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Spotter Guide

SKYWARN OBSERVER'S GUIDE
REVISED 11/25/06

When acting as a spotter, always remember that YOUR SAFETY IS MOST IMPORTANT! During a thunderstorm with lightning, stay in your covered vehicle with the windows up and door shut.

DO NOT TRY TO OUTRUN A TORNADO IN YOUR CAR! Get out of your car and curl up into a ball in a ditch or ravine in a location that will be as free of flying debris as you can, but be aware of localized flooding. Keep your head covered and eyes closed.

Above all else, use common sense and DON'T TAKE UNNECESSARY RISKS!

NEVER place yourself in any danger when reporting Severe Weather!
We need you, and thank you for your help!

Please include the following items in all your SKYWARN reports:

WHO: Identify yourself "SKYWARN Spotter" (name plus callsign if amateur radio operator)

WHERE: Report your county and state, and position relative to a known town/landmark ("Seven miles west of Galax"). If the event is not occurring where you are, report your position relative to the event/storm ("Looking three miles north of my location"). If applicable, report the movement and speed of the event being observed.

WHAT: Describe the event/storm (see reporting criteria below)

WHEN: Report the exact time of the event/storm, duration of the event, and if the event still in progress.

WHAT TO REPORT

ONLY REPORT OBSERVATIONS, NOT INTERPRETATIONS

• Funnel Clouds
• Tornadoes
• Wall Clouds (confirmed or suspected)
• Mama Clouds (mammatus)
• Roll Clouds
• Shelf Clouds
• Report ANY KIND of Thunderstorm Activity During the Winter Months
  • Report time of observation
  • Location
  • Direction of movement

• Downburst Winds
• Wind Damage to Buildings
• Wind Damage to Trees (large limbs broken off)
• Wind Speeds of 35 mph or Greater
• In Non-Thunderstorm Events, Report Winds in Excess of 50 mph or Greater
  • Report time of observation
  • Location
  • Estimated wind speed
  • Estimated wind direction

• Hailstones of Any Size (initial report)
  • Report time of observation
  • Location
  • Size of hailstones - Measure if possible, report largest size, most common size, and depth of coverage. For size reference, use the following table:
     

  HAIL DIAMETER	DESCRIPTION	HAIL DIAMETER	DESCRIPTION
  1/2"	Dime Size	3/4" (Severe Criteria)	Penny Size
  7/8"	Nickel Size	1"	Quarter Size
  1 1/4"	Half Dollar Size	1 1/2"	Walnut or Ping Pong Ball Size
  1 3/4"	Golf Ball Size	2"	Hen Egg Size
  2 1/2"	Tennis Ball Size	Or Report Actual Measurement

• Lightning Strikes to People
• Lightning Strikes to Animals
• Lightning Strikes Causing Building Damage
  • Report time of strike
  • Location
  • What was struck

• Flooded Streets
• Standing Water in Buildings
• Water Over the Banks of Creeks and Streams
• Rainfall Rates of One (1) Inch Per Hour or Greater
  • Report time of observation
  • Location
  • Depth of standing water (if possible)
  • Actual rainfall rate (if possible)
  • Rainfall totals at the end of a storm event

• Snow Accumulation of Three (3) Inches - Snowfall Rates of One (1) Inch Per Hour - or Greater
  • Report time of observation
  • Location
  • Depth of snow
  • Actual snowfall rate (if possible)
  • Snowfall totals at the end of a storm event

• Icing
  • Report any ice accumulation
  • Time of observation
  • Location
  • Measure or estimate thickness of accumulation
  • Damage reports

  Visit NWS Blacksburg's Winter Weather Reporting Procedures page for more information.

• Weather-related Personal Injury
  • Advise Local Law Enforcement FIRST!
  • Report what person was doing, age, sex, and cause of injury.

• Any Other Pertinent Reports that may be regarded as a Threat to Life and Property, including power outages.

ALWAYS Record and Report the TIME & LOCATION of Your Observation

ALWAYS IDENTIFY YOURSELF AS A SKYWARN SPOTTER

If a SKYWARN net has been ACTIVATED in your County, report observations to your Net Control Station.

If a SKYWARN net has NOT been activated in your area, report observations by phone to your local emergency management office, law enforcement agency, or the National Weather Service.

The General Public should contact their local emergency management or law enforcement agency during times of severe weather, NOT the National Weather Service.

Notes

When spotting for WALL CLOUDS, FUNNEL CLOUDS, and TORNADOES, the key is always to LOOK FOR ROTATION! Often, scud clouds are mistaken for funnels or tornadoes because they may form beneath the parent thunderstorm and appear to touch the ground. Just remember... with scud there will be no rotation.

