Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 189, NWS Philadelphia/Mount Holly

July 30, 20206 counties in Pennsylvania; 4 counties in New Jersey

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 30, 2020, 11:51 PM EDT for 6 counties in Pennsylvania; 4 counties in New Jersey. It was in force for 54 min. 4 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 30, 2020, 11:51 PM EDT (03:51 UTC)
Expired: Jul 31, 2020, 12:45 AM EDT
In force: 54 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Hunterdon County, NJ, Mercer County, NJ, Somerset County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 97 km from the middle of the area, began a volume at 03:55 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 30, 11:53 PM EDT	TSTM WND DMG	1 Wnw Colebrookdale Twp, PA	TREE DOWN ON WIRES CAUSING A POWER OUTAGE NEAR THE INTERSECTION OF SANDY HILL RD AND POWER MILL HOLLOW RD. TIME ESTIMATED FROM RADAR.
Jul 31, 12:04 AM EDT	TSTM WND DMG	1 N Ottsville, PA	TREES AND WIRES DOWN NEAR TABOR ROAD IN OTTSVILLE. TIME ESTIMATED FROM RADAR.
Jul 31, 12:09 AM EDT	TSTM WND DMG	1 N Nockamixon Twp, PA	TREES AND WIRES DOWN NEAR KINTNER HILL ROAD IN NOCKAMIXON TOWNSHIP. TIME ESTIMATED FROM RADAR.
Jul 31, 12:13 AM EDT	TSTM WND DMG	2 Wnw Upper Salford Twp, PA	REPORTS OF WIRES DOWN NEAR ZIEGLERSVILLE. TIME ESTIMATED FROM RADAR.

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 00:00Z, 3.9 hours before the alert went out and 214 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: 2515 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 895 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 79 m²/s²
0-3 km storm-relative helicity: 102 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 4.9

Open this sounding in Storm Lab

The text

As transmitted.

109 
WUUS51 KPHI 310351
SVRPHI
NJC019-021-035-041-PAC011-017-029-077-091-095-310445-
/O.NEW.KPHI.SV.W.0189.200731T0351Z-200731T0445Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
1151 PM EDT Thu Jul 30 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...
  Northwestern Mercer County in central New Jersey...
  Southwestern Somerset County in northern New Jersey...
  Southeastern Berks County in eastern Pennsylvania...
  Southeastern Lehigh County in eastern Pennsylvania...
  Northwestern Montgomery County in southeastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...
  North central Chester County in southeastern Pennsylvania...
  South central Northampton County in eastern Pennsylvania...

* Until 1245 AM EDT.

* At 1151 PM EDT, severe thunderstorms were located along a line
  extending from Lebanon to near Birdsboro, moving northeast at 45
  mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Reading, Bethlehem, Pottstown, Emmaus, Wyomissing, Manville,
  Quakertown, Perkasie, Doylestown, Byram, Souderton, Bedminster,
  Hellertown, Birdsboro, Flemington, Fleetwood, Chalfont, Sinking
  Spring, Tinicum and Laureldale.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 298.
 Northeast Extension between mile markers 32 and 53.
 Interstate 78 in Pennsylvania between mile markers 60 and 71.
 Interstate 78 in New Jersey between mile markers 1 and 27.
 Interstate 176 in Pennsylvania between mile markers 1 and 11.

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.

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4058 7540 4079 7488 4046 7451 4043 7456
      4015 7590 4021 7599 4036 7610
TIME...MOT...LOC 0351Z 228DEG 40KT 4063 7486 4030 7585 

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

JEO

2 follow-up statements

489 
WWUS51 KPHI 310412
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1212 AM EDT Fri Jul 31 2020

NJC041-PAC029-095-310422-
/O.CAN.KPHI.SV.W.0189.000000T0000Z-200731T0445Z/
Warren NJ-Chester PA-Northampton PA-
1212 AM EDT Fri Jul 31 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN WARREN...NORTH
CENTRAL CHESTER AND SOUTH CENTRAL NORTHAMPTON COUNTIES IS
CANCELLED...

