Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 266, NWS Philadelphia/Mount Holly

August 27, 20205 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 27, 2020, 8:26 PM EDT for 5 counties in Pennsylvania. It was in force for 26 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: Aug 27, 2020, 8:26 PM EDT (00:26 UTC)
Expired: Aug 27, 2020, 8:52 PM EDT
In force: 26 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Berks County, PA, Bucks County, PA, Chester County, PA, Lehigh County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 91 km from the middle of the area, began a volume at 00:26 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
Aug 27, 8:27 PM EDT	TSTM WND DMG	1 E Reading, PA	DOWNED TREES AND WIRES NEAR MINERAL SPRING ROAD IN READING. TIME ESTIMATED FROM RADAR.
Aug 27, 8:30 PM EDT	TSTM WND DMG	4 Wsw Allentown, PA	SEVERAL REPORTS OF DOWNED TREES AND WIRES NEAR AND WEST OF ALLENTOWN. TIME ESTIMATED FROM RADAR.
Aug 27, 8:35 PM EDT	TSTM WND GST 44	Allentown Queen City Mu, PA	XLL AWOS MEASURED 38 KT WIND GUST.
Aug 27, 8:42 PM EDT	TSTM WND DMG	2 Sw Upper Saucon Twp, PA	DOWNED TREES AND WIRES NEAR CHESTNUT HILL ROAD. 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 0.4 hours before the alert went out and 222 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: 1190 J/kg
Mixed-layer CIN: -36 J/kg
Mixed-layer LCL: 1443 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 117 m²/s²
0-3 km storm-relative helicity: 161 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 3.5

Open this sounding in Storm Lab

The text

As transmitted.

386 
WUUS51 KPHI 280026
SVRPHI
PAC011-017-029-077-091-280115-
/O.NEW.KPHI.SV.W.0266.200828T0026Z-200828T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
826 PM EDT Thu Aug 27 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Eastern Berks County in eastern Pennsylvania...
  Southeastern Lehigh County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...

* Until 915 PM EDT.

* At 826 PM EDT, severe thunderstorms were located along a line
  extending from near Beersville to near Wyomissing, moving southeast
  at 50 mph.

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

  SOURCE...Radar indicated. A wind gust of 58 mph was also recently 
           reported at Reading Airport.

  IMPACT...Minor damage to vehicles is possible. Wind damage to 
           roofs, siding, trees, and power lines is possible.

* Locations impacted include...
  Allentown, Reading, Norristown, Pottstown, Phoenixville, Lansdale,
  West Norriton, East Norriton, Emmaus, Wyomissing, Quakertown,
  Perkasie, Doylestown, Conshohocken, Hatboro, Souderton, Bedminster,
  Ambler, Birdsboro and Collegeville.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 323 and 343.
 Northeast Extension between mile markers 21 and 63.
 Interstate 76 in Pennsylvania between mile markers 327 and 335.
 Interstate 78 in Pennsylvania between mile markers 44 and 64.
 Interstate 476 in Pennsylvania between mile markers 14 and 19.
 Interstate 176 in Pennsylvania between mile markers 6 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.

&&

LAT...LON 4069 7561 4032 7491 4009 7521 4009 7523
      4001 7530 4002 7533 4006 7536 4005 7541
      4030 7611
TIME...MOT...LOC 0026Z 300DEG 44KT 4077 7542 4029 7595 

HAIL...1.00IN
WIND...60MPH
 
$$

JEO

2 follow-up statements

355 
WWUS51 KPHI 280045
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
845 PM EDT Thu Aug 27 2020

PAC011-017-029-077-091-280115-
/O.CON.KPHI.SV.W.0266.000000T0000Z-200828T0115Z/
Berks PA-Lehigh PA-Montgomery PA-Bucks PA-Chester PA-
845 PM EDT Thu Aug 27 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 915 PM EDT
FOR SOUTHEASTERN BERKS...SOUTHEASTERN LEHIGH...MONTGOMERY...
NORTHWESTERN BUCKS AND NORTHEASTERN CHESTER COUNTIES...

At 845 PM EDT, severe thunderstorms were located along a line
extending from Alpha to near Pughtown, moving southeast at 50 mph.

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

SOURCE...Radar indicated. This storm has a history of producing wind 
         gusts over 60 mph.

IMPACT...Minor damage to vehicles is possible. Wind damage to roofs, 
         siding, trees, and power lines is possible.

Locations impacted include...
Allentown, Norristown, Pottstown, Phoenixville, Lansdale, West
Norriton, East Norriton, Emmaus, Quakertown, Perkasie, Doylestown,
Conshohocken, Hatboro, Souderton, Bedminster, Ambler, Collegeville,
Royersford, Chalfont and Trappe.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 323 and 343.
 Northeast Extension between mile markers 21 and 52.
 Interstate 76 in Pennsylvania between mile markers 327 and 335.
 Interstate 78 in Pennsylvania between mile markers 59 and 63.
 Interstate 476 in Pennsylvania between mile markers 14 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 4032 7491 4009 7521 4009 7523 4001 7530
      4002 7533 4006 7536 4005 7541 4021 7584
      4060 7545
TIME...MOT...LOC 0045Z 300DEG 44KT 4067 7519 4019 7572 

HAIL...1.00IN
WIND...60MPH
 
$$

JEO

739 
WWUS51 KPHI 280052
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
852 PM EDT Thu Aug 27 2020

PAC011-017-029-077-091-280102-
/O.CAN.KPHI.SV.W.0266.000000T0000Z-200828T0115Z/
Berks PA-Lehigh PA-Montgomery PA-Bucks PA-Chester PA-
852 PM EDT Thu Aug 27 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN BERKS...
SOUTHEASTERN LEHIGH...MONTGOMERY...NORTHWESTERN BUCKS AND
NORTHEASTERN CHESTER COUNTIES IS CANCELLED...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning has been cancelled.  However gusty winds are
still possible with these thunderstorms.

LAT...LON 4032 7491 4009 7521 4009 7523 4001 7530
      4002 7533 4006 7536 4005 7541 4021 7584
      4060 7545
TIME...MOT...LOC 0050Z 300DEG 44KT 4064 7512 4016 7565 

$$

JEO

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 27, 8:13 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Northampton	47 min
Aug 27, 8:29 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	46 min
Aug 28, 3:22 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery	53 min
Aug 28, 3:33 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Chester, Lehigh, Montgomery	101 min
Aug 28, 3:36 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester	54 min
Aug 28, 3:52 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	53 min
Aug 28, 3:56 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	49 min
Aug 28, 4:01 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	44 min
Aug 28, 4:39 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Montgomery, Philadelphia	66 min

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.