Friday, March 20, 2009
The "Weak" Front
OK...that turned out not to be such a weak front. There was no indication in the models we would have such a sharp transition and with no coastal radar we could not see it coming. A convective line formed on the front with very heavy precipitation...take a look at the radar..you can see the reddish color of very intense precipitation. The observations at the top of the UW Atmos. Sci building shows the dramatic nature of the transition...substantial wind shift, sharp pressure trough, sudden drop of temperature and increase of humidity, and increase in winds to 30 mph (see figure). Or look at the Seattle profiler (image)...a very sharp shift from southerly to SW winds and big temp decline. Finally, you can see the line in the visible satellite imagery if you look carefully (image).
Posted by Cliff Mass at 9:53 PM