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Thursday, December 3, 2015

Fall 2015 Weather Report

The hopeful, whispered rumors of an El Nino-driven wet winter grow louder as multiple rain events have swept across our parched hills. And what a memorable prelude to the winter it has been, with dramatic floods making the national news, low elevation snow keeping mountain drivers on their toes, and a thrilling flush of green in our grasslands emerging even before local holiday decorations. 
A tinge of green lightening the drab of all dormancy in Tunis Canyon. Photo courtesy of Scot Pipkin.
Whether you live locally or not, you probably heard about our brief but intense October rainstorm which sent torrents of water down adjacent steep slopes, ripping open ephemeral drainages, and cementing both Interstate 5 and Highway 58 (and hundreds of travelers) in thick mud flows up to 6 feet deep. Here at the Conservancy headquarters where our proximity to the roar of the interstate requires shouting outside our office, windows and doors were left wide open to hear… Silence. Bird song. Our quiet respite didn’t last long, and luckily nobody was hurt in the flooding, but it was a sharp reminder of the power of weather to quickly transform business as usual. 

Curiously, our eight weather stations recorded only a small blip in precipitation during that regionally significant event. We constantly marvel at the characteristically uncharacteristic patterns of precipitation on Tejon Ranch. With such variable terrain scaling over 6,000 feet elevation and at such a unique topographical nexus between the arid southern San Joaquin Valley, the wedged tail of the massive Sierra Nevada Mountains, the dynamic edge of the very active Transverse Ranges, and the western apex of the Mojave Desert, how a raindrop intercepts this landscape and where it travels is as wildly dynamic and unpredictable as our diverse systems seem to be. 
Above is a schematic illustration of the elevation of our eight weather stations, averaged across the three geographic regions of the Ranch. Below the weather station data is synthesized into three tables, organized by month.

Averaging data from our eight weather stations by geographic region (see illustration and data tables above), it is evident that most of the Ranch intercepted some rain this fall with November, not October, providing the bulk of overall precipitation. Although the singular mid-season deluge appeared significant, the almost weekly storm events throughout the month of November have succeeded in depositing almost triple the amount of precipitation in the San Joaquin Valley—so fascinating! No wonder we are already observing the fresh emergence of plants here—popcornflowers, bluedick lilies, filaree, and grasses. If the trend continues through the winter, as is hopefully projected, we shall keeping our fingers crossed for a memorable wildflower season this spring and a critical boost for our severely drought-stressed natural communities. Here’s to a long cool drink this winter and to the promise of a colorful spring!

Special thanks to Richard and Lisa Chapleau for managing the weather stations and data, and to Richard for analyzing the giant data set! You guys are the best!