Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 207, NWS Philadelphia/Mount Holly

July 21, 2021Bucks County, Lehigh County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 21, 2021, 2:03 PM EDT for Bucks County, Lehigh County, Northampton County, Pennsylvania. It was in force for 42 min. 3 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 21, 2021, 2:03 PM EDT (18:03 UTC)
Expired: Jul 21, 2021, 2:45 PM EDT
In force: 42 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Bucks County, PA, Lehigh County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 99 km from the middle of the area, began a volume at 18:07 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 21, 2:05 PM EDT	HAIL 0.75	2 Wnw Allentown, PA	SOUTH WHITEHALL TOWNSHIP.
Jul 21, 2:15 PM EDT	TSTM WND DMG	1 Wsw Allentown, PA	WIDESPREAD TREE DAMAGE IN WEST ALLENTOWN.
Jul 21, 2:20 PM EDT	TSTM WND DMG	2 Sse Allentown, PA	WIRES DOWN SOUTH OF ALLENTOWN. TIME ESTIMATED FROM RADAR.

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 21, 11:56 AM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 6.1 hours before the alert went out and 203 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: 130 J/kg
Mixed-layer CIN: -165 J/kg
Mixed-layer LCL: 1495 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 48 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

792 
WUUS51 KPHI 211803
SVRPHI
PAC017-077-095-211845-
/O.NEW.KPHI.SV.W.0207.210721T1803Z-210721T1845Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
203 PM EDT Wed Jul 21 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Eastern Lehigh County in eastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...
  Southwestern Northampton County in eastern Pennsylvania...

* Until 245 PM EDT.

* At 202 PM EDT, a severe thunderstorm was located over Coffeetown,
  or near Allentown, moving southeast at 30 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Allentown, Bethlehem, Emmaus, Northampton, Quakertown, Perkasie,
  Bedminster, Hellertown, Tinicum, Dublin, Ferndale, Riegelsville,
  Pleasant Valley, Revere, Coffeetown, Ancient Oaks, Lehigh
  University, Claussville, Ottsville and Pipersville.

This includes the following highways...
 Northeast Extension between mile markers 44 and 63.
 Interstate 78 in Pennsylvania between mile markers 50 and 72.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4075 7552 4060 7519 4057 7519 4057 7518
      4058 7513 4055 7508 4054 7507 4049 7506
      4047 7507 4031 7523 4060 7569
TIME...MOT...LOC 1802Z 307DEG 25KT 4064 7552 

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

NC

2 follow-up statements

791 
WWUS51 KPHI 211822
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
222 PM EDT Wed Jul 21 2021

PAC017-077-095-211845-
/O.CON.KPHI.SV.W.0207.000000T0000Z-210721T1845Z/
Lehigh PA-Bucks PA-Northampton PA-
222 PM EDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 245 PM EDT
FOR SOUTHEASTERN LEHIGH...NORTHWESTERN BUCKS AND SOUTH CENTRAL
NORTHAMPTON COUNTIES...

At 222 PM EDT, a severe thunderstorm was located over Hellertown, or
near Allentown, moving southeast at 30 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Allentown, Bethlehem, Emmaus, Quakertown, Perkasie, Bedminster,
Hellertown, Tinicum, Dublin, Ferndale, Riegelsville, Pleasant Valley,
Revere, Lehigh University, Ottsville, Pipersville, Springtown,
Erwinna, Fountain Hill and Sellersville.

This includes the following highways...
 Northeast Extension between mile markers 45 and 52.
 Interstate 78 in Pennsylvania between mile markers 59 and 71.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4065 7540 4060 7519 4057 7519 4057 7518
      4058 7513 4055 7508 4054 7507 4049 7506
      4047 7507 4031 7523 4052 7554
TIME...MOT...LOC 1822Z 307DEG 25KT 4055 7537 

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

NC

386 
WWUS51 KPHI 211835
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
235 PM EDT Wed Jul 21 2021

PAC017-077-095-211845-
/O.EXP.KPHI.SV.W.0207.000000T0000Z-210721T1845Z/
Lehigh PA-Bucks PA-Northampton PA-
235 PM EDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN LEHIGH...
NORTHWESTERN BUCKS AND SOUTH CENTRAL NORTHAMPTON COUNTIES WILL EXPIRE
AT 245 PM EDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

A Severe Thunderstorm Watch remains in effect until 800 PM EDT for
northwestern New Jersey...and eastern and southeastern Pennsylvania.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Mount Holly NJ.

LAT...LON 4065 7540 4060 7519 4057 7519 4057 7518
      4058 7513 4055 7508 4054 7507 4049 7506
      4047 7507 4031 7523 4052 7554
TIME...MOT...LOC 1835Z 307DEG 25KT 4029 7533 

$$

NC

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 21, 1:08 PM EDT	Special Weather Statement	PHI	Lehigh	37 min
Jul 21, 1:11 PM EDT	Special Weather Statement	PHI	Northampton	34 min
Jul 21, 1:27 PM EDT	Severe Thunderstorm Warning	PHI	Berks	48 min
Jul 21, 2:14 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Delaware, Montgomery	19 min
Jul 21, 2:41 PM EDT	Special Weather Statement	PHI	Montgomery	49 min
Jul 21, 2:48 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	42 min
Jul 21, 2:52 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	38 min
Jul 21, 3:16 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	44 min
Jul 21, 3:27 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Philadelphia	33 min
Jul 21, 3:48 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	42 min
Jul 21, 5:59 PM EDT	Special Weather Statement	PHI	Berks	31 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.