Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 240, NWS Philadelphia/Mount Holly

August 10, 20216 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 10, 2021, 4:01 PM EDT for 6 counties in Pennsylvania. It was in force for 44 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 10, 2021, 4:01 PM EDT (20:01 UTC)
Expired: Aug 10, 2021, 4:45 PM EDT
In force: 44 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Berks County, PA, Carbon County, PA, Chester County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 144 km from the middle of the area, began a volume at 20:04 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 10, 4:12 PM EDT	TSTM WND DMG	2 N Robeson Twp, PA	TREE AND WIRES DOWN ON GOLF COURSE RD. TIME ESTIMATED FROM RADAR.
Aug 10, 4:15 PM EDT	TSTM WND DMG	2 Ssw Macungie, PA	TREE LIMBS DOWN ON WIRES NEAR SHEEPROCK RD. LIKELY ASSOCIATED WITH OUTFLOW WINDS. TIME ESTIMATED FROM RADAR.
Aug 10, 4:25 PM EDT	TSTM WND DMG	1 Ssw Earl Twp, PA	TREE DOWN ON WIRES ON LONG LANE RD. LIKELY ASSOCIATED WITH OUTFLOW WINDS.
Aug 10, 4:35 PM EDT	TSTM WND DMG	1 Wnw Emmaus, PA	CORRECTS TIME OF PREVIOUS TSTM WND DMG REPORT FROM 1 WNW EMMAUS. COUNTY DISPATCH REPORTS ABOUT 5 INSTANCES OF DOWNED TREES AND LIMBS OVER THE SOUTHERN PORTION OF LEHIGH COUNTY. 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 12:00Z, 8.0 hours before the alert went out and 229 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: 529 J/kg
Mixed-layer CIN: -120 J/kg
Mixed-layer LCL: 1096 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

153 
WUUS51 KPHI 102001
SVRPHI
PAC011-025-029-077-091-095-102045-
/O.NEW.KPHI.SV.W.0240.210810T2001Z-210810T2045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
401 PM EDT Tue Aug 10 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Berks County in eastern Pennsylvania...
  Lehigh County in eastern Pennsylvania...
  Northwestern Montgomery County in southeastern Pennsylvania...
  Carbon County in northeastern Pennsylvania...
  North central Chester County in southeastern Pennsylvania...
  Southwestern Northampton County in eastern Pennsylvania...

* Until 445 PM EDT.

* At 401 PM EDT, severe thunderstorms were located along a line
  extending from Delano to near Lenhartsville to near Wernersville,
  moving east 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...
  Allentown, Reading, Lehighton, Bethlehem, Pottstown, Emmaus,
  Wyomissing, Northampton, Palmerton, Birdsboro, Kutztown, Jim
  Thorpe, Slatington, Fleetwood, Sinking Spring, Laureldale,
  Nesquehoning, Weatherly, Wernersville and Walnutport.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 304.
 Northeast Extension between mile markers 48 and 83.
 Interstate 78 in Pennsylvania between mile markers 35 and 65.
 Interstate 176 in Pennsylvania between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4059 7592 4064 7598 4074 7576 4083 7590
      4091 7599 4101 7573 4104 7575 4062 7535
      4012 7577 4015 7590 4034 7617
TIME...MOT...LOC 2001Z 264DEG 24KT 4084 7610 4060 7584 4031 7612 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

SFJ

1 follow-up statement

335 
WWUS51 KPHI 102021
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
421 PM EDT Tue Aug 10 2021

PAC011-025-029-077-091-095-102045-
/O.CON.KPHI.SV.W.0240.000000T0000Z-210810T2045Z/
Berks PA-Lehigh PA-Montgomery PA-Carbon PA-Chester PA-Northampton PA-
421 PM EDT Tue Aug 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM EDT
FOR BERKS...LEHIGH...NORTHWESTERN MONTGOMERY...CARBON...NORTH CENTRAL
CHESTER AND SOUTHWESTERN NORTHAMPTON COUNTIES...

At 421 PM EDT, severe thunderstorms were located along a line
extending from near Hometown to Claussville to Wyomissing, moving
east 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...
Allentown, Reading, Lehighton, Bethlehem, Pottstown, Emmaus,
Wyomissing, Northampton, Palmerton, Birdsboro, Kutztown, Jim Thorpe,
Slatington, Fleetwood, Sinking Spring, Laureldale, Nesquehoning,
Weatherly, Wernersville and Walnutport.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 304.
 Northeast Extension between mile markers 48 and 83.
 Interstate 78 in Pennsylvania between mile markers 38 and 65.
 Interstate 176 in Pennsylvania between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4054 7590 4074 7576 4083 7590 4091 7599
      4101 7573 4104 7575 4062 7535 4012 7577
      4015 7590 4031 7613
TIME...MOT...LOC 2021Z 264DEG 24KT 4085 7592 4061 7566 4032 7595 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

SFJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 10:10 PM EDT	Areal Flood Advisory	PHI	Carbon	3 hr
Aug 10, 3:33 AM EDT	Excessive Heat Warning	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more	4 days
Aug 10, 3:33 AM EDT	Heat Advisory	PHI	Berks, Carbon, Lehigh, Monroe, Northampton	4 days
Aug 10, 5:58 AM EDT	Flash Flood Warning	PHI	Bucks	2 hr
Aug 10, 3:06 PM EDT	Special Weather Statement	PHI	Berks	24 min
Aug 10, 3:33 PM EDT	Special Weather Statement	PHI	Berks	27 min
Aug 10, 3:52 PM EDT	Special Weather Statement	PHI	Berks, Carbon, Lehigh	23 min
Aug 10, 4:18 PM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh	3 hr
Aug 10, 4:33 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Carbon, Chester, Lehigh, Monroe and 2 more	42 min
Aug 10, 5:05 PM EDT	Special Weather Statement	PHI	Northampton	25 min
Aug 10, 5:09 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	51 min
Aug 10, 5:11 PM EDT	Special Weather Statement	PHI	Chester, Montgomery, Philadelphia	34 min
Aug 10, 5:40 PM EDT	Special Weather Statement	PHI	Chester	35 min
Aug 10, 5:58 PM EDT	Special Weather Statement	PHI	Philadelphia	32 min
Aug 10, 6:36 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester	39 min
Aug 10, 7:10 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	65 min
Aug 10, 7:54 PM EDT	Severe Thunderstorm Warning Considerable damage threat	PHI	Chester	51 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.