The fourth, and strongest, in a series of winter storms pounded the region on the 21st and 22nd, bringing another round of gusty winds, heavy rain, thunderstorms, several feet of snow in the mountains, and flooding throughout the CWA. Many roads in the region were closed due to flooding and mud on the roadway, as well as fallen trees. In Horsethief Canyon Ranch in Temescal Valley dozens of large trees were uprooted due to the heavy rain and winds, though no other damage was reported. The storm was marked by record-breaking low pressure. Lindbergh Field recorded a sea level pressure of 987.1 mb, shattering the old record of 994.6 mb set on March 3 1983.

Flash Flood in RIVERSIDE, CALIFORNIA
From 21-JAN-10 12:00:00 to 21-JAN-10 13:30:00 (PST-8)
Location: CALIMESA
Flood cause: Heavy Rain / Burn Area
Property damage: 10.00K
Crop damage: 0.00K
Reported by: County Official

San Bernardino County Works reported a debris flow on Pendleton Road in Yucaipa. The hills just above the road had been burned in the 2009 Pendleton Fire. The street was closed off due to flooding, but no other damage was reported. Mud was as deep as 4 feet in some locations.

Strong Wind in SAN DIEGO COUNTY COASTAL AREAS, CALIFORNIA
From 21-JAN-10 07:00:00 to 22-JAN-10 00:00:00 (PST-8)
Magnitude: 35.00 EG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Newspaper

A torrey pine tree fell on a home on Rimini Road in Del Mar. The time of the incident is unknown. No injuries were reported.

Strong Wind in SAN DIEGO COUNTY VALLEYS, CALIFORNIA
From 21-JAN-10 07:35:00 to 22-JAN-10 15:53:00 (PST-8)
Magnitude: 44.00 MG
Property damage: 80.00K
Crop damage: 0.00K
Reported by: ASOS

Wind gusts as high as 51 MPH were measured by the Ramona Airport ASOS. The strong gusty winds began around 0730 PST on the 21st and continued through about 2300 PST on the 22nd. During that time, an oak tree fell on a car driving on Mossey Grade Road in Ramona, trapping two teenagers. Neither were injured. Another large tree was uprooted and fell on a home on 11th Street in Ramona. Numerous other trees fell down around the city. On family on Highland Valley Road lost 17 avocado trees and a pole that powers their well.

Flood in SAN DIEGO, CALIFORNIA
From 21-JAN-10 15:00:00 to 21-JAN-10 20:30:00 (PST-8)
Location: GRANTVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The San Diego River crested just below the 11.3 foot flood stage on the afternoon of the 21st. There were reports of flooding along Ward Road and in the Qualcomm Stadium parking lot in Mission Valley. No damage was reported.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 21-JAN-10 12:25:00 to 21-JAN-10 14:00:00 (PST-8)
Location: RANCHO BERNARDO
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The Mount Woodson mesonet measured a peak wind gust of 62 MPH at 1230 PST as a line of thunderstorms moved over the area. A weather spotter estimated wind gusts in excess of 60 MPH in San Diego Country Estates around 1230 PST. Two large trees were blown down and blocking the road near San Diego Country Estates.

Flood in RIVERSIDE, CALIFORNIA
From 21-JAN-10 07:00:00 to 21-JAN-10 13:30:00 (PST-8)
Location: CABAZON
Flood cause: Heavy Rain
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Newspaper

In Mecca, eight homes had to be evacuated due to flooding. Some residents claimed that flooding has been a problem for years. An auto wrecking business in Indio was also flooded.

Flash Flood in RIVERSIDE, CALIFORNIA
From 21-JAN-10 12:36:00 to 21-JAN-10 14:05:00 (PST-8)
Location: CALIMESA
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: County Official

San Bernardino County Public Works reported debris and mud in several homes in Yucaipa beginning around 1236 PST and continuing through about 1400 PST. The flash flooding may have knocked over power lines along Wildwood Canyon Road near 2nd Street. The flash flood was a result of heavy rain in the region. Large amounts of water and mud flowed out of the hills to the east of Yucaipa and through the Wildwood Canyon Wash. It is likely that the majority of the flooding was due to the wash overflowing.

