MONTHLY WEATHER SUMMARY
By Jan Null
Golden Gate Weather Services
April 2005

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April of 2005 continued cool and damp over most of the Golden State as another series of upper level troughs of low pressure transitioned across the West Coast. This spread cool air and showers across the northern two-thirds of the state twice during the first week of the month. Then after an almost two week respite another set of short waves brought three separate precipitation events between the 21st and 29th.

Consequently most regions had a wetter than normal month which pushed the statewide average for April 2005 to 104% of normal. Unlike most of the season the North Coast drainages were the biggest winners with a region wide average of 154% of normal. Eureka's 6.54 (225%) for the month made up a lot of lost ground for the season and edged them to near normal to date. Conversely the Southeast Desert area flip-flopped to a dry April with only 39% of normal, largely in part to no rainfall being recorded east of the Imperial Valley. April precipitation across the other regions fell between 91% across the Northeast Interior and 123% of normal for the Central Coast.

The cool wet weather continued to add to the state's snowpack and water supply. And unlike the past few years the southern half of the Sierra has been the largest beneficiary. On May 1st the southern Sierra Nevada was at 182% of their normal water content, with the northern and central areas at 143% and 150% respectively. The 8-Station Northern Sierra Precipitation Accumulation is at 46.10 inches or 101% of normal.

The general troughiness for the month also translated into a chillier than normal April statewide. The San Joaquin drainage was the coolest, averaging 2.5 degrees below normal while the remaining drainages were from .6 degrees to 1.7 degrees below normal.

The series of troughs and associated cutoff lows also produced several instances of severe weather. On April 8th there were at least 5 confirmed tornadoes; four in the Sacramento metropolitan area and another in Merced county. This was a single day record for the Sacramento metro area and brought the number of tornadoes in the Sacramento valley to record twelve for the season! On the 22nd there were about a half dozen funnel cloud reports in the Sacramento Valley along with some gusty thunderstorm winds that did minor damage. The 28th was another day of widespread thunderstorm activity, focused mainly across Central California. A funnel cloud was reported near Salinas and a line of severe thunderstorms swept across the San Joaquin Valley. These thunderstorms produced several more funnels, hail between .75 and 1.25 inches and localized flooding.

A number of daily rainfall records were also established during the month. Eureka set daily rainfall records on April 3rd (.98", previous record .97" in 2003), 7th (1.14" ties 1945 record) and the 9th (1.22", previous record .79" in 1889). The 7th was also a record day in Crescent City with 1.44" surpassing the previous 1995 mark of 1.30". Stockton set a record on April 8th with .64", bettering the previous mark of .54" in 1915. The 28th of April brought at least 10 new rainfall records to the Los Angeles basin, including downtown LA (1.02", previous .72" in 1983) and Long Beach (1.12", previous .39" in 1983).

Page last updated 5/16/05.