Weather Service Report


651 
FXUS66 KSTO 222210
AFDSTO

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

.SYNOPSIS...
NorCal's first triple digit heat of the season will continue for
portions of the Central Valley today and 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 (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 tomorrow as 
northern portions of it progress into the Great Basin, ahead of 
advancing short wave system. Little change expected in max temps 
Tuesday with possible exception of slightly more Delta breeze 
influence into the Southern Sacramento Valley. High temperatures 
tomorrow 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.

&&

$$

Return to Home page


Western Regional Climate Center, wrcc@dri.edu