Fall and The Four Corners
The weather has gradually cooled, enough so this past Sunday morning I actually saw ice under some sprinklers left running overnight. It didn’t feel cold enough for frost, but obviously it was. Of course, by midday the temperature was back to shirtsleeve weather again.
Even though the sycamore leaves are no longer green and lush looking, they haven’t turned yellow and dropped from the branches yet. The color is a dusty brown-orange, as they continue to hang on. I suspect when we have our first good rain, they will all let go at once, covering the ground beneath the trees. If they fall on pavement, the road surface will become slick with the combination of leaves and rain, so be careful. Now if the rains continue to not fall, the leaves on the roadway won’t be much problem.
The only precipitation we’ve had since last spring came six weeks ago on October 3rd, when I recorded 0.55 inches. A bit over half an inch of rain was brought to our area by the surging moisture of a hurricane southwest of Baja. Because there was sufficient moisture to start the grass, early October could have become a nice early start to our rain season. This moisture did not come from the northern source of our fall and winter storms. This came from a spinoff caused by a storm far south of us.
Because there was no follow-up rain, our weather immediately returned to late-summer warm and dry. It did almost nothing toward starting our grass or alleviating our drought conditions. About the best thing it did was to settle the dust, and even that was temporary. The Gulf of Alaska is the breeding ground for storms containing the precipitation we so desperately need. These disturbances rotate in the gulf until they head south along the North American west coast. Some of these low-pressure zones will turn east across the continent quickly, while others continue farther south until the rotation of the earth forces them to turn inland. Once they start east, they continue their path across the United States until they move out over the Atlantic. Thus, a big storm in Los Angeles may become a weather event in New York three or four days later.
The “four corners area” where the states of Arizona, New Mexico, Colorado and Utah meet, is often responsible for the southern half of California remaining dry. During the summer, a high pressure zone will park over the Four Corners. It is the presence of a high which forces every storm coming south out of the Gulf of Alaska to turn east far north of us. Washington, and to some extent Oregon, get summer showers off and on all summer. Because of a stubborn high over Four Corners, most of California and the great southwest remains dry all summer and into the fall months.
Ideally, the high begins to break down as we move into fall. Then the storms coming south from Alaska move down the coast for enough to bring us rain. Some years, the Four Corners High refuses to break down far into the fall and sometimes even into the winter months. Those years our first rain may not fall until late December, January, or even into February.
Fortunately, the plants growing on our foothills are very resilient, and will produce a decent crop of grass even with a short season. As long as the rains do finally show up, and they bring at six to eight inches of precipitation to the foothills, the grass will sprout, grow, and mature. The 2013-14 year had 8.13 inches, and 2014-15 had 7.99 inches. Of course 2015-16 had 21.65 inches, 2016-17 had 24.32 inches, and our 2017-18 dropped back to 11.06 inches. Even the shorter rainfall years provided enough water in the foothills to produce grass. Of course, the lack of snowpack in the mountains meant the aquifers bringing water to the valley were shorted.
Sometimes the very persistent high pressure zone will allow one or two storms to swing far enough south to dump rain on our hills and start the winter grass crop. Then, for reasons unknown, the high parks in the way of the next series of storms, bumping them north of us. This brings an extended dry period between rains. Of course this is hard on the tender grass crop. The lack of storms also means the high country doesn’t receive an adequate snow pack. Without sufficient snow, the aquifers leading to the valley will not fill with adequate water. This is when wells start pumping sand not water.
As of today, November 14th, half-way through November, there is no indication the Four Corners high has any intention of breaking down and allowing storms into our valley and onto our hills and mountains. In fact, as you can see from the picture, there are a whole string of high pressure zones acting like a fence, turning storms east far north of our area.
When will the Four Corners high break down? When will we get our first winter rain? Will there be enough snow in the mountains by spring to fill the aquifers? Only time will reveal those answers. rent Gill lives in Springville. His “Daunt to Dillonwood” column appears regularly in The Porterville Recorder through the generosity of Weisenberger’s Hardware on West Olive in Porterville. If you enjoyed this column, follow his blog at http:// brentgwriter.blogspot. com.