Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 34, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 20, 2026, 4:29 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania. It was in force for 46 min. 18 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- May 20, 2026, 4:29 PM EDT (20:29 UTC)
- Expired
- May 20, 2026, 5:15 PM EDT
- In force
- 46 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Berks County, PA, Chester County, PA, Montgomery County, PA
The radar
The Philadelphia radar (KDIX), 116 km from the middle of the area, began a volume at 20:30 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| May 20, 4:30 PM EDT | TSTM WND DMG | Birdsboro, PA | Trees down on wires. Time estimated from radar. |
| May 20, 4:30 PM EDT | TSTM WND DMG | Birdsboro, PA | Trees down on wires. Time estimated from radar. |
| May 20, 4:40 PM EDT | TSTM WND GST 53 | 1 Ne Reading, PA | Mesonet station EW3190 Reading. |
| May 20, 4:47 PM EDT | TSTM WND DMG | 1 Nne Pottstown, PA | Several trees and large tree limbs down on Charlotte Street and Diamond Street. Time estimated from KDIX radar. |
| May 20, 4:47 PM EDT | TSTM WND DMG | 1 Nne Pottstown, PA | Several trees and large tree limbs down on Charlotte Street and Diamond Street. Time estimated from KDIX radar. |
| May 20, 4:47 PM EDT | TSTM WND DMG | 2 Se Douglass Twp, PA | Wires down along Sunset Drive. Time estimated from radar. |
| May 20, 4:47 PM EDT | TSTM WND DMG | 2 Se Douglass Twp, PA | Wires down along Sunset Drive. Time estimated from radar. |
| May 20, 4:47 PM EDT | TSTM WND DMG | North Coventry Twp, PA | Several large trees down and trees down on power wires on Hanover Street. Trees down on wires on Manatawny St. and Spring St. Time approximate from KDIX radar. |
| May 20, 4:47 PM EDT | TSTM WND DMG | North Coventry Twp, PA | Several large trees down and trees down on power wires on Hanover Street. Trees down on wires on Manatawny St. and Spring St. Time approximate from KDIX radar. |
| May 20, 4:48 PM EDT | TSTM WND DMG | Pottstown, PA | Picture sent in via social media of multiple trees down. Time estimated from radar. |
| May 20, 4:48 PM EDT | TSTM WND DMG | Pottstown, PA | Picture sent in via social media of multiple trees down. Time estimated from radar. |
| May 20, 4:56 PM EDT | TSTM WND GST 51 | 2 Ese Sanatoga, PA | ASOS station KPTW Pottstown. |
| May 20, 4:59 PM EDT | TSTM WND DMG | 3 Ese Lower Pottsgrove, PA | Trees down around Limerick, PA. Time estimated from radar. |
| May 20, 4:59 PM EDT | TSTM WND DMG | 3 Ese Lower Pottsgrove, PA | Trees down around Limerick, PA. Time estimated from radar. |
| May 20, 5:01 PM EDT | TSTM WND DMG | East Coventry Twp, PA | Trees and wires down around East Coventry Township, PA. Time estimated from radar. |
| May 20, 5:01 PM EDT | TSTM WND DMG | East Coventry Twp, PA | Trees and wires down around East Coventry Township, PA. Time estimated from radar. |
| May 20, 5:03 PM EDT | TSTM WND DMG | 1 Ene New Hanover Twp, PA | Widespread trees and wires down in New Hanover Township, PA. Time estimated from radar. |
| May 20, 5:03 PM EDT | TSTM WND DMG | 1 Ene New Hanover Twp, PA | Widespread trees and wires down in New Hanover Township, PA. Time estimated from radar. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| May 20, 2:10 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 8.5 hours before the alert went out and 205 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 47 J/kg
- Mixed-layer CIN
- -204 J/kg
- Mixed-layer LCL
- 1752 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- -79 m²/s²
- 0-3 km storm-relative helicity
- -47 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
237
WUUS51 KPHI 202029
SVRPHI
PAC011-029-091-202115-
/O.NEW.KPHI.SV.W.0034.260520T2029Z-260520T2115Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
429 PM EDT Wed May 20 2026
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
Southeastern Berks County in eastern Pennsylvania...
