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917
FXUS66 KSTO 192128
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
228 PM PDT Wed Jun 19 2024


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

Key Points
- Generally seasonable temperatures continue through Thursday,
  much warmer Friday into the weekend, hottest on Saturday.
- Widespread Moderate HeatRisk is expected from Friday through
  Sunday
-A Heat Advisory is in effect from 11 am to 8 pm Saturday with
 Widespread Moderate HeatRisk and areas of Major HeatRisk in the
 Valley and foothills on Saturday; Highs in the triple digits.

Short-Term Discussion (Today THROUGH Saturday)...
Ensembles and clusters indicate that weak upper level trough will
remain over NorCal through Thursday. This trough will weaken and
gradually transition into a ridge during the weekend, as an upper
high strengthens over the Desert Southwest. This will have
temperatures warming to slightly above normal Thursday in the
90`s, before heating up to well above normal levels from the upper
90`s to low 100`s Friday. Widespread triple digit heat is expected
Saturday with Valley and lower foothill highs 100-106.

Widespread Moderate HeatRisk is expected to start Friday and will
continue through the weekend, with areas of Major HeatRisk on
Saturday. Currently probabilities of Sacramento Valley locations
(north of Sacramento metropolitan area) reaching at least 100
degrees on Friday are 50 to 90%, on Saturday 75 to 95%. From the
Sacramento metropolitan area and southward into the northern San
Joaquin Valley, chances are 15 to 50% probability Friday, 75 to
85% on Saturday.

Outside of the Delta, winds will generally be light, helping to
reduce critical fire weather conditions a bit, despite lowering
relative humidity Friday and especially Saturday.

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...
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Temperatures on Sunday trend a little less hot as an upper level
low flattens the ridge, with HeatRisk mainly in the Moderate
level. Valley highs are forecast to be in the upper 90s to low
100s. The desert Southwest high pressure ridge shifts east ward
early next week as a short wave moves through, with temperatures
trending a little lower. The short wave trough exits east
Wednesday, allowing high temperatures to warm back up 2 to 4
degrees.
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&&

.AVIATION...
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VFR conditions expected over the next 24 hours across Northern
California. Winds will remain below 12 kts, except for the
Sacramento sites (SMF, SAC, MHR, MCC) where gusts 15-20 kts are
possible between 00z-05z Thursday.
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&&

.STO WATCHES/WARNINGS/ADVISORIES...
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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.
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&&

$$