A weak, upper-level trough of low pressure moved through the West on the 16th, with scattered showers and high elevation snow. Showers lingered through the night, before a second, stronger trough moved through the region on the 17th.
Every event with a place to put it; 1 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.
A weak, upper-level trough of low pressure moved through the West on the 16th, with scattered showers and high elevation snow. Showers lingered through the night, before a second, stronger trough moved through the region on the 17th. Showers increased in coverage and intensity with the second trough, behind a leading line of strong thunderstorms, with scattered thunderstorms behind it. Significant lightning activity occurred with this initial, organized line of thunderstorms between approximately 2200 PST on the 16th and 0400 PST on the 17th. Post-frontal showers continued, with a few reports of small hail, and a funnel cloud at Riverside March Field. Two-day rainfall totals varied widely with the coast and valley locations receiving between one-tenth and almost one inch of rain, but most saw between one-quarter and three-quarters of an inch. Coastal mountain slope locations received up to 1.3 inches of rain, while the deserts ranged from a few hundredths of an inch to one-third of an inch (highest amounts in the upper deserts). Several roads were closed due to flooding in San Marcos, Spring Valley and a mud/debris flow along Highway 91 in Corona. The snow level lowered to 4500-5000 feet, with two-day accumulations of up to 4 inches below 6000 feet and up to 10 inches between 6000-8000 feet.
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 15, 9:00 PM PST, 7 hours earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
900 PM PST MON DEC 15 2014
.SYNOPSIS...
A LOW PRESSURE TROUGH WILL BRING SCATTERED SHOWERS TUESDAY. A
SECOND...STRONGER TROUGH WILL BRING MORE WIDESPREAD AND HEAVIER
SHOWERS WEDNESDAY. THIS SECOND SYSTEM IS COLDER AND WILL LOWER SNOW
LEVELS TO 5000 FEET WEDNESDAY. SEVERAL INCHES OF SNOW ACCUMULATING
ARE EXPECTED ABOVE 6000 FEET. DRY WITH A WARMING TREND THURSDAY
AFTERNOON THROUGH FRIDAY. A WEAK TROUGH MAY PRODUCE SCATTERED LIGHT
SHOWERS OVER THE WEEKEND. WARMER WITH DRY OFFSHORE FLOW EARLY NEXT
WEEK.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A BAND OF MODERATE TO HEAVY RAIN ROUNDED POINT CONCEPTION THIS
EVENING AND WILL MOVE SOUTHEAST ACROSS VENTURA COUNTY AND L.A.
COUNTIES THROUGH MIDNIGHT. THE HEAVIEST CELLS PRODUCED .25" BETWEEN
6-7PM OVER THE CHANNEL ISLANDS. THE LEADING EDGE OF THIS CONVECTIVE
BAND WILL REACH WESTERN ORANGE COUNTY/SAN BERNARDINO COUNTY AFTER
MIDNIGHT AND THEN SPREAD SOUTHEAST ACROSS SAN DIEGO COUNTY LATE
TUESDAY MORNING. IT IS MOVING INTO AN AREA OF HIGHER CAPE
(500-700J/KG) SO THE LINE SHOULD MAINTAIN ITS STRENGTH AS IT MOVES
ACROSS THE COASTAL WATERS. THE IR SATELLITE LOOP SHOWS A
NARROW...BROKEN LINE OF COOLING CLOUD TOPS ALIGNED WITH THE SURFACE
COLD FRONT OVER THE OUTER WATERS.
BEHIND THE FRONT ON TUESDAY AFTERNOON THE THERMODYNAMIC PROFILE
FAVORS WIDELY SCATTERED SHOWERS WITH COLDER AIR ALOFT IN A
MODERATELY UNSTABLE AIRMASS. UPWARD VERTICAL MOTIONS WILL BE
ENHANCED BY ANY EMBEDDED WEAK SHORTWAVES IN BROAD CYCLONIC FLOW
ALOFT AND INCREASE THE COVERAGE OF THE AFTERNOON SHOWERS. THE SNOW
LEVEL WILL FALL TO 6000 FEET MIDDAY TUESDAY.
