366
FXUS66 KSTO 141954
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1254 PM PDT SUN SEP 14 2025
DISCUSSION
SYNOPSIS
SEASONABLE TEMPERATURES AND DRIER WEATHER TODAY. WARMING AND
DRYING TREND TO ABOVE NORMAL TEMPERATURES WITH PERIODICALLY BREEZY
NORTHERLY WINDS EARLY TO MID WEEK. RETURN OF SHOWER AND
THUNDERSTORM CHANCES TO INTERIOR NORCAL LATE-WEEK.
KEY MESSAGES
* TODAY:
- PROGRESSIVE SHORTWAVE TROUGH MOVES ACROSS THE PACIFIC NORTHWEST
- HIGH TEMPERATURES IN THE 80S TO AROUND 90 EXPECTED AT LOWER
ELEVATIONS, WITH 70S TO LOW 80S AT HIGHER ELEVATIONS
* MONDAY - WEDNESDAY:
- THE SHORTWAVE TROUGH SHIFTS EASTWARD EARLY MONDAY, FOLLOWED
RAPIDLY BY AMPLIFYING RIDGING, ALLOWING FOR DRIER AND WARMER
WEATHER EARLY TO MID WEEK
- INCREASING NORTH TO EAST FLOW EXPECTED EARLY MONDAY BEHIND THE
PASSAGE OF THE SHORTWAVE, STRONGEST ALONG AND WEST OF
INTERSTATE 5, AND IN THE MOUNTAIN AND FOOTHILL GAPS/CANYONS
WITH GUSTS TO 15 TO 20 MPH
- LOWERING RELATIVE HUMIDITY, IN THE UPPER TEENS TO UPPER 20S
FOR THE AFTERNOON MINIMUM RH EACH DAY
- WARMING TREND TO ABOVE NORMAL TEMPERATURES WITH VALLEY HIGHS IN
THE 90S
- AREAS OF MODERATE HEATRISK TUESDAY-WEDNESDAY IN THE SOUTHERN
SACRAMENTO VALLEY, DELTA, NORTHERN SAN JOAQUIN VALLEY AND
ADJACENT FOOTHILLS
* LATE WEEK - NEXT WEEKEND:
- CONFIDENCE GRADUALLY INCREASING IN PATTERN CHANGE BRINGING
SHOWER AND THUNDERSTORM CHANCES BACK TO THE FORECAST FOR THE
REGION LATER THIS WEEK AND INTO NEXT WEEKEND, ALTHOUGH
UNCERTAINTY IS STILL HIGH IN EXACT DETAILS ON TIMING, LOCATION,
AND IMPACTS
- SLIGHTLY COOLER TEMPERATURES AND HIGHER RELATIVE HUMIDITY
CHANGES FROM PREVIOUS FORECAST
-SHOWER AND THUNDERSTORM CHANCES HAVE INCREASED SLIGHTLY FOR
THURSDAY THROUGH SATURDAY
AVIATION
VFR CONDITIONS EXPECTED AT INTERIOR NORCAL TAF SITES NEXT 24
HOURS AND LIGHT WINDS LESS THAN 12 KTS UNTIL 09Z MONDAY BEFORE
INCREASING NORTH VALLEY WINDS 10 TO 15 KTS DEVELOP, STRONGEST
ALONG THE WESTERN PORTIONS THE VALLEY AND DELTA. CURRENT FORECAST
SHOWS THE A 15-30% CHANCE OF STRATUS IN THE VALLEY SOUTH OF I-80
FROM 13Z TO 16Z MONDAY.
STO WATCHES/WARNINGS/ADVISORIES
NONE.
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