Spotter Training 2004

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May 22, 2004A date that was unforgettable
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May 22, 2004A date that was unforgettable
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It does not always look like a tornado!
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It does not always look like a tornado!
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54 miles long, 2.5 miles wideF4
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Lincoln
Bennet
Hallam
Daykin
Beatrice
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The Hallam Tornado

• The storm did not look like a tornado to spotters
  and chasers. The fact that the cloud base was
  very low, the tornado circulation was very wide,
  along with the tornado being rain-wrapped at
  times, and darkness setting in made the storm
  extremely difficult to identify.

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Reporting Procedures
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What do you report ?

• Tornado or Funnel Cloud
• Wall Cloud (rotation or rapid vertical motion?)
• Hail (estimate size)
• Wind Damage (estimate speed)
• Shelf or Roll Clouds
• Flash/Urban Flooding

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HAIL SIZES

• 1/4" PEA
• 1/ 2" MARBLE ....TRY TO AVOID THIS
  DESCRIPTION
• 3/4" DIME OR PENNY
• 1" QUARTER
• 1 1/4" HALF DOLLAR
• 1 3/4" GOLFBALL
• 2 1/ 2" TENNIS BALL
• 2 3/4" BASEBALL
• 3" TEACUP
• 4" GRAPEFRUIT
• 4 1/ 2" SOFTBALL

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How do you report ?Be ready to answer the
following questions

• Who ?
• What ?
• When ? (Give time of event, not the current
  time)
• Where ? (Give location, intersection of roads,
  GPS location, etc.)
• Any damage from the event?

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How to contact NWS with a report

• Call law enforcement or dispatcher
• Use amateur radio net
• Use E-spotter
• Toll free number

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E-spotter is a NWS program that allows
spotters to email reports directly to the NWS
office. Spotter reports come directly into the
NWS AWIPS workstation and a local storm report
can be generated from these reports. To
register go to espotter.weather.gov
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Hazardous Weather Outlook

• Issued between 5 and 6 AM
• Updated between 11 AM and NOON (April-Sept.) and
  between 5 and 6 PM or when needed
• Discussion provides timing, location, coverage,
  probability and expected severity of weather

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Required Ingredients for Severe Thunderstorms

• MOISTURE
• Preferably in the lower or middle levels of the
  atmosphere
• INSTABILITY
• Ability for air to accelerate upward/downward
  when started up/down
• SOURCE OF LIFT
• Agent which lifts moist unstable air, starting
  the thunderstorm
• WIND SHEAR
• Winds that turn clockwise and/or increase in
  speed with height.

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Three Thunderstorm Stages
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Thunderstorm Classifications

• Single Cell
• Multicell Clusters
• Multicell Lines (Squall Lines)
• Supercell

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Supercell Thunderstorms
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Supercell Structure
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Radar View of Supercell
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Upper Level Storm Clues
Overshooting Top- Domelike bubble of cloud
material extending above the anvil and persisting
for gt 10 minutes
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Upper Level Storm Clues

• Anvil Characteristics
• Thick, cumuliform anvil with sharp,well-defined
  edges and backsheared

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Video of a Supercell
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Mid Level Storm Clues
A vertical and solid appearance to the main
updraft tower
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Low Level Storm Clues

• Rain-Free Base-
• Low, flat cloud base with little visible
  precipitation falling and updraft towers above
• Flanking Line -Row of towering cumulus stair-
  stepping up to main storm tower

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MESOCYCLONES

• A mesocyclone is the rotating updraft portion of
  a supercell storm.

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WALL CLOUDS
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A wall cloud is an isolated lowering of a
rain-free cloud base, usually underneath the most
intense part of the updraft, and attached to the
cloud base
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Tornado Life Cycle

• Developing stage - Circulation associated with
  the funnel cloud descends to the ground and
  intensifies. Visible funnel increases in size.
• Mature stage - Tornado reaches maximum size and
  intensity.
• Rope stage - Tornado weakens and decreases in
  size.

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Developing Tornado
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Fast Developing Tornado
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Mature Tornado
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Mature Tornado
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Rope Stage Tornado
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Tornado from Development to Rope Stage
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Other Thunderstorm Hazardsand Safety
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Lightning is the spotters most common danger!
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Damaging Winds
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Rear Flank Downdraft

• The rear flank downdraft or RFD can be very
  intense. Spotters should stay a safe distance
  from the wall cloud and tornado

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Strong or damaging winds can occur right along
the leading edge of the shelf cloud

• Photo by Marty Feely near Missouri Valley

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Scud
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WALL CLOUDS SHELF CLOUDS

• SUGGEST INFLOW/UPDRAFT
  SUGGESTDOWNDRAFT/OUTFLOW
• MAINTAIN POSITION WITH MAY
  MOVE AWAY FROM THE
• RESPECT TO THE UPDRAFT STORM
  IN THE DOWNDRAFT
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  REGION
• ROTATE ABOUT A VERTICAL MAY
  ROTATE ABOUT A
• AXIS
  HORIZONTAL AXIS

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Flash Floods
Lincoln, NE August 28, 2002
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Two unusual deaths attributed to heavy rainfall
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Make sure you pay attention to the signs
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Do not get too close!
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Avoid getting caught in the heaviest
precipitation area north of the mesocyclone or
the Bears Cage THIS AREA HAS THE LARGEST
HAIL!
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Spotter Safety

• Be alert to hazardous driving conditions like wet
  roads and poor visibility
• Avoid distractions while driving such as
  Operating radios or cell phones or watching
  storms
• Always have an escape route
• Stay in your vehicle as much as possible because
  of lightning and large hail
• Do not hide under an overpass!

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Night Spotting
Lightning illuminates cloud features or look for
flashes of light from power lines or transformers.
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Final thoughts..
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How many minutes is your county under a tornado
warning each year?
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Killer Tornadoes 1950-2003
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NATIONAL WEATHER SERVICE WEB SITE

• www.crh.noaa.gov/oax/