THE PRECIP COVERAGE INCREASES LATE TUESDAY NIGHT AHEAD OF A STRONGER
SHORTWAVE. THIS SECOND TROUGH WILL HAVE STRONGER UPPER JET
DYNAMICS...AN INCREASE IN THE ONSHORE FLOW AND A PW SURGE NEAR 1.00"
INTO SOCAL EARLY WEDNESDAY MORNING. GREATER INSTABILITY WITH THIS
SECOND SHORTWAVE WILL BRING A CHANCE OF HEAVY SHOWERS OR EVEN A FEW
THUNDERSTORMS WEDNESDAY. THIS SYSTEM WILL BE MOSTLY CONVECTIVE IN
NATURE, BUT THERE IS SOME OROGRAPHIC POTENTIAL AHEAD OF THE FRONT
OVER THE SAN BERNARDINO MOUNTAINS...AND THEN BEHIND THE FRONT OVER
THE SAN JACINTO AND SAN DIEGO COUNTY MOUNTAINS. SNOW LEVELS WILL
LOWER TO 5000-5550 FEET WITH SEVERAL INCHES OF SNOW ABOVE 6000 FEET.
THE SHOWERS WILL END IN MOST AREAS WEDNESDAY NIGHT WITH WEAK RIDGING
ALOFT AND DRY WEATHER THURSDAY INTO FRIDAY.
A THIRD...WEAKER TROUGH WILL BRING A CHANCE FOR A FEW MORE LIGHT
SHOWERS OVER THE WEEKEND. FOR EARLY NEXT WEEK...THE MODELS ARE
KEYING IN ON THE DEVELOPMENT OF A STRONG RIDGE OVER THE EASTPAC THIS
WEEKEND WITH HIGH PRESSURE AND DRY OFFSHORE FLOW EARLY NEXT WEEK.
&&
.HYDROLOGY...
FOR THE INITIAL SHORTWAVE AND WEAKENING FRONT ON TUE...EXPECT SOME
SHOWERS TO ARRIVE ACROSS ORANGE AND SAN BERNARDINO COUNTIES EARLY
TUE MORNING..AND SPREAD SOUTH THROUGH SAN DIEGO COUNTY THROUGH
MIDDAY. OROGRAPHIC EFFECTS LOOK MINIMAL...SO PRELIMINARY RAINFALL
ESTIMATES ARE FOR ONE-HALF TO LOCALLY ONE INCH IN THE SAN BERNARDINO
MTS...WITH AROUND ONE-QUARTER TO NEAR ONE-HALF INCH FARTHER SOUTH
THROUGH EARLY EVENING. THE SNOW LEVEL IS EXPECTED TO BE BETWEEN 5500
AND 6000 FEET WITH SEVERAL INCHES OF SNOW POSSIBLE ON THE HIGHER
PEAKS OF THE SAN JACINTO AND SAN BERNARDINO MTS. A WINTER WEATHER
ADVISORY HAS BEEN POSTED IN THE SAN BERNARDINO MTS AFTER MIDNIGHT
THROUGH TUE ABOVE 6000 FT.
SCATTERED...SHOWERS AND ISOLATED THUNDERSTORMS MAY CONTINUE TUE
NIGHT INTO EARLY WED MORNING...THEN EXPECT RAIN/SNOW SHOWERS TO
INCREASE AND BECOME MORE WIDESPREAD WED AHEAD OF THE COLDER TROUGH.
THIS EVENT WILL BE MORE CONVECTIVE...SO RAIN AND SNOWFALL WILL BE
MORE VARIABLE...BUT THERE IS A POTENTIAL FOR AN ADDITIONAL ONE-HALF
TO ONE INCH OF RAIN MOST AREAS ALONG AND WEST OF THE MTS BY THU
MORNING...AND LOCALLY HEAVY SNOW ABOVE 5500 FT. CONFIDENCE REMAINS
LOW TO MODERATE WITH THIS EVENT DUE TO UNCERTAINTY ASSOCIATED WITH
THE EXACT TRACK OF THE SYSTEM...AND THE SHOWERY NATURE EXPECTED.
