Tornadoes

 

 

 

 

(Images:  Salisbury, PA  Tornado May 31, 1998)

 

 

    The following is a map of Pennsylvania with each county outlined.  This map is a visual representation of the number of tornadoes per square mile x 10 ^-3.  Along the bottom of the map there is a legend that describes what value each color represents, each color is an increment of 10.  From this map we can see that the southeast and western portions of the state experience the greatest number of tornado occurrences per square mile.

 

 

 

    

    The first table is a tabulation of the number of tornadoes that were recorded for each county during the 1950-2000 time period.  This data was acquired through The National Climactic Data Center which provides tallied weather events per county ranging from tornadoes, lightning, hail, floods, wind, and the like.  

 

Table 1:  A representation of the number of recorded tornadoes per county

County  # of Tornadoes 
Adams  13
Allegheny  13
Armstrong  8
Beaver  14
Bedford  7
Berks  19
Blair  3
Bradford  12
Bucks  19
Butler  14
Cambria  17
Cameron  3
Carbon  2
Centre  9
Chester  27
Clarion  6
Clearfield  8
Clinton  7
Columbia  5
Crawford  24
Cumberland  8
Dauphin  10
Delaware  6
Elk  5
Erie  15
Fayette  9
Forest  6
Franklin  8
Fulton  1
Greene  5
Huntington  9
Indiana  6
Jefferson  11
Juniata  1
Lackawanna  5
Lancaster  25
Lawrence  9
Lebanon  12
Lehigh  10
Luzerne  14
Lycoming  19
McKean  4
Mercer  12
Mifflin  4
Monroe  11
Montgomery  15
Montour  4
Northampton  11
Northumberland  8
Perry  3
Philadelphia  7
Pike  4
Potter  6
Schuylkill  12
Snyder  6
Somerset  10
Sullivan  9
Susquehanna  4
Tioga  3
Union  4
Venango  7
Warren  8
Washington  6
Wayne  2
Westmoreland  30
Wyoming  6
York  21

 

    This first chart provides a visual interpretation of the distribution of tornadoes per county.  The x-axis represents the individual counties, the y-axis is the number of tornadoes with intervals of 5.

 

 

 

 

The following image provides another visual interpretation of the distribution of tornadoes per county from 1881 until June of 2003.

 

 

 

    The second table is a representation of the Pennsylvania county populations and is included for reference for table 3 and its following chart.  These populations are valid as of the 2001 Pennsylvania census.

 

Table 2:  This table consists of the county populations  

 

PA Counties

County Populations

Adams

92,997

Allegheny

1,270,612

Armstrong

72,101

Beaver

179,871

Bedford

49,899

Berks

377,679

Blair

128,391

Bradford

62,859

Bucks

605,379

Butler

176,593

Cambria

150,726

Cameron

5,866

Carbon

59,506

Centre

135,940

Chester

443,346

Clarion

41,478

Clearfield

83,167

Clinton

37,753

Columbia

64,152

Crawford

90,046

Cumberland

215,695

Dauphin

251,316

Delaware

551,158

Elk

34,666

Erie

279,636

Fayette

147,367

Forest

4,910

Franklin

130,506

Fulton

14,314

Greene

40,492

Huntingdon

45,632

Indiana

89,108

Jefferson

45,712

Juniata

22,877

Lackawanna

211,829

Lancaster

474,601

Lawrence

94,160

Lebanon

120,963

Lehigh

314,204

Luzerne

315,754

Lycoming

118,977

McKean

45,440

Mercer

119,682

Mifflin

46,554

Monroe

144,676

Montgomery

759,953

Montour

18,281

Northampton

269,779

Northumberland

93,662

Perry

43,787

Philadelphia

1,491,812

Pike

48,507

Potter

18,154

Schuylkill

149,176

Snyder

37,720

Somerset

79,553

Sullivan

6,532

Susquehanna

42,165

Tioga

41,621

Union

41,701

Venango

57,098

Warren

43,593

Washington

203,737

Wayne

48,392

Westmoreland

368,983

Wyoming

28,055

York

386,299

    

 

        The third table is the number of tornadoes per person per county.  These numbers were reached by dividing the number of tornadoes for a particular county by that county’s population.  To keep the data uniform, five places after the decimal place were used, which required rounding in some cases.   Juniata County had the lowest number of tornadoes per person and Sullivan County had the highest number of tornado events per person. It should be noted that Juniata County had the lowest number per person because a tornado has not been recorded in the county during the 50+ year period.

