but cold storms move through
Friday/Saturday then Sunday/Monday. An extended period of dry
weather starts the middle of next week.


Northern California is under upper level northwest flow between a
low pressure system over the Great Basin and high pressure over
the eastern Pacific. Weak disturbances dropping southeast in this
northwest flow bringing a few showers to the Sierra and foothills
this morning and this will continue to be a threat there today.
The rest of the CWA will see mainly fair skies today under a cool
airmass and cooler than normal daytime temperatures. Friday looks
likely mainly a dry day under weak high pressure. Fair skies in
the morning under a cool airmass will make for a cold morning
Friday. Morning lows will drop into the low to mid 30s in the
Sacramento valley so areas of frost are likely.

Models in fairly good agreement in dropping a cold upper low down
the Pacific Northwest coast during the day on Friday bringing a
slight threat of showers to the northern mountains by the end of
the day. This chance of showers spreads southward overnight Friday
and Saturday as the upper low continues southward off the Norcal
coast. Snow levels with this system will be quite low and forecast
between 1000 and 2000 feet. This is a fairly dry system and the
main low center remains offshore so snowfall amounts at any
elevation will be quite light and therefore have limited impact.
Light snow will be possible well down into the foothills however
with some areas receiving a dusting of snow where snow is
relatively rare. Early Sunday will see a brief break in
precipitation before the next cold system drops down the Pacific
Northwest coast and into Northern California. This system will
track farther inland than the previous system and contain a bit
more moisture. Therefore this system will be a bit wetter but
still overall a fairly low precipitation maker. Some areas of the
Sierra could see a few inches of snowfall. Snow levels with this
system will be a little higher at between about 2000 and 3000
feet. Some minor travel impacts are likely due to the low snow
levels and expect snowfall even over the lower elevation northern
mountain passes.



Large upper trof forecast to push into the Great Basin early next
week leading to a decreasing threat of showers Monday with only a
slight chance of mountain showers Tuesday. Upper ridge then builds
into NorCal Wednesday into Thursday bringing dry weather with
warming temperatures. High temperatures warm into the lower 60s
midweek in the Central Valley.



Lrg upr trof cntrd ovr Grt Basin with NWly flow alf ovr Intr
NorCal. Genly VFR conds ovr Intr NorCal nxt 24 hrs exc sct
MVFR/IFR conds poss ovr motherlode/W slps Siernev in shwrs.
Sn lvls 020-030 amsl.

Flash Flood Watch through Saturday morning for Carquinez Strait
and Delta.


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