cloud type/formation identification

[Chip Redmond]

Noticed these clouds over the Gulf this afternoon and was wondering what they were and how they were eroding. The clouds are within the red circled area. They were eroding in the direction of the yellow arrows.

They obviously formed within a colder air mass in place over warm water. They were eroding as if a pocket of drier air was pushing in from the northwest. The location of the high pressure is just off the coast of LA which would is causing 925-700mb winds out of the southwest, the opposite direction of the clouds eroding. The clouds should be to low for the upper level pattern of westerly winds to interact with them...

I feel as if they are some form of stratocumulus, but why the erosion from the west?

Chip

 

[Jeff Duda]

Good observation, Chip. I checked a loop and found an even more distinct cloud boundary farther southeast in the Gulf extending over the Yucatan Peninsula. Winds at 925 and 850 mb, according to SPC RUC mesoanalyses, were out of the E and SE in that area, but were very light near the center of the high. There probably was some advection of cooler, drier continental air into these clouds, and perhaps there was synoptic scale downard motion since there was a bit of a ridge aloft moving east out of the Gulf. Other than that, I don't know what would cause this feature, but it sure is cool looking.

 

[Chip Redmond]

I didn't even think to look at the SPC analysis...it makes things so easy... I took a look at the archives and at the 500mb level there seemed to be weak warm air advection into the region of the dissipating clouds. Looking at it also, the high is definitely farther south than I had originally thought which likely did result in the clouds formation.

That is one thing I really enjoy doing is looking at analysis and trying to figure out how different things formed/dissapated. I think you learn the best when there are examples right there in front of you rather than just being studious with books.


Chip

 

[Matt Sellers]

They look - on satellite, anyway - very similar to stratocumulus often found over the subtropical Pacific from the California/Baja California coasts westward or west-southwestward toward Hawaii, especially during the late spring/summer months.