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292
FXUS66 KSTO 242145
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
245 PM PDT Mon Jun 24 2024


.SYNOPSIS...
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Seasonably warm and periodically breezy weather persists across the
early week period, with a slight cooling trend to near normal from
mid to late week and into the weekend. Slight chance of isolated
thunderstorms through Tuesday evening.
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&&

Key Points
- Decreasing Moderate HeatRisk today and Tuesday, and then
  primarily Minor HeatRisk mid-week into the weekend.
- Slight chance of isolated thunderstorms through Tuesday evening,
  best chances over the Sierra Crest south of Highway 50.
- Potential for another warming trend late in the weekend and
  into next week.

Short-Term Discussion (Today THROUGH Thursday)...
Current GOES-West visible satellite imagery shows a band of mid
level moisture creeping northward from the south, as well as some
cumulus clouds developing over the northern Sierra Crest this
afternoon. Temperatures are currently trending approximately 1 to
6 degrees cooler than this time yesterday afternoon across
interior northern California, valid at 230 PM PDT. Moderate
HeatRisk continues today for much of the Valley and foothills, as
seasonably warm temperatures prevail and high pressure continues
across the Desert Southwest. An area of low pressure will approach
the Pacific Northwest over the next several days, bringing some
cooling to the area, back to around normal for this time of year,
and HeatRisk down to around Minor for the rest of this week.

There is some monsoonal moisture moving into the area today and
Tuesday that we will be keeping an eye on. The best chances for
thunderstorm development would be over the Sierra Crest south of
Highway 50, where there is a 10-15% probability this afternoon,
and a 15-30% probability Tuesday afternoon. Confidence is low, but
there is also potential for a stray thunderstorm in the Valley
and foothills this afternoon and overnight into Tuesday as well.
High resolution models are struggling to capture what is
developing to the south this afternoon, so we have introduced a
slight chance of thunderstorms in the lower elevations through
Tuesday evening to address the nonzero potential for a stray
thunderstorm. Otherwise, mid level clouds and some virga may be
observed over the same timeframe. Potential impacts with any
thunderstorms that develop would be lightning, gusty winds, small
hail, brief heavy rain, and possible fire starts. When thunder
roars, go indoors!

&&


.EXTENDED DISCUSSION (Friday THROUGH Monday)...
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Ensemble guidance and cluster analysis are in general agreement
for mainly westerly flow over the extended forecast period, with
heights increasing later in the weekend and into early next week
as weak ridging starts to develop over the Great Basin area this
weekend, and then stronger ridging developing over the Eastern
Pacific by early next week with a weaker trough in between. As a
result, slightly warmer temperatures are forecast on Sunday, and
into early next week as well, although there is still a spread for
high temperatures over this timeframe. Valley temperatures look
like they will trend from the upper 80s and low to mid 90s on
Friday and Saturday to the high 90s and low 100s by Monday. The
National Blend of Models (NBM) suggests a 30 to 70 percent
probability of reaching or exceeding 100 degrees for the daytime
high in the Valley on Monday.
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&&

.AVIATION...
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VFR conditions expected over the next 24 hours across Northern
California. Surface winds 10-15 kts with gusts up to 20 kts
through 03z Wednesday, southerly through the Sacramento Valley and
northwesterly through the northern San Joaquin. In the Vicinity
Delta, westerly winds 10-15 kts with gusts up to 20 kts thru 14z
Tuesday. Additionally, there is a 10-30% chance of isolated
thunderstorms over the Valley, foothills, & mountains.
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&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.


&&

$$