Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 126, NWS Philadelphia/Mount Holly

July 6, 20214 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 6, 2021, 5:34 PM EDT for 4 counties in Pennsylvania. It was in force for 41 min. 6 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: Jul 6, 2021, 5:34 PM EDT (21:34 UTC)
Expired: Jul 6, 2021, 6:15 PM EDT
In force: 41 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, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 102 km from the middle of the area, began a volume at 21:33 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
Jul 6, 5:41 PM EDT	TSTM WND DMG	West Vincent Twp, PA	TREE BROUGHT DOWN TRANSFORMER AND WIRES. TIME ESTIMATED FROM RADAR.
Jul 6, 5:54 PM EDT	HAIL 1	Ardmore, PA	PEA TO QUARTER SIZE HAIL. REPORT VIA SOCIAL MEDIA. TIME ESTIMATED FROM RADAR.
Jul 6, 6:00 PM EDT	HAIL 0.88	Phoenixville, PA	REPORT VIA SOCIAL MEDIA.
Jul 6, 6:00 PM EDT	HAIL 1	1 E Phoenixville, PA	REPORT VIA SOCIAL MEDIA.
Jul 6, 6:06 PM EDT	TSTM WND DMG	1 Nw West Norriton, PA	LARGE TREE DOWN AT THE JEFFERSONVILLE GOLF COURSE. TIME ESTIMATED FROM RADAR.
Jul 6, 6:06 PM EDT	HAIL 1	Wynnewood, PA

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
Jul 6, 1:32 PM EDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.6 hours before the alert went out and 201 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: 982 J/kg
Mixed-layer CIN: -161 J/kg
Mixed-layer LCL: 1216 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 38 m²/s²
0-3 km storm-relative helicity: 39 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

359 
WUUS51 KPHI 062134
SVRPHI
PAC029-045-091-101-062215-
/O.NEW.KPHI.SV.W.0126.210706T2134Z-210706T2215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
534 PM EDT Tue Jul 6 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southern Montgomery County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  Western Philadelphia County in southeastern Pennsylvania...
  Central Delaware County in southeastern Pennsylvania...

* Until 615 PM EDT.

* At 533 PM EDT, a severe thunderstorm was located over Glenmoore, or
  11 miles northwest of West Chester, moving east at 25 mph.

  HAZARD...60 mph wind gusts and penny size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  Philadelphia, West Chester, Norristown, Phoenixville, West
  Norriton, East Norriton, Coatesville, Yeadon, Downingtown,
  Conshohocken, Folcroft, Ambler, Swarthmore, Collegeville,
  Royersford, Narberth, Trappe, East Lansdowne, Morris Park and
  Pughtown.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 303 and 340.
 Northeast Extension between mile markers 21 and 26.
 Interstate 95 in Pennsylvania between mile markers 15 and 17.
 Interstate 76 in Pennsylvania between mile markers 327 and 350.
 Interstate 676 in Pennsylvania between mile markers 0 and 1.
 Interstate 476 in Pennsylvania between mile markers 4 and 19.

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 4018 7581 4019 7579 4021 7516 3989 7516
      3997 7585
TIME...MOT...LOC 2133Z 273DEG 24KT 4010 7572 

HAIL...0.75IN
WIND...60MPH
 
$$

Fitzsimmons

1 follow-up statement

969 
WWUS51 KPHI 062202 RRA
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
602 PM EDT Tue Jul 6 2021

PAC029-045-091-101-062215-
/O.CON.KPHI.SV.W.0126.000000T0000Z-210706T2215Z/
Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
602 PM EDT Tue Jul 6 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM EDT
FOR SOUTHERN MONTGOMERY...NORTHEASTERN CHESTER...WESTERN PHILADELPHIA
AND CENTRAL DELAWARE COUNTIES...

At 602 PM EDT, a severe thunderstorm was located over Valley Forge,
or 11 miles northeast of West Chester, moving east at 30 mph.

HAZARD...60 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Philadelphia, West Chester, Norristown, Phoenixville, West Norriton,
East Norriton, Yeadon, Conshohocken, Ambler, Collegeville,
Royersford, Narberth, Trappe, East Lansdowne, Morris Park, Bryn Mawr,
Trout Lake, Radnor Township, Gradyville and Broomall.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 313 and 340.
 Northeast Extension between mile markers 21 and 26.
 Interstate 95 in Pennsylvania between mile markers 15 and 17.
 Interstate 76 in Pennsylvania between mile markers 327 and 350.
 Interstate 676 in Pennsylvania between mile markers 0 and 1.
 Interstate 476 in Pennsylvania between mile markers 4 and 19.

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 4019 7564 4019 7555 4021 7516 3989 7516
      3996 7568
TIME...MOT...LOC 2202Z 273DEG 24KT 4009 7546 

HAIL...0.75IN
WIND...60MPH
 
$$

Fitzsimmons

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 6, 4:23 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	52 min
Jul 6, 4:29 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe	76 min
Jul 6, 5:08 PM EDT	Special Weather Statement	PHI	Carbon	37 min
Jul 6, 5:11 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	49 min
Jul 6, 5:15 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe, Northampton	60 min
Jul 6, 5:55 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Northampton	65 min
Jul 6, 6:13 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	31 min
Jul 6, 6:41 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	64 min
Jul 6, 7:01 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	59 min
Jul 6, 7:50 PM EDT	Special Weather Statement	PHI	Lehigh	25 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.