Thursday, January 21, 2010

Weather in Lawson Valley...

The NOAA weather forecasts for yesterday were rather intimidating – up to 6 inches of rain, gusty winds to 60 MPH, possible thunderstorms with inch-diameter hail...yikes!  But we had none of that, though the weather has been interesting nonetheless.

First, the rain.  As I write this, we're at 2.4 inches (62mm) for the three-day storm (see the top graph at right, click to enlarge).  More is definitely coming, today and tomorrow.  As you can see from the graph, we had a couple brief periods of heavy rain, and then last night a long, steady, slow accumulation.

The barometric pressure is falling very quickly as I write this, indicating a storm front is passing through (see graph at left, click to enlarge).  You can also see the two downward blips from the earlier waves in this storm.  The pressure at the moment is the second-lowest I've recorded in over 7 years of data collection.  The record-holder occurred just last month, concurrent with the heavy rains we received then.

Finally, here's the NOAA radar from just a few minutes ago (at right, click to enlarge).  The scale at the left of the chart shows intensity of rain vs. color.  We don't often see large areas of “heavy” rainfall on our doppler radars, but in this series of storms these areas have been commonplace.  Yesterday there were some smaller areas trending toward the purple of “extreme” rainfall rates, but I forgot to take a snapshot of them.  Watching these radar images over time one can visualize the path that the storm cells are taking; for this storm, the cells moved from the WNW to the ESE.  Most of the intensity seemed to be knocked out of them by the time they reached Lawson Valley (which is indicated on the radar display by a circled plus sign to the right of the words “San Diego”).

I wonder what we'll see over the next couple of days?

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