Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 230356
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
856 PM PDT Mon May 22 2017

.SYNOPSIS...
NorCal`s first triple digit heat of the season will continue for
portions of the Central Valley again on Tuesday. Cooling trend
begins Wednesday with near to slightly below normal temperatures
by Friday. Isolated late day showers or thunderstorms possible
over portions of the mountains Tuesday, Wednesday and again
Friday.

&&

.Discussion...
Temperatures are running a few degrees warmer this evening over
the interior but have trended slightly cooler in the Bay Area.
Winds through the Delta are light and are expected to remain
light tonight and for most of the day on Tuesday. Temperatures
should remain near todays high`s on Tuesday for most areas with
only minimal cooling in the Sacramento region. Winds will start to
increase in the Delta late in the day but will probably not have
that much impact on Tuesday`s daytime high temperatures inland
outside of the Delta. Stronger winds through the Delta with
better cooling for the Sacramento region will occur Tuesday
evening. Further inland it will still be slow to cool off again at
night.

.Previous Discussion (Today through Thursday)
High amplitude upper ridge over the EPAC extends inland resulting
in well above normal temperatures over Interior NorCal. Afternoon
temps running upwards of 5 degrees higher than 24 hours ago.
Marine layer has dropped below 1000 ft and the Delta breeze is non
existent attm. High temperatures expected above the century mark
in the Northern Sacramento Valley and possibly at select spots in
the Northern San Joaquin valley this afternoon.

Upper ridging gets suppressed slightly over NorCal Tuesday as
northern portions of it progress into the Great Basin, ahead of
short wave system tracking towards the PacNW. Little change
expected in max temps Tuesday with possible exception of slightly
more Delta breeze influence into the Southern Sacramento Valley.
High temperatures Tuesday continue above the century mark in the
Northern and Central Sacramento Valley. Mid to upper 90s expected
for the Southern Sac/Northern San Joaquin portions of the Central
Valley. Slight increase in available moisture and instability
Tuesday over the Sierra Nevada, south of US-50, may result in
isolated afternoon showers or thunderstorms.

Marine layer deepens Tuesday night as upper low approaches and
onshore flow increases. Models showing strong flow through the
Delta developing overnight Tuesday into Wednesday. Weak cold
front progged to drop from the PacNW across northern portions of
CA on Wednesday as short wave system digs into the Great Basin and
expands westward. This will begin a cooling trend Wednesday that
continues through the remainder of the week. Slight chance of
showers or thunderstorms possible over the Shasta and Coastal
mountains Wednesday afternoon into evening.

Cooling continues Thursday with more stable AMS. 80s expected
throughout the Central Valley with 70s in the Delta and
foothills, and mainly 50s to 60s in the mountains.

PCH

&&
.EXTENDED DISCUSSION (Friday THROUGH Monday)

A ridge of high pressure will be building back into NorCal for the
holiday weekend and that is going to bring quiet weather with
warming temperatures. We will see highs on Friday in the low to
mid 80`s but will be warming to near 100 for some by Sunday. A
Delta influence Friday and Saturday will keep southern areas a bit
cooler but it will start to weaken Sunday and Monday. Some weak
instability will build into the higher elevations Saturday through
Monday during the afternoon and evening and that will lead to
just an isolated t-storm chance. A short wave trough approaches
from the west later Monday and that will bring the chance for some
clouds but we look to stay dry.

-CJM
&&

.AVIATION...


VFR conditions the next 24 hours at valley TAF sites. Winds will
be variable under 10 knots.

-CJM
&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$



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