011
FXUS66 KSTO 131948
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1248 PM PDT WED AUG 13 2025
DISCUSSION
SYNOPSIS
OUTSIDE OF WARMER WEATHER ON FRIDAY, NEAR TO BELOW NORMAL
TEMPERATURES EXPECTED FOR MOST OF THE NEXT SEVERAL DAYS WITH
MAINLY MINOR HEATRISK. PERIODICALLY BREEZY ONSHORE FLOW WILL
ASSIST WITH COOLING AND HIGHER RELATIVE HUMIDITY. SLIGHT CHANCE OF
THUNDERSTORMS MAINLY OVER SHASTA COUNTY VICINITY THIS WEEKEND,
OTHERWISE DRY CONDITIONS PREVAIL.
KEY MESSAGES
*TODAY:
- COOLER TODAY WITH HIGH TEMPERATURES IN THE 80S TO 90S AS UPPER
LEVEL RIDGE WEAKENS
- INCREASED ONSHORE FLOW WILL BRING GUSTS OF 15-25 MPH LATER THIS
AFTERNOON AND EVENING IN THE DELTA VICINITY WHICH WILL BRING
ADDITIONAL COOLING OVERNIGHT
*THURSDAY-FRIDAY:
- SLIGHT WARMING TREND THURSDAY AND FRIDAY WITH DRY CONDITIONS
- AFTERNOON HIGHS THE 90S TO NEAR 100 LATER THIS WEEK FOR MUCH
OF THE VALLEY AND FOOTHILLS
- WIDESPREAD MINOR HEATRISK WITH LOCALIZED MODERATE HEATRISK
*WEEKEND:
- COOLDOWN TO NEAR TO BELOW AVERAGE TEMPERATURES OVER THE
WEEKEND WITH RISING RELATIVE HUMIDITY
- PERIODICALLY BREEZY ONSHORE FLOW IS FORECAST AT TIMES,
STRONGEST IN THE DELTA VICINITY AND OVER THE SIERRA CREST
- 15-25% CHANCE OF ISOLATED THUNDERSTORMS IN SHASTA COUNTY
(INCLUDES NORTHERN SACRAMENTO VALLEY), NORTHERN COAST RANGE,
AND SOUTHERN CASCADES, DRY WEATHER ELSEWHERE
*EARLY TO MID NEXT WEEK:
- BELOW NORMAL TEMPERATURES ON MONDAY WILL GRADUALLY WARM THROUGH
NEXT WEEK AS HIGH PRESSURE IS FAVORED TO BUILD BACK IN OVER
THE WESTERN US, CENTERED OVER THE FOUR CORNERS REGION
CHANGES FROM PREVIOUS FORECAST
- SLIGHT INCREASE IN THUNDERSTORM POTENTIAL FOR THIS WEEKEND OVER
SHASTA COUNTY VICINITY
AVIATION
VFR CONDITIONS WILL CONTINUE FOR THE NEXT 24 HOURS ACROSS
INTERIOR NORCAL. SURFACE WINDS GENERALLY BELOW 12 KNOTS, EXCEPT
FROM AROUND 21Z TODAY THROUGH 13Z THURSDAY, WHERE WEST-SOUTHWEST
GUSTS UP TO 30 KNOTS ARE POSSIBLE AT SOUTHERN/CENTRAL SACRAMENTO
VALLEY AND DELTA SITES. SOUTHERLY SURFACE GUSTS UP TO 25 KNOTS IN
THE NORTHERN SACRAMENTO VALLEY FROM AROUND 20Z UNTIL 06Z THURSDAY.
STO WATCHES/WARNINGS/ADVISORIES
NONE.
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