Strong northwest flow and a weak shortwave combined to bring predominantly wind advisory level winds to the mountains and deserts from the 21st to the 22nd of December. A long duration stratiform rain event also occurred, with the bulk of the rain falling from the 21st through the 23rd.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SGX wrote it up.
Strong northwest flow and a weak shortwave combined to bring predominantly wind advisory level winds to the mountains and deserts from the 21st to the 22nd of December. A long duration stratiform rain event also occurred, with the bulk of the rain falling from the 21st through the 23rd. Coastal areas received predominantly 0.10 to 0.50 inches of rainfall, while strong upslope flow produced 2 to 4 inches of rainfall along the southwest facing slopes of the mountains.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before the first event at Dec 22, 2:58 AM PST, 4 hours 16 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
258 AM PST TUE DEC 22 2015
.SYNOPSIS...
THROUGH EARLY WEDNESDAY...A MILD MOIST WEST NORTHWEST FLOW PATTERN
WILL BRING STRONG GUSTY WEST WINDS TO THE MOUNTAINS AND DESERTS...
AND PERIODS OF RAIN FROM THE MOUNTAINS WESTWARD WITH THE GREATEST
RAINFALL THROUGH TODAY. DRYING FOR LATE WEDNESDAY INTO THURSDAY.
FOR THURSDAY NIGHT INTO CHRISTMAS DAY...A TROUGH OF LOW PRESSURE
MOVING INLAND THROUGH THE WESTERN STATES WILL BRING COOLING...GUSTY
WEST WINDS IN THE MOUNTAINS AND DESERTS...AND A CHANCE OF SHOWERS.
COLD NIGHTS AND SLOW DAYTIME WARMING WILL FOLLOW FOR THE WEEKEND
WITH PERIODS OF GUSTY NORTH TO NORTHEAST WINDS. WARMING TO NEAR
AVERAGE FOR EARLY NEXT WEEK.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH THURSDAY)...
A MOIST WEST NORTHWEST FLOW PATTERN WILL CONTINUE INTO EARLY
WEDNESDAY. THIS WILL BRING STRONGER ONSHORE FLOW WITH PERIODS OF
STRONG GUST WEST WINDS THROUGH LATE TONIGHT FOR THE MOUNTAINS...
PORTIONS OF THE DESERTS...AND AREAS NEAR THE COAST. STRONGEST
WINDS ARE EXPECTED THIS AFTERNOON AND EVENING NEAR MOUNTAIN RIDGE
TOPS AND ALONG DESERT MOUNTAIN SLOPES...ESPECIALLY FOR THE
MOUNTAIN RANGES IN RIVERSIDE AND SAN DIEGO COUNTIES. WINDS WILL
GRADUALLY DIMINISH LATE TONIGHT INTO WEDNESDAY MORNING. STRONGEST
WIND GUSTS THROUGH 230 AM TODAY OF 50 TO 60 MPH IN THE SAN DIEGO
COUNTY MOUNTAINS NEAR THE HIGHER PEAKS AND IN THE NORTHERN
COACHELLA VALLEY BELOW THE SAN GORGONIO PASS.
AREAS OF MOSTLY LIGHT RAIN DEVELOPED MONDAY EVENING ALONG AND WEST
OF THE MOUNTAINS AND HAS CONTINUED OVERNIGHT. THROUGH EARLY
WEDNESDAY...THIS MOIST WEST NORTHWEST FLOW WILL BRING PERIODS OF
RAIN ALONG AND WEST OF THE MOUNTAINS WITH GREATEST AMOUNTS ON WEST
FACING MOUNTAIN SLOPES. SNOW LEVELS WILL BE MOSTLY ABOVE 6500 TO
7000 FEET.
RAINFALL AMOUNTS WILL BE MORE MODEST NEAR THE COAST...BUT COULD BE
SIGNIFICANTLY MORE ON WEST FACING MOUNTAIN SLOPES WHERE STRONG
ONSHORE FLOW PROVIDES OROGRAPHIC LIFT OF A PLUME OF MOISTURE WITH
PRECIPITABLE WATER VALUES OF AROUND ONE INCH...ABOUT 200 PERCENT
OF NORMAL.
RAINFALL AMOUNTS THROUGH EARLY WEDNESDAY MORNING COULD RANGE FROM
ONE TENTH TO ONE QUARTER INCH AT THE COAST TO ONE TO ONE AND ONE
HALF INCHES ON WEST FACING MOUNTAIN SLOPES WITH LOCAL AMOUNTS
EXCEEDING TWO INCHES. SEVERAL INCHES OF SNOW COULD FALL ON HIGHER
MOUNTAIN PEAKS...MOSTLY ABOVE 7000 FEET.
THE BULK OF THE PRECIPITATION IS EXPECTED TO OCCUR THROUGH
TODAY...WITH RAIN GRADUALLY ENDING FROM THE NORTHWEST TONIGHT
THROUGH EARLY WEDNESDAY.
THEN DRY THROUGH THURSDAY AFTERNOON WITH HIGH TEMPERATURES
REMAINING A LITTLE BELOW AVERAGE.
&&
.LONG TERM (THURSDAY NIGHT THROUGH MONDAY)...