When estimating WIND SPEED feel free to use the Beaufort Wind Scale provided in this guide (complete chart below). Study the description of the Effects Observed and choose the appropriate wind speed range from the table. Report the speed in miles per hour or in knots. Do not report the Beaufort Force Number. This will likely send the meteorologists at the National Weather Service scurrying for reference books, wasting valuable time.

ESTIMATING WIND SPEED
25-31 - Large branches moving. Whistling in overhead wires.
32-38 - Whole trees moving. Inconvenience in walking against wind.
39-46 - Small branches (twigs) break. Impedes walking.
46-54 - Slight structural damage. Larger branches, and weak limbs may break.
55-63 - Moderate structural and tree damage.
64 and above - Heavy to severe tree, and structural damage.

When reporting WIND DIRECTION remember that it is ALWAYS the direction the wind is blowing FROM. For example, if you report the winds as Southerly at 10 mph, that means the winds are coming from the south, blowing to the north.

When reporting HAIL, use the common references that are used by the National Weather Service, ranging from dime size (1/2 inch) to softball size (4 1/2 inch)... arggghhhh... let’s hope you never have to report that!!! See the handy hail size table above.

When assessing WIND DAMAGE, remember that most wind damage is done by straight-line winds, not by tornadoes. With straight-line wind damage, all the damage will look like it diverges (moves outwards) from a single point possibly in several directions. With tornado damage, destruction is generally along one direction, debris along the ground is twisted or has spiral characteristics, and often small arcs where the top-soil has been removed are visible.

IF A PERSON IS STRUCK BY LIGHTNING, TAKE APPROPRIATE ACTION TO ENSURE IMMEDIATE AID IS GIVEN! A person retains no electrical charge after being struck, so it is safe to touch that person. This means CPR can be administered immediately if necessary. REPORT the occurrence to LOCAL LAW ENFORCEMENT as soon as possible!

SPOTTER RULES AND CLUES

1. Always have a safe place nearby to protect yourself from wind and/or hail.
2. Cars are a safe place from lightning, but NOT from tornadoes.
3. Moving water is powerful, it only takes a slight current to push a vehicle off the road.
4. Overshooting tops are an indicator of a very strong storm.
5. The first gust of wind to reach you from a thunderstorm is frequently the strongest.
6. A rain free base denotes the storm's updraft area, a place to watch closely.
7. WALL CLOUDS form on the rain free base often 15 to 20 minutes before the tornado occurs.
8. Large hail often falls just in advance of a tornado, especially large tornadoes.
9. Tornadoes usually form in the trailing edge of a thunderstorm.
10. TORNADOES generally move toward the NORTHEAST at 25 to 35 MPH when associated with fronts, and squall lines but CAN travel as fast as 70 MPH.

THE SPOTTER'S OBSERVATION KIT

Consider keeping the following equipment handy:

• WEATHER RADIO (It’s nice to be able to keep up with weather warnings.)
• COMMUNICATIONS RADIO for reporting your observations (When you see severe weather, you’ve got to report it!)
• RAINCOAT WITH HOOD (Stay dry!)
• FLASHLIGHT (In case you can’t see when it gets dark!)
• BINOCULARS (So you can tell whether that cloud is really rotating!)
• CAMERA or CAMCORDER (So that a permanent record can be made of your observations. Pictures and video are the BEST form of training for other spotters.)
• COMPASS (For estimating the wind direction -- remember, that’s the direction the wind is coming from!)
• Your SKYWARN OBSERVER'S GUIDE (So you can remember all this stuff!)

	At 300mb, a strong jet stream aids in both increasing the wind shear and divergence. This divergence pulls air out of the column and intensifies the surface cyclone, which in turn strengthens the flow around the Low and makes the fronts stronger.
	A trough enhances lifting in the mid to upper levels. Think of the trough at 500mb as another lifting mechanism.
	Cold dry air from the southwest helps to further increase the wind shear and destabilizes the sounding by making the environment cold in the mid levels. That means that a parcel lifted from the surface will most likely be warmer than the environment and continues to rise on its own.
	The low level jet enhances the vertical wind shear (both in speed and direction). Wind shear is a VITAL ingredient in producing rotating thunderstorms. This warm moist air also supports an unstable sounding (warm and moist in the lower levels, cold and dry in the upper levels.
	Strong surface cyclone sets up the best environment to get the three ingredients necessary to produce thunderstorms. Well-defined fronts provide a surface lifting mechanism. Surface convergence toward the center of the Low draws warm moist unstable air from the south.

The Beaufort Scale is the oldest method of judging wind force, since it was proposed by Admiral Sir Francis Beaufort in 1806. Separate scales for tornadoes and hurricanes did not come until the 1970's.