Diamond Lakes Area SKYWARN
Severe Weather Definitions

Enhanced Fujita Tornado Scale

65-85 mph - GALE TORNADO - Some damage to chimneys, breaks branches, pushes over shallow-rooted
                                                                  trees, damages sign boards.

     85-110 mph - MODERATE TORNADO - The lower limit is the beginning of hurricane force winds, peels
                                                                                surface off roads, mobile homes pushed off foundations or
                                                                                turned over, moving autos pushed off roads.

     111-135 mph - SIGNIFICANT TORNADO - Roofs torn off frame homes, mobile homes demolished,
                                                                                    boxcars pushed over, large trees snapped or up-rooted,
                                                                                    light-object missiles generated.

     136-165 mph - SEVERE TORNADO - Roofs and walls torn off well constructed houses,
                                                                          trains overturned, most trees in forest up-rooted, heavy cars lifted
                                                                          off the ground and thrown.

     166-200 mph - DEVASTATING TORNADO - Well constructed houses leveled, structures with weak
                                                                                       foundations blown off some distance, cars thrown,
                                                                                       large missiles generated.

     Over 200 mph - INCREDIBLE TORNADO - Strong frame houses lifted off of foundations and carried
                                                                                    considerable distance to disintegrate, automobile sized
                                                                                    missiles fly through the air in excess of 100 meters, trees
                                                                                    debarked, incredible phenomena will occur.

*** Important note about Enhanced F-Scale Winds: The Enhanced F-Scale is STILL a set of 'wind estimates',
NOT measurements, based on damage.
It uses three-second gusts estimated at the point of damage, based on
a judgement of 8 levels of damage to the 28 indicators listed below. These estimates vary with height and exposure.
Important: The 3 second gust is not the same wind as in standard surface observations. Standard measurements are
taken by weather stations in open exposures, using a direct measured, 'one minute mile' speed.

*** See EF Scale Information at the Storm Prediction Center's Website .

Descriptive Terms For Hail

Graupel (not true hail, also called snow pellets)
1/4"     Pea
1/2"     Mothball
3/4"     Dime
7/8"     Nickel
1"        Quarter
1-1/4"  Half dollar
1-1/2"  Ping-Pong Ball / Walnut
1-3/4"  Golf Ball
2"        Hens Egg
2-1/2"  Tennis Ball
3"        Tea Cup
4"        Grapefruit
4-1/2"  Soft Ball

NOTE:  The NWS would prefer that hail size be reported by actual measured size. Reports should give the
               maximum dimension of the largest stone found. If there is very large variation in size, indicate the
               largest found and the typical size.

Modified Beaufort Scale of Wind Effects

<1 mph         
Calm, smoke rises vertically.
1-3 mph         Weather vanes stationary, smoke shows wind direction.
4-7 mph         Wind felt on face, leaves rustle, wind vane begins to move.
8-12 mph       Leaves and small twigs in motion, wind extends a light flag.
13-18 mph     Wind raises dust and loose papers, small branches move.
19-24 mph     Small trees with leaves begin to sway, crested wavelets on inland waters.
25-31 mph     Large branches move, wires whistle, umbrella becomes difficult to control.
32-38 mph     Whole trees sway, resistance felt walking into the wind, trash cans blown away.
39-46 mph     Twigs break off trees, cars may veer off road.
47-54 mph     Slight structural damagemay occur (shingles blown away), tall grasses laid flat by wind.
55-63 mph     Shallow rooted trees blown over, difficult to breathe facing into wind.
64-72 mph     Breaks branches off trees, damages signs, some windows blown out.
73-112 mph and Above     See Fujita Tornado Scale above.

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