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Severe Weather Outbreak
4 August 2004

Six (perhaps seven) different locations in the Harrisburg Area had tornado damage (rated up to F1 strength) on the evening of August 4th, 2004. Four of these locations were within 15 miles of Downtown Harrisburg.

Six (possibly seven) locations in the lower Susquehanna Valley had tornado damage on the evening of August 4th, 2004.
 
Despite the fact that these tornadoes happened during the evening rush hour (between 5 and 7 PM EDT) and hit one of the most heavily-populated areas in Central Pennsylvania, NO deaths NOR even injuries were attributed to these storms!
 
Reasons for this may include the high level of attention given to the storms and tornado warnings by the local news media, coupled with the fact that many area residents had fresh in their minds a recent F3 tornado in Campbelltown, Lebanon County. The residents may have taken protective action based on the warnings, due to their recent reminder of the destructive potential of a tornado's fast winds.
 
5 of these 6 locations (labelled #2 through #6 on the map below) may have received damage from the same thunderstorm cell that may have produced multiple tornadoes during it's lifetime. This is also known as a family of tornadoes. Radar images of that cell can be seen below.
 
The first location to receive damage was just north of the Turnpike between Carlisle and Newville, Cumberland County (labelled as 10W Carlisle, Location #1). This tornado likely came out of a thunderstorm cell that was not the cell that most likely spawned the other five tornadoes.
 
The next location to receive tornado damage was the city of Lemoyne, just west of the City of Harrisburg (labelled Location #2). This was the first damage from the cell that most likely spawned the tornadoes that made damage at the next 4 locations, as well.
 
The main rotation of the storm cell that hit Lemoyne then moved to the east and then southeast. As it did so, damage occurred in Harrisburg, Swatara and Derry Townships (Dauphin County), and finally just northwest of Manheim (Lancaster County).
 
A seventh location of a possible tornado touchdown is currently under investigation, in Southeastern York County, near Felton. See corresponding radar pics: Reflectivity, SRM. Around 7:05 PM, a storm spotter in Felton snapped pictures of a funnel cloud that may have extended below tree-tops. It is unknown if damage occurred in that location, as this report was not available until after the storm damage surveys of the other sites had been completed.

 
map of damage locations See close-up map of this area See close-up map of this area See close-up map of this area See close-up map of this area See close-up map of this area See close-up map of this area

Radar images of the storms:

4-panel views of Reflectivity, SRM, Composite Refl and IR Sat Pics around the time of damage
at location #1 (10W Carlisle), #2 (Lemoyne), #4 (Swatara Twp), #5 (Derry Twp), #6 (near Manheim).

  • KLWX 0.5 deg Reflectivity and Storm Relative Motion (SRM) at 2201Z (6:01 PM).
  • KLWX Reflectivity Loop 2131Z to 2302Z (5:31 PM to 7:02 PM). (517 KB)
  • KCCX 4-panel Reflectivity, SRM at 2212Z (6:12 PM).
  • KCCX 4-panel Reflectivity, SRM at 2216Z (6:16 PM).
  • KCCX Base Velocity Loop 2132Z to 2303Z (5:32 PM to 7:03 PM). (638 KB)
  • Satellite Imagery:

    Visible Satellite Loop 21:32Z to 23:15Z (5:32 PM to 7:15 PM). (~2MB)

    Damage Photos:

    Pictures of damage across Cumberland, Dauphin, and Lancaster Counties.
    Pictures of damage near Manheim (#6): Trees and Corn, Corn Blowdown, Trees Snapped
    Funnel cloud observed over Felton, York County at 23:05Z (7:05 pm).

    Related Text Products:

    Public Information Statement issued after the Surveys were completed Thursday Evening:

    NOUS41 KCTP 052335
    PNSCTP
    
    PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-049>053-
    056>059-063>066-061600-
    
    PUBLIC INFORMATION STATEMENT
    NATIONAL WEATHER SERVICE STATE COLLEGE PA
    732 PM EDT THU AUG 5 2004
    
    ...F1 TORNADO CONFIRMED IN CUMBERLAND...DAUPHIN AND LANCASTER
    COUNTIES...
    
    TWO SURVEY TEAMS SENT BY THE NATIONAL WEATHER SERVICE IN STATE
    COLLEGE CONFIRMED TODAY THAT SEVERE THUNDERSTORMS SPAWNED AN F1
    TORNADO THAT TOUCHED DOWN IN MULTIPLE LOCATIONS IN
    CUMBERLAND...DAUPHIN AND LANCASTER COUNTIES DURING THE EARLY EVENING
    OF WEDNESDAY AUGUST 4. THE SURVEY TEAMS WERE EXTENSIVELY ASSISTED BY
    THE CUMBERLAND...DAUPHIN AND LANCASTER EMERGENCY MANAGEMENT
    AGENCIES...AS WELL AS THE CITY OF HARRISBURG.
    
    THE TORNADO FIRST TOUCHED DOWN NORTHEAST OF NEWVILLE IN CUMBERLAND
    COUNTY...WHERE DAMAGE WAS INITIALLY REPORTED. THE NEXT TOUCHDOWN
    OCCURRED IN CUMBERLAND COUNTY JUST EAST OF CAMP HILL IN LEMOYNE. THE
    TORNADO THEN WENT THROUGH SWATARA TOWNSHIP DAUPHIN COUNTY NEAR ROUTE 
    322...AND AT ANOTHER LOCATION NEAR CLIFTON.
    
