<s>
The	O
bounded	B-Algorithm
weak	I-Algorithm
echo	I-Algorithm
region	I-Algorithm
,	O
also	O
known	O
as	O
a	O
BWER	B-Algorithm
or	O
a	O
vault	O
,	O
is	O
a	O
radar	B-Application
signature	O
within	O
a	O
thunderstorm	O
characterized	O
by	O
a	O
local	O
minimum	O
in	O
radar	B-Application
reflectivity	O
at	O
low	O
levels	O
which	O
extends	O
upward	O
into	O
,	O
and	O
is	O
surrounded	O
by	O
,	O
higher	O
reflectivities	O
aloft	O
.	O
</s>
<s>
The	O
BWER	B-Algorithm
has	O
been	O
noted	O
on	O
radar	B-Application
imagery	O
of	O
severe	O
thunderstorms	O
since	O
1973	O
and	O
has	O
a	O
lightning	B-Architecture
detection	O
system	O
equivalent	O
known	O
as	O
a	O
lightning	B-Architecture
hole	O
.	O
</s>
<s>
thumb|right|BWER	O
associated	O
with	O
a	O
tornadic	O
supercell	O
in	O
2006	O
,	O
as	O
seen	O
from	O
different	O
elevation	O
angles	O
.	O
</s>
<s>
The	O
BWER	B-Algorithm
is	O
a	O
nearly	O
vertical	O
channel	O
of	O
weak	O
radar	B-Application
echo	O
,	O
surrounded	O
on	O
the	O
sides	O
and	O
top	O
by	O
significantly	O
stronger	O
echoes	O
.	O
</s>
<s>
The	O
BWER	B-Algorithm
,	O
sometimes	O
called	O
a	O
vault	O
,	O
is	O
related	O
to	O
the	O
strong	O
updraft	O
in	O
a	O
severe	O
convective	O
storm	O
that	O
carries	O
newly	O
formed	O
atmospheric	O
particulates	O
,	O
called	O
hydrometeors	O
,	O
to	O
high	O
levels	O
before	O
they	O
can	O
grow	O
to	O
radar-detectable	O
sizes	O
.	O
</s>
<s>
BWERs	B-Algorithm
are	O
typically	O
found	O
at	O
mid-levels	O
of	O
convective	O
storms	O
,	O
to	O
above	O
the	O
ground	O
,	O
and	O
are	O
a	O
few	O
kilometers	O
in	O
horizontal	O
diameter	O
.	O
</s>
<s>
The	O
presence	O
of	O
a	O
BWER	B-Algorithm
has	O
been	O
part	O
of	O
a	O
method	O
to	O
diagnose	O
thunderstorm	O
strength	O
as	O
part	O
of	O
the	O
Lemon	B-Algorithm
technique	I-Algorithm
since	O
1977	O
.	O
</s>
<s>
The	O
updraft	O
strength	O
within	O
the	O
BWER	B-Algorithm
supports	O
the	O
growth	O
of	O
large	O
hailstones	O
just	O
above	O
the	O
vault	O
,	O
which	O
can	O
be	O
displaced	O
slightly	O
into	O
the	O
direction	O
of	O
motion	O
of	O
the	O
parent	O
supercell	O
storm	O
.	O
</s>
<s>
The	O
bounded	B-Algorithm
weak	I-Algorithm
echo	I-Algorithm
region	I-Algorithm
(	O
BWER	B-Algorithm
)	O
is	O
a	O
region	O
of	O
low	O
radar	B-Application
reflectivity	O
bounded	O
above	O
by	O
an	O
area	O
of	O
higher	O
radar	B-Application
reflectivity	O
which	O
shows	O
evidence	O
of	O
a	O
strong	O
updraft	O
within	O
mesocyclones	O
.	O
</s>
<s>
Radar	B-Application
analysts	O
have	O
recognized	O
this	O
phenomenon	O
since	O
at	O
least	O
1973	O
,	O
using	O
different	O
elevation	O
scans	O
.	O
</s>
<s>
Methods	O
of	O
objectively	O
corroborating	O
that	O
a	O
BWER	B-Algorithm
is	O
associated	O
with	O
a	O
mesocyclone	O
is	O
done	O
by	O
using	O
a	O
weather	B-Application
radar	I-Application
with	O
Doppler	O
effect	O
to	O
obtain	O
the	O
precipitations	O
velocities	O
.	O
</s>
<s>
This	O
have	O
been	O
available	O
operationally	O
in	O
United	O
States	O
since	O
1997	O
with	O
the	O
NEXRAD	B-Algorithm
network	O
.	O
</s>
<s>
When	O
using	O
the	O
lightning	B-Architecture
detection	O
system	O
,	O
lightning	B-Architecture
holes	O
(	O
uncovered	O
in	O
2004	O
)	O
correspond	O
to	O
where	O
a	O
BWER	B-Algorithm
would	O
be	O
seen	O
on	O
radar	B-Application
.	O
</s>
<s>
Marshall	O
Radar	B-Application
Observatory	O
of	O
McGill	O
University	O
in	O
Canada	O
to	O
locate	O
the	O
overhang	O
region	O
in	O
a	O
thunderstorm	O
by	O
the	O
late	O
1980s	O
.	O
</s>
<s>
Its	O
radar	B-Application
uses	O
24	O
angles	O
,	O
giving	O
it	O
good	O
vertical	O
resolution	O
.	O
</s>
<s>
In	O
United	O
States	O
,	O
fewer	O
scanning	O
angles	O
are	O
made	O
within	O
the	O
WSR-88D	B-Algorithm
radar	B-Application
which	O
makes	O
it	O
more	O
difficult	O
to	O
detect	O
the	O
overhang	O
.	O
</s>
<s>
Once	O
the	O
overhang	O
is	O
located	O
,	O
it	O
is	O
possible	O
to	O
make	O
a	O
cross-section	O
to	O
view	O
if	O
it	O
is	O
related	O
with	O
a	O
BWER	B-Algorithm
.	O
</s>
<s>
However	O
,	O
since	O
1997	O
algorithms	O
have	O
been	O
developed	O
by	O
the	O
National	O
Weather	O
Service	O
to	O
determine	O
regions	O
of	O
reflectivity	O
gradient	O
in	O
three	O
dimensions	O
and	O
the	O
presence	O
of	O
BWER	B-Algorithm
in	O
convection	O
.	O
</s>
<s>
The	O
development	O
of	O
a	O
pronounced	O
BWER	B-Algorithm
can	O
lead	O
to	O
tropical	O
cyclone-like	O
radar	B-Application
signatures	O
over	O
land	O
when	O
located	O
with	O
a	O
low	O
angle	O
plan	B-Algorithm
position	I-Algorithm
indicator	I-Algorithm
(	O
PPI	O
)	O
.	O
</s>
<s>
When	O
using	O
the	O
lightning	B-Architecture
detection	O
system	O
,	O
lightning	B-Architecture
holes	O
(	O
uncovered	O
in	O
2004	O
)	O
correspond	O
to	O
where	O
a	O
BWER	B-Algorithm
would	O
be	O
seen	O
on	O
radar	B-Application
.	O
</s>
