Transcript micheledodgeppt

Synoptic, Thermodynamic,
Shear Setting
May 7, 2002 Tornadic Thunderstorm in Southwestern
Kansas
Michele Blazek
May 15, 2005
Synoptic Setting – What to look for
 Warm advection
– Found through height changes and the sounding
– Moist air advection into the jet stream
 Deep layer shear
– Approximated using the difference in the wind vectors
between the surface (surface chart) and 500 mb
– Sustains the development of storm
 Low level shear – Must be strong enough even with deep layer shear to
sustain a supercell
500 mb Wind Direction/Speed
Note the area in SW Kansas
with just east of the trough in the rockies,
ageostrophic winds in
Central Kansas and significant
favorable deep layer shear 50 kt or 5.0 E-3 /s
500 mb Chart 00 UTC 08 May 2002, Observations
Heights, Temperatures
Mesoscale Surface Chart
Note location just east
of the low and dryline
and just north of the
area of warm, wet
advection
Satellite Imagery – what to look for
 Presence of Cumuloform formations especially cumulonimbus anvils (CBA)
 Continued development of these anvils
Visible Satellite
• Note the
overshooting
cumulonimbus
anvils in
Central Kansas
2145 UTC 07 May 2002 Visible
Image UCAR
Visible Satellite - Kansas
• Note the
developing
overshooting
cumulonimbus
anvil expanding
from S Central
Kansas to the
Northeast of the
State
2315 UTC 07 May 2002 Visible Image UCAR
Thermodynamics – what to look for
 Presence of CAPE
 Possibility of CAPE developing throughout
the day
 Advection of high dew-point air north to the
jet stream
 Winds directions and shear
Shear – what to look for
 Hodograph
– Shape of hodograph - curved hodograph - possible
supercell
– Storm Relative Helicity spin due to vertical shear
(curved hodograph)
 SREH > 150 tornadoes
 SREH> 250 F2, F3
– Storm Motion
 Shear
– Deep Layer 0-6 Km (500 mb)
Greater than 35 hts and right angles to winds at 18,000
ft - favorable to midlevel mesocyclone development
– Shallow Layer
Topeka Sounding
Note the curving
Hodograph
Indicates
Storm relative
Helicity from
0-3 km!
Note
Huge shear
69 kt - 6.9 E-3/s
And helicity
0-1 km 445 m2/s2
0-3 km 690 m2/s2
Shotgun Sounding – Significant CAPE as
As day progresses!
Oklahoma City Sounding
Significant CAPE
The shape of
the
hodograph
suggests
some SREH.
Note the CAPE
of over 4000
J/kg.
The deep shear
is 49 kt. - 4.9E3/s. Low level
shear is smaller
than Topeka.
Radar Reflectivity
Look at the
hook!
Note the supercell on radar and the split from 6:47 to 7:07 pm near
Dodge City, May 7, 2002