MILWAUKEE SKYWARN Scales For Storm Spotters
HAIL SIZE ESTIMATES:
Report The Largest Size Observed And Any Hail Covering The Ground.
MEASUREMENTS:  Measure The Outside Diameter, The Longest End-To-End Axis.
1/4- 3/8"  PEA size Composite Picture
1/2"  Small Marble  
3/4"  PENNY size 
7/8"  NICKEL size 
1"  QUARTER size
1 1/4"  HALF DOLLAR size
1 1/2"  WALNUT / PING PONG BALL 
1 3/4"  GOLF BALL size
2"  LIME/Hen EGG size
2 1/2"  TENNIS BALL size
2 3/4"  BASEBALL size
3"  LARGE APPLE
4"  SOFTBALL size
4 1/2"   GRAPE FRUIT size
4 3/4 - 5"   Computer CD / DVD size
8"    U-S Record
The Hail chart applies only to the counties served by the NWS Milwaukee/Sullivan office:
Milwaukee, Racine, Kenosha, Walworth, Waukesha, Ozaukee, Sheboygan, Washington, Fond Du Lac,
Rock, Green, Lafayette, Iowa, Dane, Dodge, Columbia, Marquette, Green Lake, , Richland, Sauk.
 
 
Wind Speed Estimates
STRAIGHT LINE GUSTS
Beaufort number Description SPEED VISUAL CLUES AND DAMAGE EFFECTS

0

Calm Calm Calm wind. Smoke rises vertically with little if any drift.

1

Light Air 1 to 3 MPH Direction of wind shown by smoke drift, not by wind vanes. Little if any movement with flags. Wind barely moves tree leaves.

2

Light Breeze 4 to 7 Mph Wind felt on face. Leaves rustle and small twigs move. Ordinary wind vanes move.

3

Gentle Breeze 8 to 12 Mph Leaves and small twigs in constant motion. Wind blows up dry leaves from the ground. Flags are extended out.

4

Moderate Breeze 13 to 18 Mph Wind moves small branches. Wind raises dust and loose paper from the ground and drives them along.

5

Fresh Breeze 19 to 24 Mph Large branches and small trees in leaf begin to sway. Crested wavelets form on inland lakes and large rivers.

6

Strong Breeze 25 to 31 Mph Large branches in continuous motion. Whistling sounds heard in overhead or nearby power and telephone lines. Umbrellas used with difficulty.

7

Near Gale 32 to 38 Mph Whole trees in motion. Inconvenience felt when walking against the wind.

8

Gale 39 to 46 Mph Wind breaks twigs and small branches. Wind generally impedes walking.

9

Strong Gale 47 to 54 mph Structural damage occurs, such as chimney covers, roofing tiles blown off, and television antennas damaged. Ground is littered with many small twigs and broken branches.

10

Whole Gale 55 to 63 Mph Considerable structural damage occurs, especially on roofs. Small trees may be blown over and uprooted.

11

Storm Force 64 to 75 Mph Widespread damage occurs. Larger trees blown over and uprooted.

12

Hurricane Force over 75 Mph Severe and extensive damage. Roofs can be peeled off. Windows broken. Trees uprooted. RVs and small mobile homes overturned. Moving automobiles can be pushed off the roadways.

All references to trees are for trees with foliage. Significantly higher winds may be required to cause similar damage to trees without foliage. Also, very wet soil conditions may allow weaker winds of 30-57 MPH to uproot trees.
 
 
 

EF  Tornado Scale
EHANCED FUJITA

 EF0  =  65 to 85 Mph Winds.  Frequency: 53.5%
 (Minor damage.) Peels surface off some roofs; some damage to gutters or siding; branches broken off trees; shallow-rooted
 trees pushed over. Confirmed tornadoes with no reported damage (those that remain in open fields) are always rated EF0.

  EF1  =  86 to 110 Mph Winds.  Frequency: 31%
 
(Moderate damage.) Roofs severely stripped; mobile homes overturned or badly damaged; loss of exterior doors; windows and
 other glass broken.

 EF2 = 111 to 135 MPH Winds.  Frequency: 10.7%
 (Considerable damage.) Roofs torn off well-constructed houses; foundations of frame homes shifted; mobile homes completely
 destroyed; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.

 EF3 = 136 to 165 MPH Winds. Frequency 3.4%
 (Severe damage.)Entire stories of well-constructed houses destroyed; severe damage to large buildings such as shopping malls;
 trains overturned; trees debarked; heavy cars lifted off the ground and thrown; structures with weak foundations blown away some distance.

 EF4 = 166 to 200 MPH Winds. Frequency: 0.7%
 (Extreme damage to near-total destruction.) Well-constructed houses and whole frame houses completely leveled; cars thrown and
 small missiles generated.

 EF5 = 200+ MPH Winds.  Frequency: 0.1%
 (Total destruction.) Strong frame houses leveled off foundations and swept away; steel-reinforced concrete  structure badly damaged;
 high-rise buildings have significant structural deformation.

DAMAGE INDICATORS:  Coming.
 
 



Sperry-Piltz Ice Accumulation Index
UTILITY POWER OUTAGES

ICE DAMAGE INDEX Radial Ice
Inches
WIND
Mph
DAMAGE and IMPACT
Descriptions
0 < 0.25 < 15  Minimal risk of damage to exposed utility systems; no alerts or advisories needed for crews.
 Few outages.
1 0.10 - 0.25 15 - 25  Some isolated or localized utility interruptions are possible, typically lasting only a few hours.
 Roads and bridges may become slick and hazardous.
0.25 - 0.50 < 15
2 0.10 - 0.25 25 - 35  Scattered utility interruptions are expected, typically lasting 12 - 24 hours.
 Road and travel conditions may be extremely hazardous due to ice accumulation.
0.25 - 0.50 15 - 25
0.50 - 0.75 < 15
3 0.10 - 0.25 > = 35  Numerous utility interruptions with some damage to main feeder lines and equipment expected.
 Tree limb damage is excessive.
 Outages lasting 1 to 5 days.
0.25 - 0.50 25 - 35
0.50 - 0.75 15 - 25
0.75 - 1.00 < 15
4 0.25 - 0.50 > = 35  Prolonged and wide spread utility interruptions with extensive damage to main distribution feeder lines,
 and some high voltage transmission line/structures.

 Outages lasting 5 to 10 days.
0.50 - 0.75 25 - 35
0.75 - 1.00 15 - 25
1.00 - 1.50 < 15
5 0.50 - 0.75 > = 35  Catastrophic damage to entire exposed utility systems, including both distribution and transmission
 networks. Outages could last several weeks in some areas.
 Shelters needed.
0.75 - 1.00 > = 25
1.00 - 1.50 > = 15
> 1.50 Any
 
 
 
Hurricanes:   Coming
 
 
 
 
 
 
 
 
 
 
 

Milwaukee Area Skywarn Association Inc, Copyright 1996-2011.

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