411
FXUS66 KSTO 280930
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
230 AM PDT Fri Jun 28 2024

.SYNOPSIS...
Modest warming and periodically breezy weather through the
weekend. Confidence is high in hot weather with widespread Major
to Extreme HeatRisk next week. Breezy north winds and low
humidity will bring fire weather concerns to the Sacramento Valley
early next week.

&&

Key Points
- Likely a major heat event next week impacting holiday outdoor
  events.
- Elevated to critical fire weather conditions Monday thru
  Wednesday.

.Discussion...
Modest warming trend expected through the weekend as the upper
trough weakens over NorCal allowing high temperatures in the
valley to inch back toward the century mark. Marine layer remains
shallow (less than 1k ft deep), but enough to bring some local
breezes and overnight cooling to the Delta and southern Sacramento
Valley.

Strong short-wave forecast to clip far northern California on
Sunday may bring a few thunderstorms along the Oregon border and
over northeast California, but likely remain north of the STO
forecast area.

Next week`s heat wave kicks off on Monday as ensembles continue to
show strong ridging building into NorCal from the eastern Pacific.
Highs Monday will mostly be in the 100 to 105 range across the
Central Valley with areas of breezy north wind and low humidity
expected to result in elevated to critical fire weather conditions
across portions of the Sacramento Valley.

&&

.EXTENDED DISCUSSION (Tuesday THROUGH Friday)...
Significant heat wave projected through the extended period with
the potential for records to be broken. Strong upper high in EPAC
is modeled to progress towards the West Coast through next week
with a 598-600 DM high centered over CA by next Friday. 850 mb
temps progged to rise from the upper 20s Deg C Tuesday into the
lower 30s Deg C Thursday into Friday. Triple digit heat will
result in the Central Valley and portions of the foothills through
the week. Max temps at or above 110 deg F possible in the
northern half of the Sacramento Valley Wednesday could become more
widespread through much of the Central Valley Thurs/Fri. Little
relief expected overnight with 70s to 80s in portions of the
Central Valley and foothills. Areas of gusty northerly wind
Tuesday into Wednesday in the Central Valley and adjacent
foothills could result in periods of critical fire weather
conditions.

&&

.AVIATION...
VFR conditions over interior NorCal next 24 hrs. Sfc wind mainly
below 12 kts except vcnty of Delta aft 23z Fri SWly sfc wind up to
20 kts.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Tuesday morning through Friday evening
for Central Sacramento Valley-Motherlode-Mountains Southwestern
Shasta County to Western Colusa County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley.

&&

$$