Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 232101

Area Forecast Discussion
National Weather Service Sacramento CA
201 PM PDT Wed May 23 2018


Afternoon and evening thunderstorms possible mainly over higher
terrain this week. These are expected to extend through the
Valley late in the week. Slightly cooler than normal temperatures
continue across most of the region this week warming to above
normal early next week.



Upper level low pressure system shifting eastward has created
scattered showers and thunderstorms across the Sierra this
afternoon as residual moisture continues to be present across
northern California. Breezy conditions for some locations across
the valley with strongest winds in the delta area.

An upper trough currently off the coast will approach Thursday and
move inland late Thursday night into Friday. This will bring the
potential for widespread showers, including across the Valley and
Delta for Friday morning. Some afternoon and evening
thunderstorms are also expected, with unstable conditions from a
cool core low for the mountains. Snow levels will drop enough to
allow some snow at pass levels south of highway 50. Latest model
runs have higher QPF values for the mountains south of highway 50,
and have brough snow accumulations above 8000 feet to between 3
and 6 inches of snow expected. High temperatures trend well below
normal Thursday and Friday. Friday highs across the Valley are
expected to be only in the low 70s, about 10 degrees below normal.

Showers linger across much of the area Saturday morning, then
gradually shift eastward as the upper low exits to the east.
Mountain showers and thunderstorms are possible again in the
afternoon and evening hours. Outdoor planners should have some
contingency plans in case of disruptions from developing storms.



An upper level low will be tracked eastward out of NorCal and will
be replaced by a ridge to start the extended period. This will
bring warming conditions for the second half of the holiday
weekend. Highs on Sunday will be in the mid 80s to lower 90s for
the valley while higher elevations reach the 60s and 70s. Things
look a bit warmer on Monday and we may see our first 90 of the
year in the Sac area. Tuesday will likely be our warmest day in
the period with mid 90`s across the valley and 60s and 70s in the
mountains. Isolated t-storms will be possible in the higher
elevations on Sunday with little to no t-storm threats Monday and
Tuesday. A trough will move into the region mid to late week and
that will bring cooler temperatures along with rain and t-storm
chances to the higher elevations.




VFR conditions are expected at the TAF sites the next 24 hours.
Scattered showers and t-storms over the mountains will continue
through 5z, MVFR/IFR in the vicinity of any this activity. Marine
stratus making it into the Sacramento area looks less likely
Thursday morning but a few clouds around 1000 to 2000 feet will be
possible between 9z and 16z. Breezy southerly winds this
afternoon 10-15 knots gusting to 20 knots will begin to diminish
during the evening but will remain breezy in the Delta.






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