032
FXUS66 KSTO 100851
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
151 AM PDT Mon Jun 10 2024

.SYNOPSIS...
A significant heat-up is expected early this week. Major HeatRisk
and widespread 100s will develop across the foothills and Valley
by Tuesday and continuing into Wednesday. Temperatures will trend
cooler late in the week.

&&

.DISCUSSION...

Key Points

- An Excessive Heat Warning for areas north of I-80 remains in
  effect from Tuesday morning through Wednesday evening with areas
  of Major HeatRisk and widespread triple digit highs Tuesday
  afternoon.
- A Heat Advisory for areas south of I-80 is in effect from
  Tuesday morning though Wednesday evening with widespread
  Moderate HeatRisk and areas of Major HeatRisk.
- Local waterways are still running cold and fast from snowmelt

Short-Term Discussion (Today THROUGH Thursday)...

Onshore flow is bringing temperatures slightly cooler this
morning. The pattern will transition into more zonal and weak
northerly flow as a upper level high pressure sets up in the
Eastern Pacific. Highs will rise 5-10 degrees for afternoon highs
with areas of the Northern Sacramento Valley reaching triple
digits. This will bring widespread Moderate HeatRisk with areas
of Major HeatRisk in the northern and central Sacramento Valley
and northern San Joaquin Valley. The NBM continues to show Valley
highs in the mid to upper 90s south of Interstate 80, with 100-104
to the north.

The heat peaks on Tuesday, with Valley highs forecast 100-107,
warmest over the northern Sacramento Valley. There will be
widespread Major HeatRisk in the foothills and much of the Valley,
though a very weak Delta flow could mitigate this to some extent
for the Delta Area into the Southern Sacramento Valley. This
effect will be most notable on Wednesday, when the Delta breeze
is projected to lower highs as much as 5-10 degrees for the Delta
and southern Sacramento Valley. The rest of the area should remain
about as hot as Tuesday.

An Excessive Heat Warning remains in effect for areas north of
I-80 from Tuesday morning through Wednesday evening with areas of
Major HeatRisk and widespread triple digit highs by Tuesday. A
Heat Advisory remains in effect for areas south of I-80 from
Tuesday morning though Wednesday evening with widespread Moderate
HeatRisk and areas of Major HeatRisk. Afternoon highs range from
95 to 103, hottest on Tuesday. The Delta breeze should bring some
noticeable cooling the southern Sacramento Valley and Delta
regions by Wednesday evening. Thursday morning the Delta and
Sacramento metro area should see lows in the mid 50s to low 60s.
Thursday highs will be cooler as well there, near normal levels in
the 80s to near 90. Warmer overnight lows will continue across
the northeastern foothills and northern Sacramento Valley,
although still trending a few degrees cooler.

Be sure to check on vulnerable friends, family and neighbors
during this heat event and reconsider outdoor activities during
the hottest parts of the day!

To view the latest HeatRisk, please visit
www.wpc.ncep.noaa.gov/heatrisk/

Area waterways continue to run fast and cold from snowmelt,
creating dangerous conditions for those seeking relief in rivers
and lakes.

To view current water temperatures, please visit
www.cnrfc.noaa.gov

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)...

Deep upper low in the GOA Friday progged through the PacNW over
the weekend with associated upper troughing moving through NorCal.
Longwave trough remains along the W Coast into early next week as
additional short waves track through the PacNW. Resultant broad
upper troughing and increased onshore flow will provide some
synoptic cooling over the extended period, but high temperatures
expected to remain above normal. Dry weather forecast with highs
in the 90s for the Central Valley with 70s and 80s for the
mountains and foothills.

&&

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

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 11 AM Tuesday to 8 PM PDT Wednesday
for Central Sacramento Valley-Mountains Southwestern Shasta
County to Western Colusa County-Northeast Foothills/Sacramento
Valley-Northern Sacramento Valley-Shasta Lake Area / Northern
Shasta County.

Heat Advisory from 11 AM Tuesday to 8 PM PDT Wednesday for
Carquinez Strait and Delta-Motherlode-Northern San Joaquin
Valley-Southern Sacramento Valley.

&&

$$