Heavy Snow in RIVERSIDE COUNTY MOUNTAINS, CALIFORNIA
From 21-JAN-10 00:45:00 to 22-JAN-10 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall began in the Riverside County mountains shortly after midnight on the 21st. Based on rainfall totals at lower elevations, snowfall in the San Bernardino County mountains, and spotter reports, approximately 12 inches of snow fell by 1530 PST. Snowfall finally ended by about 2000 PST on the 22nd. By the time snowfall ended, the Palm Springs Aerial Tramway reported a weekly total of 5 feet of snow.

Heavy Snow in SAN BERNARDINO COUNTY MOUNTAINS, CALIFORNIA
From 21-JAN-10 02:30:00 to 22-JAN-10 22:00:00 (PST-8)
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall began in the San Bernardino County Mountains around 0230 PST on January 21st and continued through about 2200 PST on the 22nd. Several spotters reported 24 hour snow accumulations of 24 to over 32 inches. Some areas received as much as 3 to 4 feet of snow within 36 hours. By the end of the storm, Snow Valley Ski Resort had a total of 80 to 92 inches of new snow for the week, Bear Mountain Ski Resort had 60 to 66 inches, and a spotter in Big Bear City reported 57 inches. Several mobile homes were damaged due to the heavy snow. A 30 foot tall cedar tree fell under the weight of the snow, damaging a fence and some outdoor tables at Broadway Cafe in Big Bear City.

Flash Flood in SAN DIEGO, CALIFORNIA
From 21-JAN-10 10:20:00 to 21-JAN-10 12:00:00 (PST-8)
Location: RINCON
Flood cause: Heavy Rain / Burn Area
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Public

San Diego County Flood Control relayed a report from the public of numerous locations of flooded roadways with mud, rocks, and debris along Highway 76 through the La Jolla Reservation. A newspaper reported two feet of mud in the garage of a home in Rincon. This occurred after heavy rain moved over the 2007 Poomacha Fire burn area.

High Wind in RIVERSIDE COUNTY MOUNTAINS, CALIFORNIA
From 21-JAN-10 12:30:00 to 21-JAN-10 23:30:00 (PST-8)
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

High winds were measured by several RAWS in the Riverside County Mountains between 1230 PST and 2330 PST. Strong Southwest winds ahead of a cold front peaked around 1300 PST. At that time, the Angelus Hill RAWS measured a peak gust of 67 MPH, while the Ranger Peak and Vista Grande RAWS both measured peak gusts of 63 MPH.

Flash Flood in SAN BERNARDINO, CALIFORNIA
From 21-JAN-10 12:30:00 to 21-JAN-10 21:45:00 (PST-8)
Location: HESPERIA ARPT
Flood cause: Heavy Rain
Property damage: 16.00M
Crop damage: 0.00K
Reported by: County Official

Heavy rain in the High Desert produced widespread flash flooding in the cities of Adelanto, Victorville, Hesperia, and Apple Valley. This area, on average, receives about 5 to 6 inches of rain per year. Most of these areas saw that amount of rain in just a few days. Runoff from the San Bernardino Mountains and a rapidly rising Mojave River may have contributed to some of the flooding. Numerous homes, schools, parks, and roads sustained minor to major damage. Some reports claimed as many as 124 homes in San Bernardino County were damaged. On January 28, the Governor of California declared a State of Emergency which included San Bernardino County.

Heavy Snow in SAN DIEGO COUNTY MOUNTAINS, CALIFORNIA
From 21-JAN-10 15:00:00 to 23-JAN-10 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Snowfall began in the San Diego County mountains around 1500 PST on the 21st. By a about 1300 PST on the 22nd, approximately 12 inches of snow had fallen at the Mount Laguna Lodge. The snow finally tapered off by the morning of the 23rd. A spotter also reported very icy road conditions and visibility down to 1/8 mile at times due to blowing snow and fog.

Heavy Rain in RIVERSIDE, CALIFORNIA
From 21-JAN-10 07:00:00 to 21-JAN-10 13:25:00 (PST-8)
Location: WEST PALM SPGS
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Newspaper

Several areas of the Coachella Valley experienced urban flooding on the 21st as another round of heavy rain moved through the region. A Ross store in Palm Springs sustained large amounts of damage as a 20 by 30 foot section of roof collapsed around 945 PST. The collapse also broke pipes for the fire sprinkler system. One store employee suffered minor injuries.