Clyde Foster has sent me images of Mars on Feb. 21, 26 and 27.
After seeing the 27th image I finally realized that all three likely show
regional dust clouds in and around Hellas. It was the "finger"of dust on the Northern
edge of the SPC in the 2020-02-27 image that got me looking more closely at the three images.
I posted a composite of the three images in an album I created titled
"Dust storm alerts" on the Mars Observers web site. I've attached the composite image below.
These clouds may be an indication that the SPC that is now visible has started to
sublimate. Sublimation has been known to generate high-velocity
Winds. Congrats to Clyde Foster for the detailed images.

[Jim Melka,St.Louis,Missouri U.S.A.]