Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 31, NWS Philadelphia/Mount Holly

May 26, 2021Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 26, 2021, 4:52 PM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 38 min. 3 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 26, 2021, 4:52 PM EDT (20:52 UTC)
Expired: May 26, 2021, 5:30 PM EDT
In force: 38 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 122 km from the middle of the area, began a volume at 20:53 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 26, 5:27 PM EDT	TSTM WND DMG	2 Ssw East Nantmeal Twp, PA	DOWNED TREE ON BUCK DRIVE NEAR RABBIT RUN LANE. TIME ESTIMATED FROM RADAR.
May 26, 5:27 PM EDT	TSTM WND DMG	Paoli, PA	DOWNED WIRES ON WISTAR ROAD NEAR CHETWYND ROAD. TIME ESTIMATED FROM RADAR.
May 26, 5:32 PM EDT	TSTM WND DMG	2 S East Nantmeal Twp, PA	DOWNED TREE ON STYER ROAD NEAR MEADOW CREEK LANE. 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 26, 2:48 PM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 8.9 hours before the alert went out and 178 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 478 J/kg
Mixed-layer CIN: -132 J/kg
Mixed-layer LCL: 922 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 50 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

131 
WUUS51 KPHI 262052
SVRPHI
PAC029-045-091-262130-
/O.NEW.KPHI.SV.W.0031.210526T2052Z-210526T2130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
452 PM EDT Wed May 26 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  South central Montgomery County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...
  Central Delaware County in southeastern Pennsylvania...

* Until 530 PM EDT.

* At 452 PM EDT, severe thunderstorms were located along a line
  extending from near New Morgan to near Strasburg, 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...
  West Chester, Coatesville, Westtown, Downingtown, Conshohocken,
  Parkesburg, Honey Brook, Cochranville, Cheyney, Elam, Marshallton,
  Lima, Trout Lake, Chelsea, Radnor Township, Lionville-Marchwood,
  Gradyville, Valley Forge, Broomall and Glenmoore.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 304 and 331.
 Interstate 76 in Pennsylvania between mile markers 327 and 332.
 Interstate 476 in Pennsylvania between mile markers 10 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4004 7593 4011 7594 4014 7588 4010 7528
      3983 7543 3988 7599 3992 7600 3994 7598
      3995 7600
TIME...MOT...LOC 2052Z 269DEG 21KT 4022 7596 4000 7623 

HAIL...<.75IN
WIND...60MPH
 
$$

Meola

1 follow-up statement

748 
WWUS51 KPHI 262117
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
517 PM EDT Wed May 26 2021

PAC029-045-091-262130-
/O.CON.KPHI.SV.W.0031.000000T0000Z-210526T2130Z/
Montgomery PA-Chester PA-Delaware PA-
517 PM EDT Wed May 26 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM EDT
FOR SOUTH CENTRAL MONTGOMERY...CHESTER AND CENTRAL DELAWARE
COUNTIES...

At 517 PM EDT, severe thunderstorms were located along a line
extending from Pughtown to Gap, 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...
West Chester, Coatesville, Westtown, Downingtown, Conshohocken,
Parkesburg, Honey Brook, Cochranville, Cheyney, Elam, Marshallton,
Lima, Trout Lake, Chelsea, Radnor Township, Lionville-Marchwood,
Gradyville, Valley Forge, Broomall and Glenmoore.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 304 and 331.
 Interstate 76 in Pennsylvania between mile markers 327 and 332.
 Interstate 476 in Pennsylvania between mile markers 10 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4004 7593 4011 7594 4014 7588 4010 7528
      3983 7543 3988 7599 3992 7600 3994 7598
      3995 7600
TIME...MOT...LOC 2117Z 272DEG 23KT 4018 7568 4000 7604 

HAIL...<.75IN
WIND...60MPH
 
$$

Deal

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 26, 3:39 PM EDT	Severe Thunderstorm Warning	PHI	Berks	56 min
May 26, 4:10 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	65 min
May 26, 4:46 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery, Northampton	44 min
May 26, 5:27 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Delaware, Montgomery, Philadelphia	48 min
May 26, 5:34 PM EDT	Severe Thunderstorm Warning	PHI	Northampton	41 min
May 26, 5:37 PM EDT	Severe Thunderstorm Warning	PHI	Chester	53 min
May 26, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	67 min
May 26, 6:52 PM EDT	Severe Thunderstorm Warning	PHI	Berks	38 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2021 Every severe thunderstorm warning in 2021

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.