Northwestern Montgomery County in southeastern Pennsylvania...
Northeastern Chester County in southeastern Pennsylvania...
* Until 515 PM EDT.
* At 428 PM EDT, a severe thunderstorm was located over Birdsboro,
or 7 miles southeast of Reading, moving east at 25 mph. This storm
has a history of producing wind damage.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
* Locations impacted include...
Reading, Pottstown, Phoenixville, Birdsboro, Collegeville,
Royersford, Trappe, Schwenksville, Elverson, Bechtelsville, Green
Lane, New Morgan, Pughtown, Spring Mount, Gilbertsville,
Cedarville, Skippack, Stowe, Boyertown, and Spring City.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
&&
LAT...LON 4019 7595 4036 7592 4039 7563 4037 7540
4014 7539 4014 7575
TIME...MOT...LOC 2028Z 270DEG 20KT 4026 7582
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Fitzsimmons1 follow-up statement
220
WWUS51 KPHI 202052
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
452 PM EDT Wed May 20 2026
PAC011-029-091-202115-
/O.CON.KPHI.SV.W.0034.000000T0000Z-260520T2115Z/
Berks PA-Montgomery PA-Chester PA-
452 PM EDT Wed May 20 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM EDT
FOR SOUTHEASTERN BERKS...NORTHWESTERN MONTGOMERY AND NORTHEASTERN
CHESTER COUNTIES...
At 452 PM EDT, a severe thunderstorm was located over Pottstown, or
16 miles east of Reading, moving east at 25 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
Locations impacted include...
Pottstown, Phoenixville, Birdsboro, Collegeville, Royersford, Trappe,
Schwenksville, Elverson, Bechtelsville, Green Lane, Pughtown, Spring
Mount, Gilbertsville, Cedarville, Skippack, Stowe, Boyertown, Spring
City, Red Hill, and Pottsgrove.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4016 7583 4037 7578 4039 7563 4037 7540
4014 7539 4014 7575
TIME...MOT...LOC 2052Z 270DEG 20KT 4026 7564
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
FitzsimmonsThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 19, 8:04 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Montgomery, Philadelphia | 25 min |
| May 20, 3:57 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Lehigh | 48 min |
| May 20, 4:00 PM EDT | Severe Thunderstorm Warning | PHI | Berks | 45 min |
| May 20, 4:43 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Bucks, Lehigh, Northampton | 47 min |
| May 20, 4:46 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Bucks, Lehigh, Montgomery | 44 min |
| May 20, 4:50 PM EDT | Severe Thunderstorm Warning | PHI | Chester, Delaware | 40 min |
| May 20, 5:10 PM EDT | Severe Thunderstorm Warning | PHI | Chester, Delaware, Montgomery, Philadelphia | 50 min |
| May 20, 5:15 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Chester, Montgomery, Philadelphia | 45 min |
| May 20, 5:24 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Northampton | 51 min |
| May 20, 5:29 PM EDT | Severe Thunderstorm Warning | PHI | Chester, Delaware, Philadelphia | 46 min |
| May 20, 5:40 PM EDT | Flash Flood Warning | PHI | Bucks, Delaware, Montgomery, Philadelphia | 3 hr |
| May 20, 5:41 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Montgomery, Philadelphia | 49 min |
| May 20, 5:52 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Montgomery, Philadelphia | 38 min |
| May 20, 6:01 PM EDT | Severe Thunderstorm Warning | PHI | Delaware, Montgomery, Philadelphia | 44 min |
| May 20, 6:09 PM EDT | Severe Thunderstorm Warning | PHI | Delaware, Philadelphia | 46 min |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 2026Every severe thunderstorm warning in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.