Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 286, NWS Philadelphia/Mount Holly

September 2, 2020Chester County, Pennsylvania; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 2, 2020, 8:07 PM EDT for Chester County, Pennsylvania; Cecil County, Maryland. It was in force for 53 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Sep 2, 2020, 8:07 PM EDT (00:07 UTC)
Expired
Sep 2, 2020, 9:00 PM EDT
In force
53 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 103 km from the middle of the area, began a volume at 00:06 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Sep 2, 6:43 PM EDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 0.1 hours before the alert went out and 144 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 00:00Z on 2020-09-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1723 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 00:00Z on 2020-09-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 182 square meters per square second.193958Sfc1 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
1723 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
847 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
182 m²/s²
0-3 km storm-relative helicity
229 m²/s²
Significant tornado parameter
1.4
Supercell composite
8.6

Open this sounding in Storm Lab

The text

As transmitted.

612 
WUUS51 KPHI 030007
SVRPHI
MDC015-PAC029-030100-
/O.NEW.KPHI.SV.W.0286.200903T0007Z-200903T0100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
807 PM EDT Wed Sep 2 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Cecil County in northeastern Maryland...
  Southwestern Chester County in southeastern Pennsylvania...

* Until 900 PM EDT.

* At 806 PM EDT, a severe thunderstorm was located near
  Jarrettsville, or 16 miles northwest of Aberdeen, moving east at 35
  mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Elkton, Calvert, Oxford, North East, West Grove, Rising Sun,
  Charlestown, Cecilton, Warwick, Homeville, Glen Roy, Zion, Blake,
  Barksdale, Bohemias Mills, West Nottingham, Octoraro, Brantwood,
  Mount Vernon and Fair Hill.

This includes Interstate 95 in Maryland between mile markers 91 and
109.
 
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 3972 7614 3974 7612 3973 7610 3986 7601
      3989 7578 3972 7577 3972 7579 3962 7579
      3938 7577 3943 7600 3946 7601 3952 7598
      3955 7603 3955 7608 3972 7623
TIME...MOT...LOC 0006Z 271DEG 29KT 3967 7642 

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

Iovino
1 follow-up statement
233 
WWUS51 KPHI 030032
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
832 PM EDT Wed Sep 2 2020

MDC015-PAC029-030100-
/O.CON.KPHI.SV.W.0286.000000T0000Z-200903T0100Z/
Cecil MD-Chester PA-
832 PM EDT Wed Sep 2 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM EDT
FOR CECIL AND SOUTHWESTERN CHESTER COUNTIES...

At 831 PM EDT, a severe thunderstorm was located over Octoraro, or 8
miles north of Havre De Grace, moving east at 35 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Elkton, Calvert, Oxford, North East, West Grove, Rising Sun,
Charlestown, Cecilton, Warwick, Homeville, Glen Roy, Zion, Blake,
Barksdale, Bohemias Mills, West Nottingham, Octoraro, Brantwood,
Mount Vernon and Fair Hill.

This includes Interstate 95 in Maryland between mile markers 91 and
109.
 
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 3972 7614 3974 7612 3973 7610 3986 7601
      3989 7578 3972 7577 3972 7579 3962 7579
      3938 7577 3943 7600 3946 7601 3952 7598
      3955 7603 3955 7608 3972 7623
TIME...MOT...LOC 0031Z 271DEG 29KT 3967 7615 

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

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 3, 7:14 PM EDTSpecial Weather StatementPHIBucks46 min
Sep 3, 7:16 PM EDTSpecial Weather StatementPHIMontgomery44 min
Sep 3, 7:17 PM EDTSpecial Weather StatementPHIDelaware, Philadelphia43 min
Sep 2, 8:47 PM EDTSevere Thunderstorm WarningPHICaroline, Cecil, Kent, Queen Anne's, Talbot58 min
Sep 2, 10:08 PM EDTSevere Thunderstorm WarningPHICaroline, Queen Anne's, Talbot67 min
Sep 3, 5:47 PM EDTSevere Thunderstorm WarningPHICaroline, Kent, Queen Anne's, Talbot73 min
Sep 3, 6:48 PM EDTSevere Thunderstorm WarningPHICaroline, Talbot57 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2020Severe Thunderstorm Warnings in Maryland, 2020Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.