Leeside cold front of 10 November 2014: Blowing dust and deep-tropospheric gravity waves

A strong cold front pushed southward across the Plains during the day on November 10, 2014.  The temperature gradient across the front was quite dramatic, as seen by the surface observations at 23:00 UTC:

sfc_2300

Visible imagery from GOES-East during the afternoon hours centered over Colorado clearly showed the southward progress of the cold front as dust was being lofted at the edge of the cold front where surface winds are strongest:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/10nov14_vis&number_of_images_to_display=21

Note the rapid movement of the cold front as it moves from southeast Colorado towards northeast New Mexico as you can easily trace it by the blowing dust.

The GOES-West shortwave albedo product also clearly shows the blowing dust:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/10nov14_swa&number_of_images_to_display=12

Confirming the existence of the dust is this webcam along I-25 at Raton Pass (along the New Mexico / Colorado border):

raton_pass_405pm

Another interesting aspect of this event are the deep-tropospheric gravity waves created by the leeside cold front.  The GOES water vapor imagery shows narrow bands coincident with the cold front as it moves southward immediately to the lee of the Rockies:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/10nov14_wv&number_of_images_to_display=75

Relatively strong vertical motion exists along these narrow bands in a broad zone through the upper troposphere and into the lower stratosphere.  The resulting vertical displacements are up to 1 km, making them appear in the water vapor imagery.

Interestingly enough, the synthetic water vapor imagery from the 4-km NSSL WRF-ARW model also depicts these narrow bands associated with the leeside cold front:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/10nov14_syn_wv&number_of_images_to_display=17

The model was too slow with the leeside cold front, and this is a known model bias due to sharp inversions that exist with shallow arctic fronts.

For more information on leeside cold fronts and their appearance in water vapor imagery see:

Ralph, F.M., P.J. Neiman, and T.L. Keller, 1999:  Deep-Tropospheric Gravity Waves Created by Leeside Cold Fronts. J. Atmos. Sci., 56, 2986-3009.

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