Dust Storm and High Wind in California, January 23 to 24, 2014

One consequence of the dry airmass was that despite the unseasonably warm afternoon high temperatures, strong radiational cooling allowed overnight lows to fall to near normal. Another consequence was that while some fog developed in January, it was usually short-lived and patchy. The lowest visibilities typically were around and after sunrise, when visibilities as low as 200 feet were reported.

The center of the upper-level ridge moved over the Pacific Northwest coast on January 22nd. An upper-level disturbance dropped down the east side of the ridge into the Great Basin on the 23rd. This disturbance generated mid- and high-level clouds that moved westward over the Southern Sierra Nevada due to the clockwise circulation around the ridge center. These clouds produced light precipitation over the mountains and foothills as far south as Sequoia National Park, and sprinkles were reported in Clovis (although nothing fell at the Fresno-Yosemite International Airport).

The main weather story on January 23rd-24th was the strong offshore flow that developed over southern California. Easterly winds over the Tehachapi Mountains and the south end of the Sierra Nevada funneled through the favorably-oriented passes and canyons, creating gusts to around 55 mph at the base of the Grapevine and to 44 mph at Meadows Field in Bakersfield. Before the event ended, gusts to around 70 mph had occurred in the Tehachapi Mountains and to 59 mph in the south end of the San Joaquin Valley.

The strong winds also caused several blowing dust episodes. The strong winds also knocked over trees and powerlines in the Bakersfield area between Noon and 4 pm on the 23rd. A college student at Bakersfield College was injured when a tree fell and struck the student.

The airmass dried and warmed as it descended through the passes, dropping relative humidities down into single digits in parts of the far southern San Joaquin Valley. The combination of very low humidities and strong gusts prompted the issuance of a Red Flag Warning for the Kern County portion of the San Joaquin Valley and the adjacent valley-facing mountain slopes. This was the first time since record began that a Red Flag Warning was issued for any part of the central or southern San Joaquin Valley in January.

The warm downsloping winds gave Bakersfield back-to-back record high temperatures on January 23rd and 24th. The high on the 23rd was 79 degrees (old record was 77, set in 1970), and the high on the 24th was again 79 (old record was 77, set in 1946). Fresno had a high of 78 degrees on January 24th. This not only set a record high for the date, but also tied the record high temperature for the month (last set on January 28th, 1986).

The clouds lingered over the San Joaquin Valley through the night of January 24th-25th. This kept the airmass over the south end of the Valley very warm overnight. Bakersfield’s low for the 24th was 68 degrees. This was both the record high minimum for the date (old record: 53 in 2009) and the record high minimum for the month (old record: 62 on January 13th, 1980).

Record heat continued the next few days. Fresno had a record high of 75 degrees on January 25th, breaking the old record of 70 degrees set in 2009 and 1936. Fresno had another record high temperature the next day, for its ninth day with a high of 70 degrees or greater. This broke the old record of eight 70+ degree days for January, set in 1948.

Bakersfield had a record twelve days at 70 or above in January 2014. The old record was eleven days, also set in 1948.