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290
FXUS66 KSTO 110949
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
249 AM PDT Tue Jun 11 2024

.SYNOPSIS...
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Hot temperatures through Wednesday with Moderate to Major
HeatRisk. Temperatures will trend cooler late in the week and
over the weekend. Isolated shower/thunderstorms over the Sierra
Crest south of Highway 50 this afternoon. Elevated fire weather
conditions this weekend.
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.DISCUSSION...

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Key Points

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

Short-Term Discussion (Today THROUGH Friday)...
Current GOES-West satellite imagery shows generally clear skies
across interior northern California early on this Tuesday
morning. Current temperatures are trending approximately 3 to 10
degrees warmer than this time yesterday morning, valid at 230 AM
PDT. The forecast largely remains on track for hot temperatures
to impact the area today, with forecast highs in the triple
digits for much of the lower elevations. Overnight temperatures
will also be warm, in the 60s to mid 70s for the Valley and
foothills. Moderate to Major HeatRisk has warranted an Excessive
Heat Warning (mainly north of I-80), and a Heat Advisory (mainly
south of I-80) that both remain in effect through Wednesday
evening. The extent of the Delta Breeze influence and increased
onshore flow on Wednesday may allow for part or all of the
advisory (not the warning) to be dropped earlier tomorrow. There
is a 10-20% probability for a shower/thunderstorm over the Sierra
Crest south of Highway 50 this afternoon and evening. Elsewhere,
dry conditions prevail over the next several days.

For later this week, temperatures are expected to trend cooler as
a low pressure area approaches from the Gulf of Alaska. Increased
onshore flow and cooler temperatures are expected from the
influence of the low. In terms of HeatRisk, over the Thursday and
Friday timeframe, mainly Minor HeatRisk prevails across our area
of responsibility, with just some localized Moderate HeatRisk
mainly in the northern/central Sacramento Valley. Forecast highs
in the Valley are projected to be in the 80s to 90s later this
week, which will be cooler than today-Wednesday, but still
trending above normal for mid June climatology. Additionally,
area waterways continue to run fast and cold from snowmelt,
creating dangerous conditions for those seeking relief in rivers
and lakes. Be sure to practice heat and cold water safety this
week!

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

To view current water temperatures, please visit
www.cnrfc.noaa.gov
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.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
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Long wave trough sets up along the West Coast over the weekend
and persists into early next week as several short wave troughs
move through the PacNW. Synoptic cooling with increased onshore
flow expected. High temperatures in the Central Valley projected
in the upper 80s to lower 90s with upper 60s to 80s for the
mountains and foothills. Low level north-south pressure gradient
strengthens over interior NorCal this weekend resulting in some
gusty northerly wind in the Central Valley and elevated fire
weather conditions.
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.AVIATION...
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Generally VFR conditions over interior NorCal next 24 hrs except
possible isolated MVFR in tstm over higher terrain of Alpine and
Tuolumne counties btwn 20z-03z. Sfc wind mainly below 12 kts
except vcnty of Delta aft 00z Wed SWly sfc wind up to 20 kts
possible.
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&&

.STO WATCHES/WARNINGS/ADVISORIES...
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Excessive Heat Warning from 11 AM this morning 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 this morning to 8 PM PDT Wednesday for
Carquinez Strait and Delta-Motherlode-Northern San Joaquin
Valley-Southern Sacramento Valley.
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$$