Alert archive / