216
FXUS66 KSGX 170946
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
246 AM PDT SAT OCT 17 2026
SYNOPSIS
SANTA ANA WINDS EXPECTED THROUGH TOMORROW; GRADUALLY WEAKENING BY
LATER THIS EVENING INTO TOMORROW MORNING, WITH THE STRONGEST AND
MOST WIDESPREAD WINDS TODAY. ADDITIONALLY, MODERATE TO MAJOR
HEATRISK IS EXPECTED FOR COASTAL AREAS. COOLER CONDITIONS WILL
SPREAD INLAND TOMORROW, WITH GREATER COOLING, INCREASE IN
WESTERLY WINDS, AND CHANCE OF SHOWERS FOR THE MIDDLE OF NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
TODAY THROUGH TOMORROW NIGHT...
WITH STRONG AND GUSTY WINDS IN PLACE THROUGHOUT THE NIGHT FOR MOST
LOCATIONS, TEMPERATURES HAVE REMAINED RATHER WARM OVERNIGHT, WITH
INCREASING CLOUDS (MOSTLY MID TO HIGH LEVEL) AS AN UPPER LEVEL LOW
ADVANCED TOWARDS THE REGION FROM THE SOUTH. THERE ARE SOME SHOWERS
(AND EVEN A FEW EMBEDDED THUNDERSTORMS) VIEWABLE ON RADAR OVER
NORTHERN BAJA CALIFORNIA, AND THIS MOISTURE WILL PROVIDE THE REGION
WITH A FEW LIGHT TO MODERATE RAIN SHOWERS BEING POSSIBLE, ALTHOUGH
THE LOWER LEVELS ARE SO DRY THAT IF ANYTHING WERE TO FALL, IT WOULD
MOST LIKELY EVAPORATE BEFORE IT REACHES THE GROUND. STILL, IT CANNOT
BE RULED OUT.
SANTA ANA WINDS WILL CONTINUE TODAY AND INTO TOMORROW, BUT GRADUALLY
BEGIN TO WEAKEN AS THE PRESSURE GRADIENT LOOSENS WITH THE U/L LOW
PULLING AWAY BY LATER THIS EVENING AND THE HIGH PRESSURE CENTERED
OVER THE GREAT BASIN WEAKENING AS THE RIDGE BEGINS TO FLATTEN OVER
THE WESTERN CONUS. EXPECT WINDS TO GENERALLY GUST BETWEEN 35 AND 55
MPH FOR THE MOST WIND-PRONED AREAS, WITH LOCAL GUSTS POSSIBLY OVER
60 MPH BELOW PASSES AND ALONG MOUNTAINS SLOPES/FOOTHILLS. THESE
DOWNSLOPING WINDS WILL CONTINUE TO KEEP TEMPERATURES RATHER WARM,
ESPECIALLY FOR THE COASTS, WITH LOW TO MID 90S BEING POSSIBLE. IT
SHOULD BE A COUPLE DEGREES COOLER FOR MOST LOCATIONS THAN YESTERDAY,
ESPECIALLY WITH THE EXTENSIVE CLOUD COVERAGE MOVING IN OVER THE
REGION THIS MORNING DUE TO THE U/L LOW BEING IN THE VICINITY. THESE
WARM TEMPERATURES WILL ALSO LIKELY KEEP TEMPERATURES ELEVATED
OVERNIGHT, WITH RECORD HIGH MINIMUMS MAY OCCUR, WHERE WINDS REMAIN
GUSTY AND MIXING PERSISTS WITHIN THE PBL. THERE WILL BE SOMEWHAT A
DECOUPLING OF THE WINDS FOR TOMORROW NIGHT, AND SOME AREAS MIGHT
HAVE WINDS BECOME CALM ENOUGH FOR THERE TO BE SOME MORE EFFICIENT
COOLING. FOR ALL OTHER LOCATIONS, THE ELEVATED WINDS WILL KEEP
OVERNIGHT LOWS MILD AGAIN FOR TOMORROW NIGHT. ALTHOUGH THERE ARE
STRONG WINDS IN PLACE, RH VALUES HAVE INCREASED A BIT FROM WHERE
THEY WERE A COUPLE OF DAYS AGO, WITH THE VALLEYS DROPPING TO AROUND
20 TO 30 PERCENT MINIMUMS BY LATER THIS AFTERNOON. THIS TRANSLATES
TO FIRE CONCERNS STILL REMAINING ELEVATED THROUGHOUT THE DAY. THERE
WILL ONLY BE A VERY SLIGHT CHANCE OF THERE BEING A FEW SHOWERS THIS
MORNING FOR SAN DIEGO COUNTY, MAINLY OVER THE MOUNTAINS AND DESERTS
OF THE SOUTHEASTERN PORTION OF THE COUNTY. WITH OFFSHORE FLOW
CONTINUING INTO TOMORROW, IT WILL INHIBIT THE MARINE LAYER FOR ONE
MORE NIGHT.
MONDAY THROUGH THURSDAY...
