Area Forecast Discussion
Issued by NWS Sacramento, CA

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116
FXUS66 KSTO 272331
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
431 PM PDT WED APR 27 2016

.Synopsis...
Scattered showers and thunderstorms through early evening, some of
them severe. Light snow accumulations over the higher elevations
of the NorCal mountains tonight. A little breezy behind this
system on Thursday, then dry and warmer.

&&

.Discussion...
An upper level level trough with a surface cold front and cool
air aloft has brought very unstable conditions with scattered
showers and afternoon thunderstorms. As expected, Some of the
thunderstorms have dropped large amounts of small hail and heavy
rain over portions of the northern San Joaquin and southern
Sacramento Valley. Large amounts of small hail caused several mobile
home carports to collapse in Oakdale. Funnel clouds have been
observed in multiple locations. Law enforcement reports a possible
tornado touchdown near Waterford in Stanislaus County. We will be
investigating further see if there was a confirmed touchdown.

The most favorable timing for thunderstorms is winding down,
though several storms continue in the Sacramento area and
southward. Low pressure is centered over the Sacramento area, with
slow moving storms rotating around the low. Some of these storms
near Sloughhouse and Rancho Murieta have been dropping heavy rain
over a period of time. Rancho Cordova received about 0.82 inches
of rain in about an hour. Heavy rain has caused ponding on roads
in some spots and and could lead to local flooding. Motorists
should avoid driving through water; "Turn around don`t drown!"

Convection over the Valley will diminish after sunset, with some
lingering showers in the mountains. Some mountain snow is falling,
and there could be a few inches of snow over the Sierra passes
this evening. Travelers over mountain passes should use caution.

Some afternoon thunderstorms may develop over the Sierra Thursday
afternoon, mainly south of I80. Drier and much warmer temperatures
are expected elsewhere, reaching around 80 in the Valley. This
warming will continue through the weekend, with Valley highs
approaching 90 on Sunday.

EK

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)

A ridge of high pressure will dominate the long term forecast
period with warm temperatures and quiet weather. The strongest
portion of the high pressure system will be Sunday and Monday,
which as a result, will bring above normal temperatures to the
region. The Valley could see temperatures in the mid to upper 80s,
which would be 10 to 15 degrees above normal for this time of
year.

A higher amplitude trough of low pressure will slide down into the
eastern Pacific just off shore of California Monday and Tuesday.
High temperatures will cool slightly, but ranges will still be
around 5 degrees above normal. Some slight chances for showers are
possible along the Coastal Range, but otherwise no significant
weather or precipitation is expected during the long term period.
&&

.AVIATION...

VFR conditions are expected at the terminals for the next 24
hour period.

Winds will be light out of the south and will generally shift to
the west or northwest direction Wednesday night after an upper
level disturbance moves through the NorCal region. There could be
a few wind gusts during the afternoon hours, mainly for the
Stockton terminal. Showers and isolated thunderstorms are
possible with the vicinity of the terminals, but confidence of
direct influence is lessening at this point with short term model
guidance keeping the Valley mostly dry.
&&

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

$$



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