Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 36, NWS Philadelphia/Mount Holly

April 21, 20206 counties in Pennsylvania; Hunterdon County, Warren County, New Jersey

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Apr 21, 2020, 1:04 PM EDT for 6 counties in Pennsylvania; Hunterdon County, Warren County, New Jersey. It was in force for 26 min. 8 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: Apr 21, 2020, 1:04 PM EDT (17:04 UTC)
Expired: Apr 21, 2020, 1:30 PM EDT
In force: 26 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Hunterdon County, NJ, Warren County, NJ, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA

What was reported inside it

Time	Report	Where	Remark
Apr 21, 1:15 PM EDT	TSTM WND DMG	2 Wsw East Brandywine T, PA	DOWNED TREE NEAR THE INTERSECTION OF REECEVILLE ROAD AND SWINEHART ROAD. TIME ESTIMATED FROM RADAR.
Apr 21, 1:16 PM EDT	HAIL 0.25	2 Sse Quakertown, PA	0.25 INCH MEASURED. MPING REPORT.
Apr 21, 1:18 PM EDT	TSTM WND DMG	2 Wsw East Brandywine T, PA	DOWNED TREE NEAR THE INTERSECTION OF REECEVILLE ROAD AND SWINEHART ROAD. TIME ESTIMATED FROM RADAR.
Apr 21, 1:20 PM EDT	HAIL 0.25	1 Ene Pohatcong Twp, NJ	0.25 INCH HAIL REPORTED. MPING REPORT.
Apr 21, 1:25 PM EDT	HAIL 0.25	1 Ene Bethlehem Twp, NJ	0.25 INCH HAIL MEASURED. MPING REPORT.
Apr 21, 1:26 PM EDT	TSTM WND DMG	Malvern, PA	DOWNED TREES AND WIRES. TIME ESTIMATED FROM RADAR.
Apr 21, 1:28 PM EDT	HAIL 0.25	1 E Hatfield, PA	0.25 INCH HAIL MEASURED. MPING REPORT.
Apr 21, 1:30 PM EDT	HAIL 0.25	1 S Glen Gardner, NJ	0.25 INCH HAIL MEASURED. MPING REPORT.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 5.1 hours before the alert went out and 208 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: 3 J/kg
Mixed-layer CIN: -125 J/kg
Mixed-layer LCL: 846 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 221 m²/s²
0-3 km storm-relative helicity: 296 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

641 
WUUS51 KPHI 211704
SVRPHI
NJC019-041-PAC017-029-045-091-095-101-211730-
/O.NEW.KPHI.SV.W.0036.200421T1704Z-200421T1730Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
104 PM EDT Tue Apr 21 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Hunterdon County in northwestern New Jersey...
  Southwestern Warren County in northwestern New Jersey...
  Montgomery County in southeastern Pennsylvania...
  Bucks County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...
  Northwestern Philadelphia County in southeastern Pennsylvania...
  Central Delaware County in southeastern Pennsylvania...
  South central Northampton County in eastern Pennsylvania...

* Until 130 PM EDT.

* At 103 PM EDT, severe thunderstorms were located along a line
  extending from Pleasant Valley to near Green Lane to near
  Parkesburg, moving east at 40 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Philadelphia, West Chester, Norristown, Pottstown, Phoenixville,
  Lansdale, West Norriton, East Norriton, Coatesville, Westtown,
  Quakertown, Perkasie, Doylestown, Byram, Downingtown, Conshohocken,
  Hatboro, Souderton, Bedminster and Washington.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 0 and 27.
 Interstate 476 in Pennsylvania between mile markers 9 and 19.
 Pennsylvania Turnpike between exits 312 and 343.
 Northeast Extension between exits A20 and A31.
 Interstate 76 in Pennsylvania between mile markers 327 and 336.

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 4006 7593 4034 7551 4081 7504 4078 7486
      4074 7483 4072 7472 4058 7471 4050 7478
      4051 7480 4049 7478 4022 7503 3983 7552
      3984 7559 3982 7566 3994 7599
TIME...MOT...LOC 1703Z 287DEG 35KT 4074 7501 4032 7542 4000 7591 

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

Davis

1 follow-up statement

204 
WWUS51 KPHI 211717
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
117 PM EDT Tue Apr 21 2020

NJC019-041-PAC017-029-045-091-095-101-211730-
/O.CON.KPHI.SV.W.0036.000000T0000Z-200421T1730Z/
Hunterdon NJ-Warren NJ-Montgomery PA-Bucks PA-Chester PA-
Philadelphia PA-Delaware PA-Northampton PA-
117 PM EDT Tue Apr 21 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 130 PM EDT
FOR HUNTERDON...SOUTHWESTERN WARREN...MONTGOMERY...BUCKS...CHESTER...
NORTHWESTERN PHILADELPHIA...CENTRAL DELAWARE AND SOUTH CENTRAL
NORTHAMPTON COUNTIES...

At 116 PM EDT, severe thunderstorms were located along a line
extending from near Glen Gardner to Souderton to near Downingtown, 
moving east at 40 mph. The strongest winds with the storm are in 
Montgomery and Bucks counties.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Philadelphia, West Chester, Norristown, Pottstown, Phoenixville,
Lansdale, West Norriton, East Norriton, Coatesville, Westtown,
Quakertown, Perkasie, Doylestown, Byram, Downingtown, Conshohocken,
Hatboro, Souderton, Bedminster and Washington.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 1 and 27.
 Interstate 476 in Pennsylvania between mile markers 9 and 19.
 Pennsylvania Turnpike between exits 312 and 343.
 Northeast Extension between exits A20 and A31.
 Interstate 76 in Pennsylvania between mile markers 327 and 336.

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.

This severe thunderstorm may contain little or no lightning. Do not
wait until you hear thunder before taking cover.

&&

LAT...LON 4007 7591 4035 7549 4081 7503 4078 7486
      4074 7483 4072 7472 4058 7471 4051 7477
      4052 7478 4050 7478 4051 7480 4049 7478
      4022 7503 3984 7551 3985 7557 3983 7564
      3995 7597
TIME...MOT...LOC 1716Z 275DEG 33KT 4075 7491 4033 7532 4000 7576 

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
Apr 21, 3:34 AM EDT	Freeze Warning	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more	28 hr
Apr 21, 12:48 PM EDT	Special Weather Statement	PHI	Bucks, Chester, Montgomery	42 min
Apr 21, 1:28 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	32 min
Apr 21, 1:38 PM EDT	Special Weather Statement	PHI	Chester, Delaware	52 min
Apr 21, 1:49 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Philadelphia	56 min
Apr 21, 1:59 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	61 min
Apr 21, 11:44 AM EDT	Coastal Flood Statement	PHI	Ocean	5 hr
Apr 21, 12:23 PM EDT	Special Weather Statement	PHI	Monmouth	37 min
Apr 21, 2:04 PM EDT	Severe Thunderstorm Warning	PHI	Cumberland	56 min
Apr 21, 2:17 PM EDT	Special Marine Warning	PHI		58 min
Apr 21, 2:24 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 2 more	66 min
Apr 21, 2:55 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Monmouth, Ocean	35 min
Apr 21, 3:04 PM EDT	Special Marine Warning	PHI		116 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2020 Severe Thunderstorm Warnings in New Jersey, 2020 Every severe thunderstorm warning in 2020

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.