<s>
A	O
tornadic	B-Algorithm
vortex	I-Algorithm
signature	I-Algorithm
,	O
abbreviated	O
TVS	O
,	O
is	O
a	O
Pulse-Doppler	B-Algorithm
radar	I-Algorithm
weather	B-Application
radar	I-Application
detected	O
rotation	O
algorithm	O
that	O
indicates	O
the	O
likely	O
presence	O
of	O
a	O
strong	O
mesocyclone	O
that	O
is	O
in	O
some	O
stage	O
of	O
tornadogenesis	O
.	O
</s>
<s>
The	O
tornadic	B-Algorithm
vortex	I-Algorithm
signature	I-Algorithm
was	O
first	O
identified	O
by	O
Donald	O
W	O
.	O
Burgess	O
,	O
Leslie	O
R	O
.	O
Lemon	O
,	O
and	O
Rodger	O
A	O
.	O
</s>
<s>
The	O
National	O
Weather	O
Service	O
(	O
NWS	O
)	O
now	O
uses	O
an	O
updated	O
algorithm	O
developed	O
by	O
NSSL	O
,	O
the	O
tornado	B-Algorithm
detection	I-Algorithm
algorithm	I-Algorithm
(	O
TDA	O
)	O
based	O
on	O
data	O
from	O
its	O
WSR-88D	B-Algorithm
system	O
of	O
radars	O
.	O
</s>
<s>
The	O
conditions	O
causing	O
a	O
TVS	O
are	O
often	O
visible	O
on	O
the	O
Doppler	B-Application
weather	I-Application
radar	I-Application
storm	O
relative	O
velocity	O
(	O
SRV	O
)	O
product	O
as	O
adjacent	O
inbound	O
and	O
outbound	O
velocities	O
,	O
a	O
signature	O
known	O
as	O
a	O
velocity	O
couplet	O
or	O
"	O
gate-to-gate	O
"	O
shear	O
.	O
</s>
<s>
In	O
most	O
cases	O
,	O
the	O
TVS	O
is	O
a	O
strong	O
mesocyclone	O
aloft	O
,	O
not	O
an	O
actual	O
tornado	B-Language
,	O
although	O
the	O
presence	O
of	O
an	O
actual	O
tornado	B-Language
on	O
the	O
ground	O
can	O
occasionally	O
be	O
inferred	O
based	O
on	O
a	O
strong	O
couplet	O
in	O
concert	O
with	O
a	O
tornado	B-Language
debris	O
signature	O
(	O
TDS	O
)	O
(	O
i.e.	O
</s>
<s>
When	O
the	O
algorithm	O
is	O
tripped	O
,	O
a	O
TVS	O
icon	O
(	O
typically	O
a	O
triangle	O
representing	O
a	O
vortex	B-Application
)	O
and	O
pertinent	O
information	O
appear	O
.	O
</s>
<s>
Radar	O
analysis	O
of	O
the	O
velocity	O
couplet	O
as	O
well	O
as	O
the	O
automated	O
TVS	O
are	O
very	O
significant	O
to	O
issuing	O
tornado	B-Language
warnings	O
and	O
can	O
suggest	O
the	O
strength	O
and	O
location	O
of	O
possible	O
tornadoes	B-Language
.	O
</s>
<s>
Although	O
many	O
tornadoes	B-Language
,	O
especially	O
the	O
stronger	O
ones	O
,	O
coincide	O
with	O
a	O
TVS	O
,	O
many	O
weak	O
EF0-EF1	O
tornadoes	B-Language
can	O
and	O
do	O
occur	O
without	O
a	O
TVS	O
,	O
especially	O
if	O
they	O
are	O
not	O
produced	O
from	O
an	O
identified	O
mesocyclone	O
.	O
</s>
<s>
This	O
rotation	O
may	O
be	O
considered	O
a	O
mesovortex	O
rather	O
than	O
a	O
mesocyclone	O
but	O
these	O
do	O
produce	O
tornadoes	B-Language
and	O
damaging	O
straight-line	O
winds	O
.	O
</s>
