Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 313, NWS Philadelphia/Mount Holly

September 7, 2023New Castle County, Delaware; Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 7, 2023, 6:18 PM EDT for New Castle County, Delaware; Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 42 min. 2 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
Sep 7, 2023, 6:18 PM EDT (22:18 UTC)
Expired
Sep 7, 2023, 7:00 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 New Castle County, DE, Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 104 km from the middle of the area, began a volume at 22:20 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

TimeReportWhereRemark
Sep 7, 6:28 PM EDTHAIL 0.7Downington, PAMixture of pea up to dime sized hail reported in Downingtown.
Sep 7, 6:44 PM EDTHAIL 0.52 Sse Upper Uwchlan Twp, PAReport from mPING: Half-inch (0.50 in.).

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.

IssuedProductOfficeLasted
Sep 7, 1:14 PM EDTSevere Thunderstorm WatchSPC8 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.3 hours before the alert went out and 187 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2023-09-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2091 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2023-09-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 5 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
2091 J/kg
Mixed-layer CIN
-73 J/kg
Mixed-layer LCL
1114 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
27 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

706 
WUUS51 KPHI 072218
SVRPHI
DEC003-PAC029-045-091-072300-
/O.NEW.KPHI.SV.W.0313.230907T2218Z-230907T2300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
618 PM EDT Thu Sep 7 2023

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northern New Castle County in northern Delaware...
  West central Montgomery County in southeastern Pennsylvania...
  Eastern Chester County in southeastern Pennsylvania...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 700 PM EDT.

* At 618 PM EDT, severe thunderstorms were located along a line
  extending from near Downingtown to North Star, moving northeast at
  25 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...
  Wilmington, Newark, West Chester, Phoenixville, West Norriton,
  Westtown, Downingtown, Elsmere, Kennett Square, Collegeville,
  Royersford, Trappe, Schwenksville, Newport, Arden, Stanton,
  Cheyney, Talleyville, Pughtown and Elam.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 306 and 325.
 Interstate 95 in Pennsylvania near mile marker 0.
 Interstate 95 in Delaware between mile markers 12 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4012 7576 4031 7540 3978 7544 3976 7546
      3964 7579 3973 7579
TIME...MOT...LOC 2218Z 229DEG 22KT 4005 7571 3976 7573 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MPS
2 follow-up statements
158 
WWUS51 KPHI 072234
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
634 PM EDT Thu Sep 7 2023

DEC003-072244-
/O.CAN.KPHI.SV.W.0313.000000T0000Z-230907T2300Z/
New Castle DE-
634 PM EDT Thu Sep 7 2023

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN NEW CASTLE COUNTY IS
CANCELLED...

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

A Severe Thunderstorm Watch remains in effect until 900 PM EDT for
southeastern Pennsylvania.

LAT...LON 3985 7561 3978 7574 4017 7567 4031 7540
      4003 7542 3998 7543
TIME...MOT...LOC 2234Z 220DEG 25KT 4017 7563 3988 7568 

$$

PAC029-045-091-072300-
/O.CON.KPHI.SV.W.0313.000000T0000Z-230907T2300Z/
Montgomery PA-Chester PA-Delaware PA-
634 PM EDT Thu Sep 7 2023

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 700 PM EDT
FOR WEST CENTRAL MONTGOMERY...EASTERN CHESTER AND WEST CENTRAL
DELAWARE COUNTIES...

At 634 PM EDT, severe thunderstorms were located along a line
extending from Pughtown to near Kennett Square, moving northeast 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...
West Chester, Phoenixville, West Norriton, Westtown, Downingtown,
Kennett Square, Collegeville, Royersford, Trappe, Schwenksville,
Cheyney, Pughtown, Marshallton, Spring Mount, Lionville-Marchwood,
Valley Forge, Paoli, Chester Springs, Lionville and Hockessin.

This includes Pennsylvania Turnpike between mile markers 311 and 325.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3985 7561 3978 7574 4017 7567 4031 7540
      4003 7542 3998 7543
TIME...MOT...LOC 2234Z 220DEG 25KT 4017 7563 3988 7568 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MPS
673 
WWUS51 KPHI 072250
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
650 PM EDT Thu Sep 7 2023

PAC029-045-091-072300-
/O.EXP.KPHI.SV.W.0313.000000T0000Z-230907T2300Z/
Montgomery PA-Chester PA-Delaware PA-
650 PM EDT Thu Sep 7 2023

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL MONTGOMERY...
EASTERN CHESTER AND WEST CENTRAL DELAWARE COUNTIES WILL EXPIRE AT 700
PM EDT...
            
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 will be allowed to expire.

A Severe Thunderstorm Watch remains in effect until 900 PM EDT for
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 3985 7561 3978 7574 4017 7567 4031 7540
      4003 7542 3998 7543
TIME...MOT...LOC 2250Z 229DEG 22KT 4023 7554 3994 7559 

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 7, 1:10 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh33 min
Sep 7, 1:38 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh19 min
Sep 7, 2:10 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton50 min
Sep 7, 2:13 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh47 min
Sep 7, 2:52 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton24 min
Sep 7, 4:35 PM EDTSpecial Weather StatementPHIBerks25 min
Sep 7, 4:47 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh43 min
Sep 7, 5:17 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Monroe43 min
Sep 7, 5:30 PM EDTSevere Thunderstorm WarningPHIBerks, Chester31 min
Sep 7, 5:34 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton41 min
Sep 7, 5:44 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Lehigh, Montgomery, Northampton46 min
Sep 7, 5:48 PM EDTSevere Thunderstorm WarningPHIChester42 min
Sep 7, 5:57 PM EDTSevere Thunderstorm WarningPHILehigh, Monroe, Northampton34 min
Sep 7, 6:06 PM EDTSpecial Weather StatementPHIBucks, Montgomery24 min
Sep 7, 6:24 PM EDTSevere Thunderstorm WarningPHIBucks, Lehigh, Monroe, Northampton24 min
Sep 7, 7:00 PM EDTSpecial Weather StatementPHIMontgomery30 min
Sep 7, 7:36 PM EDTSevere Thunderstorm WarningPHIBerks, Chester39 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2023Severe Thunderstorm Warnings in Delaware, 2023Every severe thunderstorm warning in 2023

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.