Local rainfall measurements show this year’s rainy season already surpassing totals for each year since the 2018-19 season, with just the past month’s rainfall close to the entire precipitation totals for each of the previous 3 years.
Data reported by the Community Collaborative Rain Hail & Snow Network show that storms have dumped more than 6 inches of rain on the Tracy area since the last week of December, bringing the season total to 9.29 inches as of Wednesday.
That’s more than the seasonal totals – July through June -- for the past 3 years, including 2019-20 (6.08 inches), 2020-21 (5.09 inches) and 2021-22 (7.00). Before that the seasonal total for 2018-19 was 11.16 inches for Tracy.
This season’s total includes 6.21 inches from Dec. 27 through Wednesday. The network reported that the highest 24-hour total so far this season was from 7 a.m. Sunday to 7 a.m. Monday (1.56 inches), right before floodwaters again spread through the Tracy area and the floodplain between Corral Hollow Creek and the San Joaquin River.
Precipitation totals vary among measuring stations around San Joaquin County, with the National Weather Service Sacramento office measuring rainfall for San Joaquin County at Stockton Metropolitan Airport. Those totals tend to be higher than those measured in Tracy by the Community Collaborative Rain Hail & Snow Network, but still show that this year’s storms pack the most precipitation that this area has seen in at least 3 years.
The seasonal average as reported by the National Weather Service is 13.45 inches. The last time the area saw that much rain was 2018-19 (18.37 inches), and the time before that was 2016-17 (21.78 inches). In 4 of the last 5 years the area has received less than 10 inches of rain, including 2017-18 (9.23 inches), 2019-20 (8.58 inches), 2020-21 (7.88 inches) and 2021-22 (9.82 inches), according to NWS data.
So far 2022-23 has seen 15.32 inches at the Stockton Metropolitan Airport since July, already above the season average. That includes 8.5 inches in December and 5.52 inches so far in January.
The National Weather Service predicted that after Wednesday night’s showers the area would see mostly clear skies for the next week, though temperatures are expected to drop to the mid to low 30s.
Local floodwaters should also recede in that time. The San Joaquin River at the Airport Way/Durham Ferry Road bridge, where the U.S. Geographical Survey has its Vernalis gaging station, reached 22 feet Monday, passed the monitor stage of the river (24.5 feet) Tuesday night, and was at 25.69 feet Wednesday night, peaking below the flood stage (29 feet). The National Weather Service California Nevada River Forecast Center expected the river level to start receding by Thursday morning.
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