Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 222128
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
228 PM PDT SUN MAY 22 2016


.Synopsis...

An upper level disturbance will continue to bring unsettled weather
and cool conditions across NorCal this week. Chances for showers
and thunderstorms are expected for locations north of I-80 tonight.

&&

.Short Term (Today through Wednesday Night)...

Showers have develop in the Sacramento Valley and over the
mountains this afternoon. Most of the activity will remain north
of Marysville through the evening hours. Isolated thunderstorms
will be possible through the early evening hours but overall
conditions will not be as unstable as they have been the last two
days.

A shortwave will rotate along the coast on Monday and should
increase the showers over the region in the afternoon and
evening hours. That shortwave will move over the San Joaquin
Valley on Tuesday. Most of the activity will be focused over the
mountains and Sacramento Valley both days but depending on where
the low sets up on Tuesday the Northern San Joaquin could end up
receiving some showers as well. Thunderstorms will continue to be
possible both days mainly for the afternoon into the evening
hours.

On Wednesday the low moves over Southern California but the
broader low over the west enhances with the center moving over
Idaho. This will keep unstable conditions over the region with
most of the activity continuing to be focused over the mountains
and slight chances over the northern half of the Sacramento
valley. Temperatures will continue to be cooler than normal but
may slowly become a little bit warmer each day.

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)

Long-wave trough forecast to remain over the West during the
extended period. This will primarily impact higher terrain with a
chance for mountain showers during the extended forecast. Models
are forecasting another closed low by the end of the week
bringing another round of cool and unsettled weather for the
region during the Memorial Day weekend. However, details on the
track of this low remain very uncertain. The GFS and ECMWF have
been "flip-flopping" on whether this low will stay north near the
Canadian border or drop south into NorCal. For now, have kept a
slight chance of showers in the mountains until models come into
better agreement.
&&

.AVIATION...

An upper level disturbance will remain over NorCal the next 24
hours. Mainly VFR conditions are expected across Valley TAF sites,
while periods of MVFR/IFR conditions occur over the mountains
in isolated to scattered showers. Surface winds at TAF sites will
be light around 4-10 kts.

&&

.STO Watches/Warnings/Advisories...
None.
&&

$$



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