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840
FXUS66 KSTO 210800
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
100 AM PDT Fri Jun 21 2024

.SYNOPSIS...
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Dry weather continues, with a warming trend into the weekend.
Temperatures peak on Saturday, with widespread triple digit highs
in the Central Valley and into the lower foothills. A little less
hot early next week.
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&&

Key Points:
- Widespread Moderate HeatRisk is expected today through Monday,
  with areas of Major HeatRisk today-Saturday
- A Heat Advisory is in effect from 11 am to 8 pm Saturday with
  Widespread Moderate HeatRisk and areas of Major HeatRisk in the
  Central Valley and foothills on Saturday; Highs in the triple
  digits.

Short-Term Discussion (Today THROUGH Monday)...
Ensembles and clusters indicate that the transition to upper
level ridge will begin over NorCal today. The ridge will amplify
over the weekend, as an upper high strengthens over the Desert
Southwest. This will cause temperatures to heat up to well above
normal levels from the upper 90`s to low 100`s today. Widespread
triple digit heat is expected Saturday with Central Valley and
lower foothill highs 100-106. Some Delta air will modify the late
afternoon high temperatures over the Delta, and portions of the
southern Sacramento Valley keeping most of these areas in moderate
heat risk versus major to the north and over the foothills.
Increasing southwest flow is expected over NorCal Sunday, as a
trough moves through the Pacific Northwest. This will likely
initiate an afternoon Delta breeze with high temps a few degrees
cooler in the upper 90`s and low 100`s.

Widespread Moderate HeatRisk expected through Monday, with areas
of Major HeatRisk today and Saturday mainly over the Sierra
foothills & northern Sacramento Valley. The National Blend of
Models (NBM) is indicating a 80-100% chance of temperatures
greater than 100 degrees F throughout most of the Valley on
Saturday.

By Sunday, a trough is expected to move through the Pacific
Northwest resulting in increased southwesterly flow. This will
translate into a more robust Delta breeze on Sunday with gusts
15-25 mph through the Valley. Slightly cooler temperatures will
follow, but Moderate HeatRisk is expected to continue across most
of the Central Valley and foothills through Monday.

&&

.EXTENDED DISCUSSION (Tuesday THROUGH Friday)...
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Interior NorCal sandwiched between Desert SW high and short wave
trough to the NW Tuesday into Wednesday. High temperatures in the
Central Valley expected from the upper 90s to around 102, hottest
in the Northern Sacramento Valley. Cooling around 2 to 5 degrees
Thursday into Friday as short wave trough pushes into the PacNW
and heights lower over the CWA.
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&&

.AVIATION...
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VFR conditions over interior NorCal next 24 hrs exc lcl MVFR/IFR
possible in ST vcnty of Delta til 17z. Sfc wind mainly below 12
kts except vcnty of Delta SWly sfc wind 15-25 kts.
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&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM to 8 PM PDT Saturday for Central
Sacramento Valley-Motherlode-Mountains Southwestern Shasta
County to Western Colusa County-Northern Sacramento Valley-
Northern San Joaquin Valley-Southern Sacramento Valley.

&&

$$