Dan's Outside

Changing Seasons

It is the beginning of September, the time of the year when I begin to watch for signs of autumn.

Until a few years ago I still thought that autumn would actually begin in September. Ignoring what the calendar says, in central California it doesn’t. We’ll have warm weather for another 6 weeks or so. Two supporting facts: September is the sunniest time of the year in San Francisco, and September and the first half of October are the peak fire season in California.

However, by now there are a few signs that things will change before long. As early as the last week of August I spotted a few plants starting to change colors in the Sierra Nevada near Yosemite. Last week I noticed a few trees turning yellow/brown and losing leaves in the coastal California hills. Today I noticed that most of the grasses here have started to go from the summer’s golden color to autumn’s gray.

And, for those of us who are weather-obsessive, there are forecast discussions like this one:

MODELS IN AGREEMENT IN DROPPING A CUTOFF LOW DOWN THE WEST COAST TUE
AND WED WITH THE CORE OF THE LOW OVER THE SFO BAY WED NIGHT. THE
ONLY MODEL THAT IS ANY DIFFERENT IS THE NAM WHICH HAS THE CENTER OF
THE LOW OVER THE NRN SAC VALLEY. MODELS HAVE VERY LITTLE MOISTURE
ASSOCIATED WITH THIS SYSTEM AND EXPECT ANY PRECIP OR POSSIBLE
CONVECTIVE ACTIVITY TO REMAIN TO THE NORTH OF OUR CWA AT THIS TIME.
WE WILL LIKELY ONLY SEE SCT CU OVER THE HIGHER TERRAIN IN THE COLD
UNSTABLE AIR ALOFT ON THU. MEDIUM RANGE MODELS DROP AN INSIDE SLIDER
DOWN THE COAST ON SATURDAY AND SUNDAY TO BRING A MUCH COOLER AIRMASS
TO THE REGION. A SYSTEM OF THIS NATURE IS TYPICALLY DRY AND DONT
EXPECT ANY PRECIP ON SAT OR SUN AT THIS TIME…HOWEVER ANOTHER SHORT
WAVE TROUGH DIGS SOUTHWARD OUT OF THE GULF OF ALASKA BEHIND THE
INSIDE SLIDER ON MONDAY…WHICH MAY BRING THE FIRST CHANCE OF
APPRECIABLE PRECIP TO THE DISTRICT SINCE JUNE. HAVE KEPT PRECIP OUT
OF THE FORECAST FOR NOW BUT IF MODELS MAINTAIN CURRENT SOLUTION
PRECIP WILL HAVE TO BE ADDED FOR EARLY NEXT WEEK.

What that cryptic weather-speak is saying is that the storm track is just beginning to drop south.
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September 5, 2005 - Posted by gdanmitchell | Commentary