000
FXUS66 KSTO 241022
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
322 AM PDT Sun Jun 24 2018

.SYNOPSIS...
Cooler in the Delta area today, while inland areas remain hot and
dry. Temperatures return to near normal beginning Monday and
through the rest of the week.

&&

.DISCUSSION...
The northerly pressure gradients, over 10 mbs at press time, are
forecast to decrease rapidly into the 3-4 mbs range by 18z today.
This will occur as low pressure over the Rockys moves into the
central Plains by the end of the day and high pressure moves over
Norcal. This will bring an end to the desiccating Nly barrier jet
winds that Staudenmaier (1994) and Mathews & Juskie (2005) have
documented in WRH TA-Lites as having an impact on wind advisories
and red flag warning considerations. These winds helped the rapid
spread of the Stoll, Pawnee, Land and Bascom wildfires in our CWA
on Sat. The Lane and Pawnee wildfires were showing some "hot"
satellite signatures through the night.

Already seeing signs of a healthy onshore gradient developing from
SFO-SAC at 2.5 mbs at 09z, and a return of the Delta Breeze to SUU
of 14 kts. Satellite shows a return of stratus to the SFO Bay area
with the Ft Ord profiler showing the marine layer deepening to
nearly 2 kft just past midnight. These are indications of some much
cooler air spreading into the Srn Sac Vly today which should keep
max temps below triple digits. Thus, have removed zone 17 from the
heat advisory.

Still a hot day away from the Delta as the ridge axis moves over the
region today, although areas away from the Delta will finally see
some cooler air spreading over their areas tonight and Mon. Expect
some stratus to move towards SUU Mon and Tue mornings. Will have
to watch for how much the marine layer deepens Mon/Tue mornings
for a potential stratus intrusion into the Srn Sac Vly.

Seasonable wx returns to the CWA Mon as another Pac NW trof provides
onshore flow and some cooling. This will be followed by slight
warming on Tue as high pressure from the Desert SW builds Nwd. Then
a slight cooling trend on Wed as another trof moves across the Pac
NW.   JHM

&&


.EXTENDED DISCUSSION (Thursday THROUGH Sunday)

Broad upper troughing moves through Thursday then Interior NorCal
sandwiched between EPAC upper ridge and downstream trough. Ridge
remains offshore through the weekend limiting amount of interior
heating. Attm, high temperatures expected to be above normal
through the extended, but not excessively hot with 90s expected
in the Central Valley and 70s to low 90s for the mountains and
foothills. Dry weather continues with breezy northerly wind Friday
into the weekend.

&&

.AVIATION...

Upr rdg ovhd with VFR conds for Intr NorCal nxt 24 hrs exc lcl
MVFR poss vcnty of Delta in ST til 18z this mrng. Isold MVFR poss
in FU vcnty of wildfires nr Clear Lake, Red Bluff, and NE
Foothills of Sacramento Valley. Lcl Nly sfc wnd gsts in Cntrl Vly
to 20 kts poss tda, then lcl Sly to 25 kts tngt. In Delta, areas
SW sfc wnd up to 25 kts with gusts up to 35 kts this aftn and
tngt.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM PDT this evening for Central Sacramento
Valley-Clear Lake/Southern Lake County-Motherlode-Mountains
Southwestern Shasta County to Northern Lake County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Western Plumas County/Lassen Park.

Red Flag Warning until 8 PM PDT this evening for Carquinez
Strait and Delta-Central Sacramento Valley in Glenn, Colusa,
Yuba, Northern Sutter, and Butte County Below 1000 Ft-Eastern
Mendocino NF-Eastern Portion of Shasta/Trinity NF-Lake County
Portion of Lake-Napa-Sonoma Unit-Northern Motherlode From 1000
to 3000 Ft. Includes portions of Nevada-Yuba-Placer-Amador and
ElDorado Units-Northern Sacramento Valley to Southern Tehama
County Line Below 1000 Ft-Northern San Joaquin Valley in San
Joaquin and Stanislaus Counties Below 1000 ft-Northern Sierra
Foothills from 1000 to 3000 Ft. Includes portions of Shasta-
Trinity and Butte Units-Southeast Edge Shasta-Trinity NF and
Western Portions of Tehama-Glenn Unit-Southern Motherlode From
1000 to 3000 Ft. Includes portions of Calaveras-Tuolumne Unit-
Southern Sacramento Valley in Yolo-Sacramento Far Western
Placer, southern Sutter and Solano County Below 1000 Ft.

&&

$$