    THE LAST LOCATION THE TORNADO TOUCHED DOWN WAS JUST NORTHWEST OF 
    MANHEIM IN LANCASTER COUNTY. DAMAGE TO HOUSES AND TREES WERE FOUND IN
    ALL OF THESE LOCATIONS. 
    
    THE DISTANCE BETWEEN THE BEGINNING AND END POINTS OF DAMAGE
    ASSOCIATED WITH THE TORNADO WAS 77 MILES...HOWEVER THE TORNADO WAS
    ESTIMATED TO BE ON THE GROUND FOR A TOTAL OF 5 TO 7 MILES WITH
    SPORADIC MULTIPLE TOUCHDOWNS.
    
    THE WIDTH OF THE TORNADO WAS 50 YARDS AT ITS NARROWEST POINT...AND
    GREW TO ONE QUARTER MILE AT ITS WIDEST. IN ALL...DOZENS OF HOMES
    WERE DAMAGED...MOSTLY AS A RESULT OF TREES FALLING ON THEM. HUNDREDS
    OF TREES WERE KNOCKED DOWN THROUGHOUT THE AREA. FORTUNATELY NO
    INJURIES OR FATALITIES OCCURRED IN ALL THREE COUNTIES.
    
    WINDS WERE ESTIMATED BETWEEN 80 AND 90 MPH...PUTTING THIS INTO THE F1
    CATEGORY ON THE FUJITA SCALE. FOR REFERENCE:
    
    F0 - 40 TO 72 MPH WINDS
    F1 - 73 TO 112 MPH WINDS
    F2 - 113 TO 157 MPH WINDS
    F3 - 158 TO 206 MPH WINDS
    F4 - 207 TO 260 MPH WINDS
    F5 - 261 TO 318 MPH WINDS 
    

    The initial damage reports from that evening follow:

    NWUS51 KCTP 050202
    LSRCTP
    
    PRELIMINARY LOCAL STORM REPORT ... SUMMARY
    NATIONAL WEATHER SERVICE STATE COLLEGE PA
    1001 PM EDT WED AUG 04 2004
    
    ..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
    ..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
                ..REMARKS..
    
    0300 PM     TSTM WND DMG     10 SW CURWENSVILLE      40.87N 78.65W 
    08/04/2004                   CLEARFIELD         PA   EMERGENCY MNGR  
    
                LARGE TREE DOWN
    
    0400 PM     TSTM WND DMG     JOHNSTOWN               40.33N 78.92W 
    08/04/2004                   CAMBRIA            PA   EMERGENCY MNGR  
    
                TREES AND WIRES DOWN
    
    0410 PM     TSTM WND DMG     SNOW SHOE               41.03N 77.95W 
    08/04/2004                   CENTRE             PA   LAW ENFORCEMENT 
    
                TREES DOWN
    
    0430 PM     TSTM WND DMG     5 W OSTERBURG           40.18N 78.62W 
    08/04/2004                   BEDFORD            PA   LAW ENFORCEMENT 
    
                TELEPHONE POLE AND WIRES DOWN
    
    0615 PM     TSTM WND DMG     CARLISLE                40.20N 77.20W 
    08/04/2004                   CUMBERLAND         PA   BROADCAST MEDIA 
    
                SEVERAL TREES DOWN ALONG BELVEDERE AVENUE
    
    0620 PM     TSTM WND DMG     HARRISBURG              40.28N 76.88W 
    08/04/2004                   DAUPHIN            PA   BROADCAST MEDIA 
    
                SEVERAL TREES DOWN ON 14TH AND MARKET STREET...ALSO ON 
                FRONT STREET.
    
    0620 PM     FLASH FLOOD      YORK                    39.96N 76.73W 
    08/04/2004                   YORK               PA   TRAINED SPOTTER 
    
                SEVERAL ROADS FLOODED COUNTY WIDE
    
    0620 PM     TSTM WND DMG     NEWVILLE                40.17N 77.40W 
    08/04/2004                   CUMBERLAND         PA   BROADCAST MEDIA 
    
                STRUCTORAL DAMAGE
    
    0628 PM     TSTM WND DMG     1 N COLONIAL PARK       40.31N 76.81W 
    08/04/2004                   DAUPHIN            PA   TRAINED SPOTTER 
    
                SEVERAL TREES DOWN AT INTERSECTION OF HIGHWAY 322 AND 
                HIGHWAY 83
    
    0630 PM     TSTM WND DMG     7 SE NEW CUMBERLAND     40.16N 76.78W 
    08/04/2004                   YORK               PA   BROADCAST MEDIA 
    
                STRUCTURAL DAMAGE SHEEPBRIDGE ROAD...POTENTIAL TORNADO
    
    0655 PM     TSTM WND DMG     LITITZ                  40.15N 76.31W 
    08/04/2004                   LANCASTER          PA   LAW ENFORCEMENT 
    
                SEVERAL TREES DOWN AND WIRES DOWN.
    
    0658 PM     TSTM WND DMG     2 N WAYNESBORO          39.78N 77.58W 
    08/04/2004                   FRANKLIN           PA   LAW ENFORCEMENT 
    
                SEVERAL TREES DOWN IN MT. JOY
    
    0700 PM     TSTM WND DMG     YORK                    39.96N 76.73W 
    08/04/2004                   YORK               PA   LAW ENFORCEMENT 
    
                SEVERAL TREES DOWN THROUGHOUT COUNTY.
    
    


     
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