A LOW PRESSURE SYSTEM WILL MOVE INLAND THROUGH THE WESTERN STATES
FOR THURSDAY AND FRIDAY. THE SURFACE COLD FRONT WILL BRING A
PERIOD OF MAINLY LIGHT SHOWERS FOR LATE THURSDAY NIGHT INTO EARLY
CHRISTMAS MORNING. CHRISTMAS DAY WILL BE QUITE COOL WITH HIGH
TEMPERATURES AROUND 5 DEGREES BELOW AVERAGE FOR ELEVATIONS BELOW
1000 FEET...AND 10 TO 15 DEGREES BELOW AVERAGE ELSEWHERE.
AS THIS LOW PRESSURE SYSTEM MOVES INTO THE SOUTHWEST STATES FOR
THE WEEKEND...NORTH WINDS ALOFT AND SURFACE HIGH PRESSURE OVER THE
GREAT BASIN WILL BRING PERIODS OF STRONG GUSTY NORTH TO NORTHEAST
WINDS NEAR AND BELOW COASTAL MOUNTAIN SLOPES. HIGH TEMPERATURES
WILL WARM SLOWLY THROUGH SUNDAY...BUT REMAIN A LITTLE BELOW
AVERAGE FOR SUNDAY. NIGHTS WILL BE QUITE COOL WITH AREAS OF FROST
POSSIBLE IN WIND SHELTERED LOCATIONS IN VALLEY AND SOME COASTAL
AREAS EARLY SATURDAY AND SUNDAY MORNINGS. LOW TEMPERATURES COULD
FALL INTO THE 20S BOTH OF THOSE MORNINGS IN THE COLDEST WIND
SHELTERED LOCATIONS IN THE INLAND VALLEYS.
FOR MONDAY...THE GFS AND ECMWF ENSEMBLE MEANS AND THE ECMWF ARE IN
GENERAL AGREEMENT IN MOVING A WEAK LOW PRESSURE SYSTEM INTO
CALIFORNIA. THIS WOULD BE MOSTLY DRY AND KEEP HIGH TEMPERATURES A
LITTLE BELOW AVERAGE.
&&
.AVIATION...
221000Z...LOW CLOUDS AND SHOWERS WILL CONTINUE MOUNTAINS WESTWARD
THROUGH THE DAY AND A LAYER AT ABOUT 10000 FEET MSL OVER DESERTS.
THROUGH 17Z CIGS COULD BE AS LOW AS 800 FEET MSL AND VIS AS LOW AS
1SM IN RAIN. IN GENERAL CIGS WILL VARY FROM 1500-2500 FEET MSL WITH
LAYERS REACHING UP OVER 10000 FEET MSL. MOST TERRAIN ON COASTAL
SLOPES WILL BE OBSCURED AT LEAST THROUGH THE MORNING. GENERAL
LIFTING OF CLOUD BASES WILL OCCUR AFTER 00Z THIS AFTERNOON AND
TONIGHT. AREAS OF STRONG WEST WINDS WILL CONTINUE ALONG MOUNTAIN
CRESTS AND ADJACENT DESERT SLOPES THROUGH THIS EVENING. THESE MAY
CAUSE BRIEF LOCAL ROTORS OR STRONG UP/DOWN DRAFTS IN LEE OF
MOUNTAINS.
&&
.MARINE...
200 AM...WESTERLY WINDS AND A NORTHWEST SWELL WILL BE ON THE
INCREASE TODAY. CHOPPY AND HAZARDOUS BOATING CONDITIONS WILL RESULT.
SEE THE SMALL CRAFT ADVISORY FOR DETAILS...LAXMWWSGX. WINDS DIMINISH
WEDNESDAY AND SEAS DECREASE WEDNESDAY NIGHT...BUT WINDS AND SEAS
WILL INCREASE AGAIN THURSDAY NIGHT AND FRIDAY.
&&
.BEACHES...
200 AM...VERY HIGH TIDES DURING THE MORNINGS TODAY THROUGH FRIDAY
WILL CAUSE SOME COASTAL FLOODING OF LOWEST LYING AREAS. AN INCREASE
IN SURF WEDNESDAY THROUGH FRIDAY WILL ADD TO THE COASTAL FLOODING
THREAT. FOR DETAILS CHECK THE COASTAL FLOOD ADVISORY...LAXCFWSGX.
&&
.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY UNTIL 10 AM PST WEDNESDAY FOR APPLE AND LUCERNE
VALLEYS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY
MOUNTAINS-SAN DIEGO COUNTY DESERTS-SAN DIEGO COUNTY
MOUNTAINS-SAN GORGONIO PASS NEAR BANNING.
WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM PST THIS EVENING
FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL
AREAS.
COASTAL FLOOD ADVISORY UNTIL 10 AM PST FRIDAY FOR ORANGE COUNTY
COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.
PZ...SMALL CRAFT ADVISORY UNTIL 8 PM PST WEDNESDAY FOR WATERS FROM
SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM
OUT INCLUDING SAN CLEMENTE ISLAND.
SMALL CRAFT ADVISORY UNTIL 10 AM PST WEDNESDAY FOR COASTAL
WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT
TO 30 NM.
&&
PUBLIC...17
AVIATION/MARINE...MMThe national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
The Otay Mountain mesonet station reported sustained winds in the low to mid 40s with a gust of 58 mph.
The Harrison Park mesonet station reported sustained winds to 51 mph and a wind gust of 70 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2015Every state in 2015This day in weather historyWarnings in California, December 2015
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 608634, 608633.