AVAILABLE PW WILL AGAIN BE CLOSE TO ONE INCH...SO MOISTURE WILL BE
SUFFICIENT. INSTABILITY PARAMETERS ARE ELEVATED AND SUGGEST A THREAT
OF ISOLATED THUNDERSTORMS...LATE TUE NIGHT THROUGH WED. THE SHOWERS
WILL WIND DOWN WED NIGHT AND ARE EXPECTED TO END EARLY THU MORNING
OVER THE SAN DIEGO COUNTY MTS.
SINCE MORE WIDESPREAD AND HEAVIER SHOWERS ARE EXPECTED ON WED...SOME
RESPONSE IN AREA STREAMS AND RIVERS IS LIKELY. RAINFALL MAY BE
SUFFICIENT TO ELEVATE THE SAN DIEGO RIVER AGAIN SEVERAL FEET TO NEAR
MONITOR/ACTION STAGE WED AFTERNOON/EVENING WITH ASSOCIATED
INUNDATION OF ADJACENT LOW-LYING AREAS AND CROSSINGS.
BASED ON THE CHANCE OF HEAVY RAINFALL RATES...A FLASH FLOOD WATCH
HAS BEEN ISSUED FOR AREAS IN AND BELOW THE SILVERADO BURN SCAR AND
BELOW THE MOUNTAIN BURN SCAR INCLUDING THE HEMET AREA BEGINNING TUE
AFTERNOON WITH THE MAIN THREAT INLAND COMING ON WEDNESDAY DUE TO
POSSIBLE HEAVY CONVECTIVE SHOWERS/THUNDERSTORMS WITH RAINFALL BURSTS
OF ONE-HALF INCH PER HALF HOUR...OR MORE.
&&
.AVIATION...
160400Z...COASTS/VALLEYS/MOUNTAINS...MULTIPLE SCT-BKN CLOUD LAYERS
2500-5000 FT MSL BECOMING BKN-OVC TONIGHT AS A COLD FRONT
APPROACHES. WIDESPREAD -SHRA BEGINNING ALONG THE COAST
10-12Z...SPREADING SOUTHEAST THROUGH 18Z. SHOWERS BECOMING ISO-SCT
DURING THE AFTERNOON WITH A SLIGHT CHC OF THUNDERSTORMS AFTER ABOUT
18Z AND CONTINUING INTO TUE NIGHT. LOCAL VIS 3-5SM IN HEAVIER
SHOWERS AND MOUNTAIN OBSCURATIONS IN CLOUDS/FOG...OTHERWISE VIS
UNRESTRICTED AND SCT-BKN CLOUDS AOA 10000 FT MSL.
DESERTS...SCT -SHRA POSSIBLE IN THE HIGH DESERT BETWEEN 12-21Z.
OTHERWISE SCT-BKN CLOUDS AOA 10000 FT AND UNRESTRICTED VIS THROUGH
TUE EVENING.
&&
.MARINE...
800 PM...SOUTH WINDS WILL INCREASE THIS EVENING AHEAD OF A COLD
FRONT...BECOMING WESTERLY AND WEAKENING LATE TUE MORNING. SOUTH
WINDS STRENGTHENING AGAIN TUESDAY NIGHT AHEAD OF A SECOND COLD
FRONT. GUSTY WEST-NORTHWEST WINDS MOVE OVER THE COASTAL WATERS
BEHIND THE SECOND FRONT WED MORNING WITH GUSTS AS HIGH AS 25-30 KT.
WINDS WILL SLOWLY WEAKEN THROUGH EARLY THU MORNING. IN ADDITION...A
LARGE WEST SWELL WILL ARRIVE TONIGHT AND PEAK TUESDAY...WITH
COMBINED SEAS ABOVE 10 FEET OVER PORTIONS OF THE WATERS. A SMALL
CRAFT ADVISORY IS IN EFFECT FOR STRONG WINDS AND LARGE SEAS THROUGH
WED EVENING. SEE LAXMWWSGX.
