812
FXUS66 KSTO 071919
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1219 PM PDT MON SEP 7 2026
FOR ADDITIONAL DETAILS ON WEATHER AND EXPECTED IMPACTS OVER THE
NEXT 7 DAYS, PLEASE VISIT WEATHER.GOV/STO/BRIEFING.
KEY MESSAGES
- DRYING AND WARMING TREND THROUGH THURSDAY, WITH AREAS OF
MODERATE TO MAJOR HEATRISK WEDNESDAY AND THURSDAY.
- HEAT ADVISORY IS IN EFFECT 10 AM WEDNESDAY - 10 PM THURSDAY
FOR THE DELTA, VALLEY, AND FOOTHILLS.
- COOLING TEMPERATURES AND BREEZY ONSHORE WINDS FRIDAY INTO THE
WEEKEND.
DISCUSSION
TODAY-THURSDAY:
WHILE TROUGHING ALOFT OVER THE PACNW REMAINS THE PRIMARY DRIVING
FEATURE OF THE WEATHER PATTERN TODAY, RIDGING ALOFT IS BEGINNING
TO BUILD WESTWARD FROM THE DESERT SOUTHWEST. AS THE BUILDING RIDGE
AND INCREASING HEIGHTS ALOFT PUSH TOWARD INTERIOR NORCAL THROUGH
THE MIDDLE OF THE WEEK, ABOVE NORMAL TEMPERATURES AND AREAS OF
MODERATE TO MAJOR HEATRISK LOOK TO BRIEFLY RETURN TO THE REGION.
HIGH TEMPERATURES IN THE UPPER 90S TO LOWER TRIPLE DIGITS
ACCOMPANIED BY WARM OVERNIGHT TEMPERATURES IN THE MID 60S TO 70S
ARE ANTICIPATED ACROSS MUCH OF THE DELTA, VALLEY, AND FOOTHILLS ON
WEDNESDAY AND THURSDAY. AS A RESULT, A HEAT ADVISORY IS IN EFFECT
FROM 10 AM PDT WEDNESDAY - 10 PM PDT THURSDAY FOR THESE
LOCATIONS. ACCOMPANYING THIS WARM UP WILL BE PERIODICALLY BREEZY
AND DRYING NORTH TO EAST WINDS, WITH DAYTIME HUMIDITY INTO THE
TEENS AND POOR TO LIMITED OVERNIGHT HUMIDITY RECOVERY. RESULTANT
ELEVATED FIRE WEATHER CONDITIONS ARE EXPECTED THROUGH THURSDAY.
FRIDAY INTO THE WEEKEND...
RIDGING AND HIGH HEIGHTS ALOFT WILL BEGIN RELAXING BY LATE
THURSDAY AS A LONGWAVE TROUGH STARTS TO DROP DOWN FROM INTERIOR
BRITISH COLUMBIA. THIS IS EXPECTED TO LEAD TO AN ABRUPT COOL DOWN
TO MORE SEASONABLE HIGH TEMPERATURES BY FRIDAY WITH A TREND TOWARD
SLIGHTLY BELOW NORMAL TEMPERATURES THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK. BREEZY ONSHORE WINDS LOOK TO RETURN AS WELL WITH
THE PATTERN SHIFT INTRODUCING SOME IMPROVEMENTS TO DAYTIME
HUMIDITY AND OVERNIGHT RECOVERIES. THERE IS THEN SOME UNCERTAINTY
REGARDING THE EVENTUAL TRACK OF THE TROUGH AS IT EJECTS OUT OF
BRITISH COLUMBIA LATE WEEKEND AND INTO EARLY NEXT WEEK. WHILE
PRECIPITATION IMPACTS ARE GENERALLY NOT ANTICIPATED GIVEN THE DRY
NATURE OF THE SYSTEM AND ANTECEDENT AIR MASS, THERE IS POTENTIAL
FOR BREEZY TO GUSTY NORTH WINDS TO DEVELOP ACROSS INTERIOR NORCAL
DEPENDENT ON THE TROUGH TRAJECTORY.
AVIATION
VFR CONDITIONS PREVAIL AT TAF SITES ACROSS THE FORECAST PERIOD.
BREEZY NORTH TO EAST WINDS ARE EXPECTED AT TIMES, ALTHOUGH
REMAINING 12 KTS OR LESS, WITH STRONGEST WINDS THROUGH THE VALLEY
AND DELTA IN THE LATE MORNING AND AFTERNOON HOURS.
STO WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY FROM 10 AM WEDNESDAY TO 10 PM PDT THURSDAY FOR
BUTTE COUNTY BELOW 1000 FT-C. SAN JOAQUIN COUNTY INCLUDING
STOCKTON-C. SOLANO COUNTY INCLUDING FAIRFIELD-C. STANISLAUS
COUNTY INCLUDING MODESTO-C. YOLO/NE SOLANO INCLUDING WOODLAND-
CENTRAL COLUSA COUNTY INCL. I-5-CENTRAL GLENN CO & INTERSTATE 5-
CENTRAL MOTHERLODE 1000-3000 FT-E. DIABLO RANGE ABOVE 1000 FT-
EASTERN COLUSA COUNTY-EASTERN GLENN COUNTY-N. MOTHERLODE 1000-
3000 FT-N. SAC VALLEY IN TEHAMA COUNTY-NE SAN JOAQUIN VALLEY
BELOW 1000 FT-SW SOLANO COUNTY INCLUDING VALLEJO-SAC METRO/W. EL
DORADO/AMADOR COUNTY-SACRAMENTO COUNTY DELTA-SAN JOAQUIN COUNTY
DELTA-SIERRA (TEHAMA-PLUMAS) 1000-3000 FT-SOUTHERN MOTHERLODE
1000-3000 FT-SUTTER/YUBA COUNTIES BELOW 1000 FT-TRACY TRIANGLE
BELOW 1000 FT-W. STANISLAUS COUNTY ABOVE 1000 FT & I-5-W. YOLO
COUNTY INCLUDING CAPAY/I-505-YOLO / SOLANO COUNTY HILLS.
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