Tuesday, September 29, 2009
An Active Convergence Zone
There was lightning and heavy rain in central Puget Sound tonight due to a strong Puget Sound convergence zone--the radar says it all (see image, yellow is heavy rain).
I watched the zone late this afternoon at the UW. Dark ominous clouds moved in from the north and a particularly dark line--associated with a shift from southerly to northerly winds--approached. Beyond the shift pouring rain was evident. Take a look at the dramatic passage at the UW (image)--large wind shift, a plummeting of the temperature, a jump in pressure as the line reached the instruments. And over a third of an inch of rain.
The high-resolution computer model (the WRF model) ran at the UW earlier in the day predicted the convergence zone formation (see image). Not perfect, but an indication of how far we have come in the last ten years or so. Certainly, meteorologists have bragging rights over their economist friends.
Posted by Cliff Mass at 9:48 PM