The storms which prompted the warning have moved out of
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4043 7456 4023 7560 4024 7561 4023 7562
      4024 7565 4023 7572 4036 7584 4054 7534
      4054 7533 4056 7531 4060 7519 4059 7518
      4062 7516 4074 7487 4046 7451
TIME...MOT...LOC 0412Z 228DEG 40KT 4076 7466 4044 7565 

$$

NJC019-021-035-PAC011-017-077-091-310445-
/O.CON.KPHI.SV.W.0189.000000T0000Z-200731T0445Z/
Hunterdon NJ-Mercer NJ-Somerset NJ-Berks PA-Lehigh PA-Montgomery PA-
Bucks PA-
1212 AM EDT Fri Jul 31 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1245 AM EDT
FOR HUNTERDON...NORTHWESTERN MERCER...SOUTHWESTERN SOMERSET...
SOUTHEASTERN BERKS...SOUTHEASTERN LEHIGH...NORTHWESTERN MONTGOMERY
AND NORTHWESTERN BUCKS COUNTIES...

At 1212 AM EDT, severe thunderstorms were located along a line
extending from near Chester to near Bally, moving northeast at 45
mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Pottstown, Manville, Quakertown, Perkasie, Doylestown, Byram,
Souderton, Bedminster, Flemington, Tinicum, High Bridge, East
Greenville, Clinton, New Hope, Dublin, Hopewell, Glen Gardner,
Ferndale, Hampton and Schwenksville.

This includes the following highways...
 Northeast Extension between mile markers 33 and 48.
 Interstate 78 in New Jersey between mile markers 8 and 25.

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.

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4043 7456 4023 7560 4024 7561 4023 7562
      4024 7565 4023 7572 4036 7584 4054 7534
      4054 7533 4056 7531 4060 7519 4059 7518
      4062 7516 4074 7487 4046 7451
TIME...MOT...LOC 0412Z 228DEG 40KT 4076 7466 4044 7565 

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

JEO

950 
WWUS51 KPHI 310438
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1238 AM EDT Fri Jul 31 2020

NJC019-021-035-PAC011-017-077-091-310448-
/O.EXP.KPHI.SV.W.0189.000000T0000Z-200731T0445Z/
Hunterdon NJ-Mercer NJ-Somerset NJ-Berks PA-Lehigh PA-Montgomery PA-
Bucks PA-
1238 AM EDT Fri Jul 31 2020

...THE SEVERE THUNDERSTORM WARNING FOR HUNTERDON...NORTHWESTERN
MERCER...SOUTHWESTERN SOMERSET...SOUTHEASTERN BERKS...SOUTHEASTERN
LEHIGH...NORTHWESTERN MONTGOMERY AND NORTHWESTERN BUCKS COUNTIES WILL
EXPIRE AT 1245 AM EDT...
    
The storms which prompted the warning have moved out of the area.
Therefore, the warning will be allowed to expire.

LAT...LON 4043 7456 4023 7560 4024 7561 4023 7562
      4024 7565 4023 7572 4036 7584 4054 7534
      4054 7533 4056 7531 4060 7519 4059 7518
      4062 7516 4074 7487 4046 7451
TIME...MOT...LOC 0438Z 228DEG 40KT 4094 7439 4062 7538 

$$

JEO

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 30, 10:11 PM EDT	Special Weather Statement	PHI	Chester, Delaware	49 min
Jul 30, 10:35 PM EDT	Special Weather Statement	PHI	Delaware, Montgomery	40 min
Jul 30, 10:55 PM EDT	Special Weather Statement	PHI	Delaware, Philadelphia	50 min
Jul 30, 11:06 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Montgomery, Philadelphia	39 min
Jul 30, 11:27 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	33 min
Jul 30, 11:35 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Philadelphia	40 min
Jul 31, 12:10 AM EDT	Severe Thunderstorm Warning	PHI	Bucks	50 min
Jul 31, 12:21 AM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Lehigh, Montgomery	4 hr
Jul 30, 10:15 PM EDT	Special Marine Warning	PHI		60 min
Jul 30, 10:36 PM EDT	Special Weather Statement	PHI	Atlantic, Camden, Cumberland, Gloucester, Salem	39 min
Jul 30, 11:40 PM EDT	Special Weather Statement	PHI	Hunterdon	50 min
Jul 31, 12:33 AM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer, Middlesex, Monmouth, Morris, Ocean and 1 more	42 min
Jul 31, 12:54 AM EDT	Areal Flood Advisory	PHI	Hunterdon, Mercer, Middlesex, Monmouth, Somerset	4 hr
Jul 31, 1:10 AM EDT	Severe Thunderstorm Warning	PHI	Middlesex, Monmouth, Morris, Somerset	35 min
Jul 31, 1:29 AM EDT	Flash Flood Warning	PHI	Middlesex, Somerset	4 hr

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; radar from the NEXRAD Level II archive.