Severe Weather
Movie showing GOES and radar animation over the same area
(southern Colorado and western Kansas) and at the same time.
Example of nighttime return flow of moisture into Texas.
Transition from moist to dry boundary layer air over West Texas
– daytime to night
Severe Thunderstorms
• This presentation on satellites and severe
thunderstorms follows is meant to address
tornado producing storms, but may be
generalized for super cell type storms.
• One should familiar with the principals
developed in the general convection
presentation.
Nowcasting requires detailed information on mesoscale thermodynamic
structure of atmosphere, cloud type and vertical wind shear
Convection and Severe Weather
Important for Nowcasting
Convection and Severe Weather
• Vertical wind shear
• Evolving instability field
• Strength of storm
produced cold pool
• Updraft strength
• Anvil characteristics
Development
Temperature structure
• Storm-environment
interaction
• Cloud top rotation
• Storm damage
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Vertical shear
– ABI (cloud motion)
– HES-IR (moisture motion)
– HES-VNIR (cloud and moisture motion)
Evolving instability field
– ABI (surface heating)
– HES-IR (instability and surface heating)
– HES-VNIR (detailed moisture field)
Cold pool production
– HES-IR
Updraft strength
– ABI (IR top temperature)
– ABI and HES-VNIR (overshooting top height)
– Above with HES-IR (updraft efficiency)
Anvil characteristics & storm environment
interaction
– ABI (growth and detailed upper level
atmospheric motion and water vapor behavior)
– HES-IR and VNIR (as ABI but with better
spectral definition)
Rotating overshooting top
– ABI and HES-VNIR
Storm damage
– HES-VNIR
Severe Thunderstorms
Note the cold
pool left behind
by the storm, as
well as
convective
tower growth.
This 4 panel
movie
illustrates the
difference
between movies
made with 1, 5,
15 and 30
minute interval
imagery.
GOES: Imager and sounder
Instability field from
GOES over severe storm
area and severe storm at
one minute interval (right)
Vorticity - On the local scale
• Convergence on preexisting vorticity
• Tilting of vorticity from one plane to
another
• Advection from one place to another
• Differential heating
• Friction
Severe Storms Like Boundaries
•Interaction along a boundary depends
on both the storm’s and boundaries
characteristics
Wichita Falls, TX tornadic storm at 2345 GMT, Apr 10, ‘79
Wichita Falls, TX tornadic storm at 0015 GMT, Apr 11, ‘79
Wichita Falls tornado (F5) approaching a subdivision where it
destroied most of the houses. Note the multiple funnel vortices.
A house, cars, gas station and nearby Trade Winds Motor Hotel
about to be destroyed in Wichita Falls.
Role of Mesoscale Convective System in
Jarrell tornadic storm development
Genesis of Jarrell tornadic storm system
Jarrell tornadic storm system – GOES
instability development
Jarrell tornadic storm system
Near tornado time
GOES & AVHRR
anvil structure
Viewing Perspective, in part
determines what we see
April 21, 1991 Tornado Outbreak
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2 km visible
1831-0030 Z
Earth Relative Motion
Main severe outbreak
across Kansas &
Oklahoma
• Note cirrus motion and
squall line development
April 21, 1991 Tornado Outbreak
• 1 km visible zoomed to ½ km
scale
• 1831-0030 Z
• Earth Relative Motion
• Across Kansas & Oklahoma
boarder
• Note cumulus flow,
overshooting tops and cirrus
motions
April 21, 1991 Tornado Outbreak
• 1 km visible zoomed to ½ km
scale
• 1841-2030 Z
• Storm Relative Motion
• Across Kansas & Oklahoma
boarder
• Note low level moist flow and
shear in cloud layer relative to
developing storms and storm
effect on low level environment
April 21, 1991 Tornado Outbreak
• 1 km visible
• 1841- 0001 Z
• Storm Relative
Motion
• Across Kansas
& Oklahoma
boarder
• Note low level
moist flow and
shear in cloud
layer relative to
developing
storms and storm
effect on low
level
environment
April 21, 1991 Tornado Outbreak
• 1 km visible
• 2026-0001 Z
• Cirrus
Relative
Motion
• Note storm
effect on
upper flow
Evolution of instability field from GOES sounder
Severe thunderstorm development across southern Minnesota.
Visible storm relative motion of Minnesota storm.
Infrared storm relative motion of Minnesota storm
Note the “capped” cumulus cloud streets ahead of the squall line
Squall line development south of previous slide area
Overshooting tops and cloud top temperature
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Different visible enhancements
1 - none, 2 - linear min to max
3 - dual stretch min to max using temperature threshold
46
Comparison of visible enhancements
top - none versus linear
bottom - linear versus dual with temperature threshold
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Different visible enhancements
4a - none, 4b - linear min to max, 4c - dual stretch min to max
using temperature threshold
48
Different characteristics of
anvils and overshooting tops
are revealed by using different
channels. Shown here are
AVHRR visible (upper left),
3.7 microns (upper right with
special enhancement across
anvil top) and 10.7 micron IR
Visible AVHRR
10.7 micron IR AVHRR
3.7 micron AVHRR
Spectral – ABI
and VIIRS like
From MODIS
Intra-satellite: simple 3
channel RGB (VIS and NIR)
Intra-satellite: 3
channel IR RGB
combination
Overshooting
Tops
What do they
mean?
Overshooting
Tops
What do they
mean?
First one minute interval images
One minute interval visible imagery
Case Study –5 May 2002
250 mb
Surface and
Stability Loop
for 15Z on
May 5, 2002
to 02Z on
May 6
VISITView Case Study
19Z CAPE
19Z 0-6 km Shear
19Z V. Shear & CAPE
19Z CAPE & 0-3 km Shear
22Z CAPE
22Z V. Shear & CAPE
19Z CAPE
22Z CAPE
19Z V. Shear & CAPE
22Z V. Shear & CAPE
Note the “capped” cumulus cloud streets ahead of the squall line
Squall line development south of previous slide area