BY SUNDAY EVENING INTO MONDAY MORNING, WINDS WILL GRADUALLY WEAKEN
AND RETURN TO BEING ONSHORE. SOME OF THE HIGH RES MEMBERS ARE
REVEALING SOME LOW LEVEL MOISTURE MOVING BACK INTO THE INNER SOCAL
WATERS, WHICH ALLUDES TO THE POSSIBILITY OF THERE BEING SOME PATCHY
FOG OVER THE COASTAL WATERS, AND ALSO ALONG PORTIONS OF THE COASTAL
AREAS. SOME OF THESE AREAS OF PATCHY FOG MAY ALSO YIELD DENSER FOG
DOWN TO BELOW A QUARTER OF A MILE. THE NOTABLE COOLDOWN WILL BEGIN
ON MONDAY AS A LONGWAVE TROUGH ADVANCES TOWARDS THE REGION. THIS
WILL ALLOW FOR THE ONSHORE FLOW TO STRENGTHEN GOING INTO TUESDAY
MORNING, AND BRING ABOUT THE POSSIBILITY OF MORE PATCHY FOG, WITH
BETTER COVERAGE EXTENDING FURTHER INLAND. TEMPERATURES BY TUESDAY
WILL GENERALLY BE ANYWHERE FROM 5 TO 10 DEGREES BELOW AVERAGE. BY
LATER IN THE EVENING, THERE MAY BE A FEW DEVELOPING SHOWERS WEST OF
THE MOUNTAINS AS AN ASSOCIATED MAJOR SHORTWAVE TROUGH BEGINS TO
PROPAGATE OVER THE REGION GOING INTO WEDNESDAY. THIS WILL ALLOW FOR
WINDS AND RAIN TO BECOME MORE WIDESPREAD OVER THE REGION FROM
WEDNESDAY INTO THURSDAY AS THE AREA OF LOW PRESSURE ALOFT MOVES OVER
THE AREA. THIS WILL KEEP THE COOL AND INCLEMENT WEATHER STICKING
AROUND THROUGH THEN, WITH HIGHS ON BOTH WEDNESDAY AND THURSDAY
RUNNING AROUND 15 TO 20 DEGREES BELOW AVERAGE FOR MOST LOCATIONS.
SNOW LEVELS WILL ALSO DROP DOWN TO AROUND 8000-8500 FT MSL, WITH A
FEW INCHES OF SNOWFALL FOR THE HIGHER TERRAIN ABOVE. PRELIMINARY
RAINFALL AMOUNTS FOR THIS STORM SYSTEM LOOK TO BE AROUND A HALF AN
INCH TO THREE QUARTERS OF AN INCH FOR MOST OF THE COASTAL AND INLAND
AREAS, WITH HIGHER AMOUNTS UP TO AROUND AN INCH FOR THE SAN
BERNARDINO MOUNTAINS AND THE SANTA ANA MOUNTAINS. STAY TUNED FOR
MORE DETAILS ABOUT THIS LOW PRESSURE SYSTEM IN THE COMING DAYS
AGAIN.
AVIATION
171000Z...EASTERLY WINDS HAVE WEAKENED SOMEWHAT ACROSS THE AREA.
LOCAL GUSTS 25-35 KTS WILL CONTINUE THROUGH THIS MORNING IN THE
VALLEYS WITH MORE PERSISTENT GUSTS 30-45 KTS ALONG COASTAL SLOPES
AND ADJACENT FOOTHILLS, LOCALLY HIGHER FOR EAST-FACING SLOPES.
INTERMITTENT LLWS EXPECTED WHERE WINDS DECOUPLE FROM THE SURFACE
(KONT, KSNA, AND MAYBE KCRQ). EASTERLY WINDS 20-35 KTS CONTINUE FOR
COASTAL SLOPES AND PORTIONS OF THE VALLEYS THIS AFTERNOON. WINDS
WEAKEN FURTHER AND BECOME CONFINED TO COASTAL SLOPES AFTER 06Z SUN.
OTHERWISE...VFR CONDITIONS EXPECTED WITH SCT-BKN HIGH CLOUDS THROUGH
TODAY. HIGH CLOUDS SCATTER OUT ACROSS THE AREA TONIGHT.
MARINE
ISOLATED NORTHEAST GUSTS COULD EXCEED 20 KNOTS THROUGH THIS
AFTERNOON. OTHERWISE, NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED
THROUGH WEDNESDAY.
BEACHES
A SOUTH SWELL INCREASING SUNDAY AND MONDAY WILL BRING ELEVATED SURF
OF 3 TO 6 FEET FOR SUNDAY THROUGH TUESDAY. SETS TO 7 FEET ALONG
SOUTH AND SOUTHWEST-FACING BEACHES. WHILE SURF AND RIP CURRENTS WILL
BE ELEVATED, HIGH TIDES WILL NOT BE PARTICULARLY HIGH, AND THE
THREAT OF COASTAL FLOODING IS MINIMAL.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORANGE COUNTY
COASTAL AREAS-ORANGE COUNTY INLAND AREAS-SAN DIEGO COUNTY
COASTAL AREAS.
HIGH WIND WARNING UNTIL 8 PM PDT THIS EVENING FOR SAN BERNARDINO
AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO
COUNTY VALLEYS.
HIGH WIND WARNING UNTIL MIDNIGHT PDT TONIGHT FOR RIVERSIDE
COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS-SAN GORGONIO
PASS NEAR BANNING.
HIGH WIND WARNING UNTIL NOON PDT TODAY FOR SANTA ANA MOUNTAINS
AND FOOTHILLS.
WIND ADVISORY UNTIL NOON PDT TODAY FOR ORANGE COUNTY INLAND
AREAS.
PZ...NONE.
PUBLIC...STEWEY
AVIATION/MARINE/BEACHES...KW
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