Pennsylvania, 1999

Damaging Wind in Pennsylvania, August 14, 1999

August 14, 1999 · NWS PHI · 1 event in 1 county or zone

A microburst associated with a severe thunderstorm caused concentrated wind damage on Long Lane in Horsham Township. Eleven trees were knocked down on one property, some were 80 years old.

Where it happened

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The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS PHI wrote it up.

A microburst associated with a severe thunderstorm caused concentrated wind damage on Long Lane in Horsham Township. Eleven trees were knocked down on one property, some were 80 years old. The thunderstorm blew an air conditioner on another property into the house and tossed a second one onto the lawn. A trampoline and swing set were crushed. PECO Energy reported about 47,000 homes and businesses lost power in southeast Pennsylvania. Most of the outages were in the surrounding suburbs of Philadelphia. About a quarter of the outages were attributed to the wind. There were about 1,600 cloud-to-ground lightning strikes as the thunderstorms moved through Southeast Pennsylvania during the late afternoon of the 14th. The storms overnight produced about 5,000 cloud-to-ground strikes.

The radar

The Philadelphia radar (KDIX), 68 km away, was scanning. The volume nearest the first event began at 21:26 UTC.

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Event by event

1 thunderstorm wind. Local standard time, as filed.

Thunderstorm Wind, Montgomery

When
August 14, 4:25 PM EST
Where
Montgomery County, Horsham
Reported by
NEWSPAPER
Coordinates
40.180, -75.150

What these are

Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Pennsylvania in 1999Every state in 1999This day in weather historyWarnings in Pennsylvania, August 1999

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5717992.