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269
FXUS66 KSTO 230817
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
117 AM PDT Sun Jun 23 2024

.SYNOPSIS...
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Slight cooling trend begins today and through the week, with mostly
dry weather expected. Temperatures are expected to reach near normal
by the end of the week, though there is a potential for a new
warming trend next weekend.
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&&

Key Points
- Widespread Moderate HeatRisk is expected today.
- Decreasing areas of Moderate HeatRisk remain in the Valley Monday
  through Wednesday.
- Temperatures cool to near normal by the end of the week, with a
  new warming trend possible late in the weekend.

Short-Term Discussion (Today THROUGH Wednesday)...
The Heat Advisory that was in place today has expired as of 8PM
this evening. Overnight temperatures remain quite warm tonight,
with the midnight measurements around the Valley and foothills
ranging from the high 70s to mid 80s. Conditions will continue to
cool a bit, but will remain in the mid 60s to mid 70s in most of
these Valley and foothill locations. On Sunday, a slight cooling
trend begins as the ridge bringing the hot temperatures today
moves further east. Daytime highs will be cooler by a few degrees,
though widespread Moderate HeatRisk remains throughout interior
NorCal on Sunday.

As a trough moves in over the CONUS from the Pacific, the cooling
trend continues in our area, and HeatRisk begins to recede to
mostly Minor risk, with diminishing areas of Moderate expected
until Wednesday. High temperatures will range in the Valley
between the 90s and very low 100s, and in the foothills and
mountains in the 80s and 70s respectively. Accompanying and
assisting this gradual decline in temperatures will be onshore
flow, with occasionally gusty south to west winds late in the day.
Conditions will generally remain dry throughout this period,
though on Tuesday ensemble members have some agreement that
there is a slight chance (10-15% probabilities) for isolated
thunderstorms in the mountains, primarily south of I-80. Any
storms that develop will quickly move east off the Sierra crest,
but will be capable of producing brief heavy rain, gusty winds,
and lightning while in our area.

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.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...
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Thursday and Friday see only widespread Minor HeatRisk, as the
troughing pattern begins to move across CONUS in earnest. High
temperatures will continue to trend down and end up reaching near
normal levels for the time of year. Highs will be in the 90s in
the Valley, 80s in the foothills, and 70s in the mountains. There
is still some uncertainty over what the upper levels will do over
the weekend, though confidence is growing that westerly flow will
develop at some point, and most ensembles and clusters are showing
growing heights on Sunday. If this holds, it generally means that
Saturday`s high temperatures will remain closer to normal before
a warming trend begins again on Sunday. Otherwise, dry and calm
weather continues throughout the extended period.
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&&

.AVIATION...
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VFR conditions next 24 hours. Surface wind gusts generally below
12 kts except local south to west gusts 15-20 kts 20Z thru about
02Z Monday. Local southwest gusts 15-25 kts vicinity west Delta.
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.STO WATCHES/WARNINGS/ADVISORIES...
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None.
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&&

$$