High pressure ridging became the dominant weather feature during March 8th-10th and brought warm, dry conditions to the area; temperatures were at least several degrees above the seasonal average during much of this period.
The ridge somewhat weakened on March 11th through the 13th, as temperatures cooled down closer to seasonal averages. However, high pressure rebounded once again on March 14th and 15th, and temperatures returned to several degrees above average. This pattern basically remained dry and was similar to what occurred during much of the previous week in terms of temperatures.
On the 16th, an upper-level trough brought abundant moisture to the northern part of interior central California during the evening. By the 17th, the upper-level low was located along the central California coast and brought much convective activity to the area. Most of the rain fell during the morning hours on the 17th.
The ���Saint Patrick���s weekend��� storm will be remembered for not only record-smashing rain, but also for a tornado that hit western Fresno County. The rain began during the evening of March 16th, and by daybreak the next morning the California Highway Patrol was reporting flooding in the south end of the San Joaquin Valley. As the cold front move through the Fresno-Clovis area around 2:30 AM, a burst of strong winds���later estimated at 55-60 mph���toppled trees and caused some structural damage.
Over two feet of snow had fallen at Tuolumne Meadows by 8:45 AM, and mud and debris flows were reported in the Southern Sierra Nevada foothills. Less than 45 minutes later, winds gusted to 72 mph at Indian Wells Canyon near the south end of the Sierra Nevada.
By midday, both Bakersfield and Fresno had surpassed their rainfall records for March 17th. Hail fell on parts of Kerman, Visalia and Tulare. Winds gusted to 55 mph at Sunflower Valley in northwestern Kern County, and to 40 mph at Buttonwillow.
At 3:30 PM, a tornado was photographed on the ground near Mountain View Road and State Route 33, west southwest of the town of Tranquility in western Fresno County. This tornado touched down in an open field, and fortunately caused no injuries or damage. This was the 85th tornado since 1950 for the seven counties of the central California interior, and the first since February 27, 2010, when a tornado touched down in southwestern Kern County.
The CHP reported a rock slide on Highway 140 at Highway 49 in Mariposa County at 11:10 AM on the 17th.
By the time the storm had ended on March 18th, nearly 2.78 inches of rain had fallen at the Madera Municipal Airport, while Fresno had 1.78 inch and Bakersfield had 0.96 inch of rain. In the higher elevations of the Southern Sierra Nevada, new snow totals were up to 43 inches.
Most of the cold air behind the upper-level low arrived by the 18th. More convection developed over the San Joaquin Valley and nearby foothills. Numerous reports of pea-sized hail with about one inch of ground cover were received throughout the valley and caused some damage to crops, especially those with blossoms. High temperatures in the central and southern San Joaquin Valley on March 18th were mostly in the 50s, well below the normals of md to upper 60s.
Eight inches of snow fell at Camp Nelson, with the heavy snow knocking down trees and causing power outages. In addition, snow levels fell below 2,000 feet in the Sierra Nevada foothills, especially in heavier showers. On the evening of the 18th, the storm system began to exit the region.
The 19th was a transitional day while an upper level ridge moved toward the central coast and kept interior central California underneath a cool north-northwest flow aloft.
By the 20th, high pressure began to strengthen and allowed temperatures to recover; they rose to a few degrees above seasonal averages by the 21st. This pattern continued for the next couple of days until another low pressure system arrived on the 24th.

Winter Storm in S SIERRA MTNS, CALIFORNIA
From 16-MAR-12 22:00:00 to 17-MAR-12 20:57:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Winter Storm in TULARE CTY MTNS, CALIFORNIA
From 16-MAR-12 22:00:00 to 17-MAR-12 20:57:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Winter Storm in KERN CTY MTNS, CALIFORNIA
From 16-MAR-12 22:00:00 to 17-MAR-12 18:30:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Winter Weather in S SIERRA FOOTHILLS, CALIFORNIA
From 16-MAR-12 22:00:00 to 17-MAR-12 18:30:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in TULARE CTY FOOTHILLS, CALIFORNIA
From 16-MAR-12 22:00:00 to 17-MAR-12 18:30:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Flood in FRESNO, CALIFORNIA
From 17-MAR-12 08:30:00 to 17-MAR-12 11:30:00 (PST-8)
Location: KERMAN
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Debris Flow in S SIERRA FOOTHILLS, CALIFORNIA
From 17-MAR-12 10:10:00 to 17-MAR-12 11:10:00 (PST-8)
Property damage: 8.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flood in FRESNO, CALIFORNIA
From 17-MAR-12 08:30:00 to 17-MAR-12 09:30:00 (PST-8)
Location: KERMAN
Flood cause: Heavy Rain
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained storm spotter reported flooding west of Fresno.

Thunderstorm Wind in FRESNO, CALIFORNIA
From 17-MAR-12 01:30:00 to 17-MAR-12 01:30:00 (PST-8)
Location: GLORIETTA
Magnitude: 50.00 EG
Property damage: 1.00M
Crop damage: 0.00K
Reported by: NWS Storm Survey

NWS Storm survey team investigated wind damage on the north side of Clovis and determined that a severe thunderstorm produced straight line wind damage at around 230 AM.  Several large evergreen trees were downed on homes on the north side of Clovis.

Tornado in FRESNO, CALIFORNIA
From 17-MAR-12 14:30:00 to 17-MAR-12 14:30:00 (PST-8)
Location: TRANQUILITY
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Broadcasters captured a tornado WSW of the town of Tranquility. No damage or injuries were reported.

Heavy Rain in MARIPOSA, CALIFORNIA
From 17-MAR-12 07:15:00 to 17-MAR-12 08:15:00 (PST-8)
Location: DARRAH
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A Co op observer reported overnight rainfall total of 3.15 inches.

Flood in KERN, CALIFORNIA
From 17-MAR-12 05:30:00 to 17-MAR-12 06:30:00 (PST-8)
Location: LAKEVIEW
Flood cause: Heavy Rain
Property damage: 12.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The highway patrol reported flooding on CA Highway 166 at Old River Road.

Flood in KERN, CALIFORNIA
From 17-MAR-12 09:39:00 to 17-MAR-12 10:39:00 (PST-8)
Location: BAKERSFIELD
Flood cause: Heavy Rain
Property damage: 6.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California highway patrol reported flooding on Michelle Avenue at Shawn Street.