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Area forecast discussion
National Weather Service Sacramento California
309 am PDT Thu Oct 17 2019



Synopsis...
light showers northern mountains and northern Sacramento Valley
this morning as a weak frontal band moves through with another
round of light showers northern mountains on Saturday. Otherwise
dry through the extended period. Below normal daytime temperatures
through the weekend then above normal temperatures next week as
high pressure moves across the region.

&&

Discussion...
weak frontal band currently moving through norcal bringing light
showers to the northern Sacramento Valley and surrounding
mountains. So far, precipitation amounts of been on the order of a
few hundredths of an inch. Associated weak upper trough is
forecast to move into the western Great Basin by this afternoon as
high pressure begins building over the West Coast. May see a
slight threat of showers over the northern Sierra this afternoon
as norcal transitions from cyclonic to anticyclonic flow. Cool air
filtering in behind the front will bring a significant cool off
today with daytime highs forecast to drop to several degrees below
normal for this time of year. Flat high pressure over the West
Coast on Friday will keep conditions dry but high clouds are
likely to slide over the region. Only a slight warming is expected
most areas.

Models in good agreement in bringing another weak disturbance
through the Pacific northwest and norcal on Saturday. This will
bring a threat of light showers to the northern mountains during
the day. More cooling is expected with daytime highs over the
northern Sacramento Valley dropping to 10 or more degrees below
normal. This weak disturbance moves quickly east of the region
with the precipitation chances ending by Saturday evening. High
pressure starts rebuilding on Sunday bringing a little warming but
daytime highs are still expected to remain below normal.

&&

Extended discussion (monday through thursday)...

Ensemble solutions remain in fair agreement that a building high
pressure will result in warmer conditions next week. Daytime
highs are expected to be 5 to 10 degrees above seasonal normals,
with widespread low to mid 80s in the valley. The strengthening
ridge of high pressure will keep stable conditions over interior
norcal. Models indicate that locally breezy northerly to easterly
winds could be possible around the middle of next week as pressure
gradient tightens.



&&

Aviation...

Precipitation will move outside of the forecast area between
12z-14z Thursday. Local northwesterly wind gusts 15-20 kts
southern terminals 18z Thursday - 00z Friday. Otherwise,
sustained winds generally below 12 knots.

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Sto watches/warnings/advisories...

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