This is the NWS report on the weather we had yesterday.
INFORMATION ON JUNE 3, 2020 DERECHO...
A DERECHO, DEFINED AS A LONG-LIVED AND EXPANSIVE THUNDERSTORM WIND
COMPLEX THAT PRODUCES WIDESPREAD SWATHS OF DAMAGING AND OFTEN
SIGNIFICANT WIND GUSTS OVER A PATH GREATER THAN 240 MILES IN LENGTH,
DEVELOPED JUST SOUTHEAST OF LAKE ERIE DURING THE EARLY MORNING HOURS
OF JUNE 3, 2020.
DAMAGING WINDS IN EXCESS OF 60 MPH WERE SPORADIC
IN WESTERN AND CENTRAL PENNSYLVANIA, BUT AS THE THUNDERSTORM COMPLEX
MOVED INTO INCREASINGLY UNSTABLE AIR IN THE EASTERN PART OF THE
STATE, WIND DAMAGE REPORTS BECAME MORE NUMEROUS AND
WIDESPREAD AND OVER 250 WIND DAMAGE REPORTS WERE RECEIVED BY THIS OFFICE FROM
EMERGENCY MANAGERS, TRAINED SKYWARN SPOTTERS, AND THE GENERAL
PUBLIC.
MOST OF THESE REPORTS WERE LOCATED WITHIN A 50-MILE WIDE
SWATH EXTENDING FROM BERKS COUNTY EASTWARD TO THE PHILADELPHIA METRO
AREA, THEN FURTHER EAST TO THE OCEAN COUNTY SHORELINE IN NEW JERSEY.
WIND GUST REPORTS BETWEEN 60 AND 70 MPH WERE COMMON, WITH SOME OF
THE HIGHEST GUSTS AS FOLLOWS:
93 MPH AT BEACH HAVEN, NJ (OCEAN COUNTY),
92 MPH AT SURF CITY, NJ (OCEAN COUNTY),
83 MPH AT READING REGIONAL AIRPORT, PA (BERKS COUNTY),
76 MPH IN POTTSTOWN, PA (MONTGOMERY COUNTY),
AND 76 MPH IN BRIELLE, NJ (MONMOUTH COUNTY).
IN ADDITION TO DESTRUCTIVE WIND GUSTS, FREQUENT TO CONTINUOUS LIGHTNING
HAIL AND HEAVY DOWNPOURS WERE ALSO EXPERIENCED THROUGHOUT THE AREA.
TRAGICALLY, FOUR DEATHS WERE REPORTED IN THE NWS MOUNT HOLLY AREA OF
RESPONSIBILITY FROM THIS DERECHO. THREE FATALITIES IN MONTGOMERY
COUNTY WERE DUE DIRECTLY TO FALLING TREES, WITH THE FOURTH FATALITY
IN DELAWARE COUNTY DUE TO A HOUSE FIRE CAUSED BY AN ELECTRICAL
MALFUNCTION FROM A FALLEN TREE.
THIS IS THE HIGHEST NUMBER OF FATALITIES FROM A DERECHO EVENT IN THE AREA SINCE 1950.
BECAUSE THIS DERECHO MOVED OFF THE COAST EARLY ENOUGH IN THE DAY, THE WARM
AFTERNOON SUN WAS ABLE TO SUFFICIENTLY DESTABILIZE THE ATMOSPHERE
FOR THE FORMATION OF ANOTHER ROUND OF SEVERE THUNDERSTORMS OVER
SOME OF THE SAME AREAS WHICH EXPERIENCED THEM EARLIER IN THE DAY.
REPORTED WIND GUSTS ASSOCIATED WITH THESE LATER THUNDERSTORMS GENERALLY
RANGED BETWEEN 45 AND 65 MPH, WITH A 68 MPH WIND GUST MEASURED AT
THE PHILADELPHIA INTERNATIONAL AIRPORT AND HIGHER GUSTS REPORTED IN DELAWARE COUNTY.
THE REMAINING THUNDERSTORMS THEN MOVED OUT OF THE AREA BY 1000 PM, WHICH BROUGHT AN END TO THE DAY’S SEVERE WEATHER.
