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Advected LPW product in identifying circulations in the vertical

Posted On: February 24, 2017 - By: Dan Bikos


On the evening of 21 February 2017, a well defined mid-level circulation moved into the San Francisco Bay region.  This circulation was responsible for a region of convection in the vicinity, mostly showers but a few thunderstorms with some low-level rotation.

The mid-level circulation can be readily identified in the 700-500 mb layer of the CIRA advected layer precipitable water (LPW) product (lower left panel) :

mid-level_circulation

The circulation also shows up, to a lesser extent, in the 850 – 700 mb layer (upper right panel).

A loop of the product is shown here:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/21feb17_alpw

This product consists of moisture information from microwave sensors on various polar orbiting satellites, which is then advected by a model for a very short-term forecast.  Mid-level circulations that are sufficiently large enough to be resolved can be readily observed, and also indicate where they are in the vertical, providing information about the depth of the circulation.

This product is new, building on the previous product termed the layered precipitable water product which 1) made use of lower resolution data (i.e., more blocky) and 2) did not include advection from a model.  A loop of the LPW product for this case:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/21feb17_lpw

still shows the mid-level circulation, but not nearly as well due to the more coarse resolution of the data (and perhaps due to advection not being included also).


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