THESE COLD FRONTS WILL ALSO BRING THE POTENTIAL FOR ISOLATED
THUNDERSTORMS TUESDAY AFTERNOON INTO WED EVENING...SOME OF WHICH MAY
PRODUCE WATERSPOUTS AND STRONG AND GUSTY WINDS. SEE LAXMWSSGX FOR
MORE DETAILS.
&&
.BEACHES...
810 PM...A LARGE WEST SWELL WILL BUILD TONIGHT AND PEAK TUESDAY AT
10-11 FEET/16-17 SECONDS...LIKELY BRINGING HIGH SURF OF 6 TO 9 FEET
AND ISOLATED HIGHER SETS LATE TONIGHT INTO TUESDAY. STRONG RIP
CURRENTS ARE LIKELY AS WELL. THE SWELL AND SURF WILL SLOWLY SUBSIDE
LATE TUESDAY INTO WEDNESDAY. A HIGH SURF ADVISORY REMAINS IN EFFECT
THROUGH WEDNESDAY MORNING.
ANOTHER LARGE...LONG PERIOD WEST SWELL WILL ARRIVE LATE SATURDAY AND
PEAK ON SUNDAY...BRINGING YET ANOTHER ROUND OF ELEVATED SURF AND
STRONG RIP CURRENTS. THE COMBINATION OF ELEVATED SURF AND MORNING
HIGH TIDES OVER 7 FEET MAY RESULT IN MINOR TIDAL OVERFLOW AT LOW
LYING BEACH AREAS.
&&
.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...HIGH SURF ADVISORY UNTIL NOON PST WEDNESDAY FOR THE
BEACHES IN THE ORANGE COUNTY COASTAL AREAS...SAN
DIEGO COUNTY COASTAL AREAS.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM PST
TUESDAY ABOVE 6000 FEET FOR THE SAN BERNARDINO COUNTY
MOUNTAINS.
WINTER STORM WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY
AFTERNOON ABOVE 5500 FEET FOR THE SAN BERNARDINO COUNTY
MOUNTAINS.
FLASH FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
AFTERNOON FOR THE RIVERSIDE COUNTY MOUNTAINS...SANTA ANA
MOUNTAINS AND FOOTHILLS.
WINTER WEATHER ADVISORY FROM 6 AM TO 8 PM PST WEDNESDAY FOR THE
RIVERSIDE COUNTY MOUNTAINS...SAN DIEGO COUNTY MOUNTAINS.
PZ...SMALL CRAFT ADVISORY UNTIL 10 PM PST WEDNESDAY FOR THE
BEACHES IN THE COASTAL WATERS FROM SAN MATEO POINT TO
THE MEXICAN BORDER AND OUT 30 NM...WATERS FROM SAN MATEO
POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT
INCLUDING SAN CLEMENTE ISLAND.
&&
PUBLIC...MOEDE
HYDROLOGY...JAD
AVIATION/MARINE/BEACHES...22The San Diego radar (KNKX), 28 km away, was scanning. The volume nearest the first event began at 22:59 UTC.
2 flood, 1 high surf, 1 debris flow, 1 funnel cloud. Local standard time, as filed.
Surfline reported 5 to 8 foot surf at Blacks Beach and 5 to 7 foot surf at Ocean Beach.
CHP reported the roadway completely flooded at the I-805 and Highway 94 interchange where a vehicle hydroplaned and overturned. Nearby stations reported instantaneous rainfall rates of 0.25 to 0.40 per hour.
A debris flow of rocks and mud several inches deep covered Highway 91 in Corona. All east-bound lanes were closed at 0200 PST.
Road closed due to flowing water in Escondido Creek over Country Club Drive on low lying crossing. Webcams from SD county flood control confirmed flooding. News 10 reported roadway flooding Along Bent Avenue at Discover Street in San Marcos.
The March AFB AOS observer reported a cold air funnel cloud between 1153-1158 PST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2014Every state in 2014This day in weather historyWarnings in California, December 2014
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: 552627, 552628, 552626, 552633, 552618.