STORM2K

Gustnado produced damage in largo Wednesday evening...

Observations from local residents combined with NWS Doppler radar
data confirm that the wind damage in largo was the result of a
gustnado. The preliminary event time was close to 605 PM EDT.

A gustnado is a small tornado that forms on the leading edge of a
thunderstorm gust front. While most gust fronts typically produce a
straight line cooling wind... sometimes multiple gust fronts... also
known as outflows... can collide from different directions. If the
collision occurs at just the right angle... rotation can develop
along the leading edge of the dominant storm.

At least two boundaries were visible on radar early Wednesday
evening... one nearly stationary (the Gulf Coast sea breeze) just
onshore of western Pinellas County and another moving from southeast
to northwest from Saint Petersburg toward largo... Clearwater... and
the central Pinellas beaches.

When the outflow from the primary storm moving through central and
southern Pinellas County reached the nearly stationary sea breeze
boundary near largo... the gustnado formed.

An NWS survey team is currently investigating the damage. An
updated statement... including estimated wind speeds... track
path... and start and end time... will be issued later this afternoon.

Gustnado. What exactly is a gustnado? I know it's a type of tornado but what sets it apart?

It's formed along the leading edge of a gust front...along a line of thunderstorms or at intersecting gust fronts and/or thunderstorms. It's not formed from a mesocyclone like most other tornadoes (including supercell and comma head tornadoes) are.

they look like they form from the ground up