-- Discussion containing changed information from previous version are highlighted. --
398
FXUS66 KSTO 102109
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
209 PM 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...

-- Changed 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)...
Very little changes to the forecast as ensembles still on track.

Tonight and Tuesday...as has been exptected for a while with both
GFS and ECMWF Ensembles....some riding builds into northern
California tonight between deep upper low in Gulf of Alaska and a
weak closed upper low off coast of southern California. Major
HeatRisk values covering most of northern california with slightly
lower values south of I80 and the current highlights look good.

Wednesday heights start to fall as we get more under the influence
of the Gulf of Alaska low pressure system. This will bring good
onshore flow wednesday afternoon and keep temperatures down a bit
south of I80. We may be able to expire the Heat Advisory south of
I80 but will keep it out for now.

Ensembles and clusters in good agreement that we will get more
westerly flow and lower heights and HeatRisk values fall to
moderate most area.

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
-- End Changed Discussion --

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)...
-- Changed Discussion --
Friday into the weekend the large Gulf of Alaska low will
continue to impact the area. This will result in cooler
temperatures and possibly some wind starting to work into the
forecast...especially north and west parts of the valley. This may
result in some elevated fire conditions which we will look closer
at tomorrow as confidence increases for possibly messaging. Rasch
-- End Changed Discussion --

&&

.AVIATION...
-- Changed Discussion --
VFR conditions over interior NorCal for the next 24 hrs. Surface
winds mainly below 12 kts except in the vicinity of the Delta
which could have southwesterly wind up to 20 kts at times tonight.
-- End Changed Discussion --

&&

.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.

&&

$$