Thursday, June 18, 2015

Lake Breeze Front moving up Salt Lake Valley

Differential heating of water and land surfaces often causes a pressure gradient to set up between the Great Salt Lake and the surrounding land. This pressure gradient causes winds to blow from the lake to the land on hot clear days like today. From the MesoWest observations shown below you can see the surface winds blow north from the lake. Winds near Draper and Bluffdale, however, are from the south. The lake breeze front hasn't reached that far south at the time this screen shot was taken (7:45 PM)

Doppler radars are used for much more than just tracking rain. We can also how fast the winds are blowing. Below is the radial velocity. That means we measure the speed of objects relative to the radar. A negative value is wind blowing toward the radar, a positive value means wind is blowing away from the radar. Below, the green colors are moving toward the radar (white + north of North Salt Lake) and yellow is moving away form the radar. You can see the lake breeze fill in the Salt Lake valley over time as the winds switch from blowing toward the radar to blowing away from the radar. Also note...this radar is not the National Weather Services' Radar on Promontory Point. This is the TDWR Radar operated by the airport used for aviation and is especially useful for detecting microburst winds during thunderstorms. Since the radar is at ground level it can measure winds closer to the surface. However, there is much more interference from ground clutter and blocking from mountains.

I recently downloaded the raw radar data and plotted it up in IDV. Here is the finished product...

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