294
FXUS66 KSTO 201930
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1230 PM PDT MON JUL 20 2026
FOR ADDITIONAL DETAILS ON WEATHER AND EXPECTED IMPACTS OVER THE
NEXT 7 DAYS, PLEASE VISIT WEATHER.GOV/STO/BRIEFING.
KEY MESSAGES
- MONSOONAL AND SUBTROPICAL MOISTURE PUSHING THROUGH THE AREA
NEXT FEW DAYS, MAINLY BRINGING SPRINKLES OR A STRAY SHOWER TO
VALLEY; SLIGHT CHANCES FOR HIGHER ELEVATION THUNDERSTORMS.
- SEASONABLE HIGH TEMPERATURES CONTINUE, MINOR HEATRISK WITH
AREAS OF MODERATE HEATRISK THROUGH WEDNESDAY, THEN WIDESPREAD
MINOR HEATRISK INTO THE WEEKEND.
- ELEVATED FIRE WEATHER CONDITIONS DUE TO DRY/WET THUNDERSTORMS
CHANCES IN THE HIGHER ELEVATIONS TODAY THROUGH WEDNESDAY.
DISCUSSION
MID-LEVEL TO HIGH CLOUDS PASSING THROUGH THE AREA THIS AFTERNOON,
AS SUBTROPICAL MOISTURE IS PUSHING TOWARDS CALIFORNIA FROM POST-TROPICAL
CYCLONE ELIDA. A FEW SPRINKLES/LIGHT SHOWERS HAVE BEEN OBSERVED AT
LOWER ELEVATIONS THROUGH THE MORNING, HOWEVER NOTHING SIGNIFICANT
HAS REACHED THE GROUND. WE WILL CONTINUE TO HAVE SCATTERED CLOUD
COVERAGE IN THE VALLEY THROUGHOUT THE REST OF THE DAY, WHILE IN
THE SIERRA MONSOONAL MOISTURE ASSOCIATED WITH A HIGH PRESSURE IN
THE ROCKIES MOVES IN. WHILE THE NBM HAS ROUGHLY 10-20% CHANCES FOR
AN AFTERNOON SHOWER OR DRY/WET THUNDERSTORM THIS AFTERNOON,
PRIMARY LIMITING FACTOR WILL ONCE AGAIN BE THE LACK OF
INSTABILITY. FORECAST SOUNDINGS IN HIGHER ELEVATIONS DO NOT REVEAL
MUCH IN THE FORM OF MUCAPE OR ELEVATED INSTABILITY IN OUR CWA.
BETTER INSTABILITY AND VORTICITY/FORCING WILL RESIDE ALONG AND EAST
OF THE SIERRA CREST.
SIMILAR CONDITIONS EXPECTED TOMORROW HOWEVER BETTER THUNDERSTORM
CHANCES IN THE SIERRA ARE EXPECTED. SLIGHTLY STRONGER PUSH OF
MONSOONAL MOISTURE COUPLED WITH RIDGE-RIDING SHORTWAVES MAY HELP
PROVIDE ADDITIONAL INSTABILITY TO PRODUCE THUNDERSTORMS IN THE
AFTERNOON AND EVENING HOURS. AS SUCH, WITH THE THREAT OF LIGHTNING
FROM ANY STORM THAT DEVELOPS, ELEVATED FIRE WEATHER CONDITIONS
WILL CONTINUE THROUGH WEDNESDAY MAINLY FROM THE RISK OF NEW FIRE
STARTS FROM LIGHTNING OUTSIDE OF RAIN CORES. OUR PRECIPITATION
CHANCES WILL BEGIN TO BACK OFF THURSDAY AS OFF SHORE TROUGHING
TAKES OVER THE SYNOPTIC SETUP AND THE RIDGE IN THE ROCKIES BEGINS
TO DIG FURTHER SOUTH INTO THE FOUR CORNERS REGION WITH DRIER AIR
EMBEDDED LIMITING CONVECTION POTENTIAL FOR OUR CWA.
TEMPERATURE WISE, WE CONTINUE TO BE MOSTLY SEASONABLE FOR THE NEXT
FEW DAYS, WITH MOSTLY MINOR HEATRISK AND AREAS OF MODERATE
HEATRISK IN THE VALLEY. WARMEST DAY IN THE SHORT-TERM FORECAST
IS WEDNESDAY, WHERE TRIPLE-DIGIT HEAT IS EXPECTED IN THE NORTHERN
SACRAMENTO VALLEY AND MID TO UPPER 90S FOR THE REST OF THE
VALLEY. "COOLER" TEMPERATURES THURSDAY AND FRIDAY, THEN A RETURN
TO MID 90S AND TRIPLE-DIGITS EXPECTED.
AVIATION
VFR CONDITIONS NEXT 24 HOURS ACROSS INTERIOR NORCAL TAF SITES.
SCT TO BKN CLOUDS ACROSS THE DELTA AND SACRAMENTO AREAS. SURFACE
WINDS BELOW 12 KNOTS EXCEPT IN DELTA VICINITY WHERE GUSTS OF 25 TO
30 KNOTS POSSIBLE THROUGH AROUND 06Z TUESDAY. SLIGHT THUNDERSTORM
CHANCES IN HIGHER ELEVATIONS FROM 20Z THROUGH 07Z.
STO WATCHES/WARNINGS/ADVISORIES
NONE.
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