 

Table 3:  This table is the number of tornadoes per person per county  

County

Tornadoes /Person/ County

Adams

0.00014

Allegheny

0.00001

Armstrong

0.00011

Beaver

0.00008

Bedford

0.00014

Berks

0.00005

Blair

0.00002

Bradford

0.00019

Bucks

0.00003

Butler

0.00008

Cambria

0.00011

Cameron

0.00051

Carbon

0.00003

Centre

0.00007

Chester

0.00006

Clarion

0.00014

Clearfield

0.00010

Clinton

0.00019

Columbia

0.00008

Crawford

0.00027

Cumberland

0.00004

Dauphin

0.00004

Delaware

0.00001

Elk

0.00014

Erie

0.00005

Fayette

0.00006

Forest

0.00122

Franklin

0.00006

Fulton

0.00007

Greene

0.00012

Huntington

0.00020

Indiana

0.00007

Jefferson

0.00024

Juniata

0.00004

Lackawanna

0.00002

Lancaster

0.00005

Lawrence

0.00010

Lebanon

0.00010

Lehigh

0.00003

Luzerne

0.00004

Lycoming

0.00016

McKean

0.00009

Mercer

0.00010

Mifflin

0.00009

Monroe

0.00008

Montgomery

0.00002

Montour

0.00022

Northampton

0.00004

Northumberland

0.00009

Perry

0.00007

Philadelphia

0.00000

Pike

0.00008

Potter

0.00033

Schuylkill

0.00008

Snyder

0.00016

Somerset

0.00013

Sullivan

0.00138

Susquehanna

0.00009

Tioga

0.00007

Union

0.00010

Venango

0.00012

Warren

0.00018

Washington

0.00003

Wayne

0.00004

Westmoreland

0.00008

Wyoming

0.00021

York

0.00005

 

 

    The second chart provides a visual interpretation of the distribution of tornadoes per person per county.  The x-axis represents the individual counties, the y-axis is the tornadoes events per person per county with intervals of 0.0002.

 

 

 

  

The third chart provides a visual interpretation of the distribution of tornadoes per building per county.  The x-axis represents the individual counties, the y-axis is the tornadoes events per person per county with intervals of 0.0002.

 

 

 

    The fourth table is a representation of the time of year that is most prone to tornadoes.  This table was made by analyzing the dates of the recorded tornadoes and tallying them. The month of July has the highest number of tornadoes with 161, though May and June have only a few less.  This can be confirmed by the fact that these months fall within the time of year where Pennsylvania receives its greatest number of thunderstorms.  It should be noted, however, that the numbers are not exact representations as the tornadoes were originally recorded by county and more than one county can experience the same tornado at one particular time.  Therefore, duplicate tornadoes for one particular day were recorded as a single tornado.

 

Table 4:  This table represents the time of year which is most prone to tornado occurrence in Pennsylvania

 

Months of Tornadoes

# of Tornadoes 

January

6

February

1

March

21

April

60

May

117

June

143

July

161

August

78

September

64

October

13

November

31

December

0

 

 

   

The fourth chart provides a visual interpretation of the time of year which is most prone to tornado occurrence in Pennsylvania.  The x-axis represents the months, the y-axis is the number of tornado events with intervals of 50.

 

 

   

    The fifth table is a representation of the time of day that is most prone to tornadoes.  Differentiation between the times of day, regarding morning, afternoon, and night, were based upon the public’s general understanding of these time brackets. Times are in 24 hours and the times of occurrence are rounded to the hour.  Each tornado event is listed below in the table by the time of their occurrence.

  

 Table 5: This table represents the time of day that is most prone to tornado events

 

PA Tornado Frequency by the Hour

 

0: 00:00

6

1:00:00

8

2:00:00

3

3:00:00

1

4:00:00

1

5:00:00

0

6:00:00

5

7:00:00

4

8:00:00

4

9:00:00

3

10:00:00

18

11:00:00

20

12:00:00

23

13:00:00

51

14:00:00

56

15:00:00

64

16:00:00

82

17:00:00

78

18:00:00

93

19:00:00

66

20:00:00

56

21:00:00

26

22:00:00

16

23:00:00

11

 

 

    The sixth table is documenting the time of day that witnesses the most tornadoes.  Due to gaps in the available data, not all time periods were accurately accounted for.  To compensate, the day was broken down into hour intervals and the number of tornado occurrences that fell within each hour time period was recorded.  This table is based upon data provided in Table 5.  Within this table, the day is broken down into early morning, morning, afternoon and evening time periods; these times were based upon the general classification of times within the general public.  The time of day that has had the highest number of tornadoes is afternoon, with 276 tornadoes. 

 

Table 6:  This table represents the time of day that that witnesses the most tornadoes

 

Tornado Frequency by Time of Day 

Early Morning                            (0: 00:00 - 6:59:00 )

24

Morning                                      ( 7:00:00-11:59:00 )

49

Afternoon                               (12:00:0- 16:59:00 )

276

Evening                                        ( 17:00:00-20:59:00 )

170

Late Evening                                ( 21:00:00-23:59:00 )

53

 

    The fifth chart provides a visual interpretation of the time of day that that witnesses the most tornadoes in Pennsylvania.  The x-axis represents the months, the y-axis is the number of tornado events with intervals of 50.