Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 187, NWS Philadelphia/Mount Holly

July 30, 2020Bucks County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 30, 2020, 11:27 PM EDT for Bucks County, Montgomery County, Pennsylvania. It was in force for 33 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, 11:27 PM EDT (03:27 UTC)
Expired: Jul 31, 2020, 12:00 AM EDT
In force: 33 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Bucks County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 65 km from the middle of the area, began a volume at 03:27 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, 11:27 PM EDT	TSTM WND DMG	2 Se North Wales, PA	DOWNED TREE NEAR THE INTERSECTION OF SCHOOL HOUSE LANE AND DEKALB PIKE. TIME ESTIMATED FROM RADAR.
Jul 30, 11:27 PM EDT	TSTM WND DMG	2 W Lower Gwynedd Twp, PA	DOWNED TREE ON SCHOOL HOUSE LANE NEAR PENRITH PLACE. TIME ESTIMATED FROM RADAR.
Jul 30, 11:27 PM EDT	TSTM WND DMG	2 Wnw Lower Gwynedd Twp, PA	DOWNED POWER POLE AND WIRES NEAR THE INTERSECTION OF LATCHSTRING LANE AND PLYMOUTH ROAD. TIME ESTIMATED FROM RADAR.
Jul 30, 11:28 PM EDT	TSTM WND DMG	1 Ese Lansdale, PA	SEVERAL REPORTS OF POWER LINES DOWN NEAR LANSDALE AND NORTH WALES. 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, 3.5 hours before the alert went out and 195 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.

853 
WUUS51 KPHI 310327
SVRPHI
PAC017-091-310400-
/O.NEW.KPHI.SV.W.0187.200731T0327Z-200731T0400Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
1127 PM EDT Thu Jul 30 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  East central Montgomery County in southeastern Pennsylvania...
  Central Bucks County in southeastern Pennsylvania...

* Until midnight EDT.

* At 1127 PM EDT, a severe thunderstorm was located near Ambler, or
  14 miles north of Philadelphia, moving northeast at 30 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Lansdale, Doylestown, Hatboro, Ambler, Chalfont, Hatfield, New
  Hope, Newtown, Bryn Athyn, Ivyland, Stockton, Willow Grove,
  Richboro, Lumberville, Plymouth Meeting, Horsham, North Wales, New
  Britain, Churchville and Fort Washington.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 335 and 345.
 Northeast Extension between mile markers 23 and 30.

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 4026 7486 4009 7522 4009 7524 4024 7537
      4041 7503 4041 7499 4040 7497 4033 7494
      4031 7490
TIME...MOT...LOC 0327Z 240DEG 24KT 4020 7522 

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

JEO

2 follow-up statements

955 
WWUS51 KPHI 310343
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1143 PM EDT Thu Jul 30 2020

PAC017-091-310400-
/O.CON.KPHI.SV.W.0187.000000T0000Z-200731T0400Z/
Montgomery PA-Bucks PA-
1143 PM EDT Thu Jul 30 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EDT
FOR EAST CENTRAL MONTGOMERY AND CENTRAL BUCKS COUNTIES...

At 1142 PM EDT, a severe thunderstorm was located near Ivyland, or 17
miles north of Philadelphia, moving northeast at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Lansdale, Doylestown, Chalfont, Hatfield, Lumberville, North Wales,
New Britain, Brittany Farms-Highlands, Spring House, Kulpsville and
Montgomeryville.

This includes Northeast Extension between mile markers 29 and 30.
 
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 4028 7496 4018 7523 4024 7537 4041 7503
      4040 7499 4034 7498
TIME...MOT...LOC 0342Z 240DEG 24KT 4025 7510 

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

JEO

250 
WWUS51 KPHI 310353
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1153 PM EDT Thu Jul 30 2020

PAC017-091-310402-
/O.EXP.KPHI.SV.W.0187.000000T0000Z-200731T0400Z/
Montgomery PA-Bucks PA-
1153 PM EDT Thu Jul 30 2020

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL MONTGOMERY AND
CENTRAL BUCKS COUNTIES WILL EXPIRE AT MIDNIGHT EDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

LAT...LON 4028 7496 4018 7523 4024 7537 4041 7503
      4040 7499 4034 7498
TIME...MOT...LOC 0352Z 240DEG 24KT 4028 7504 

$$

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, 11:35 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Philadelphia	40 min
Jul 30, 11:51 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery, Northampton	54 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

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 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.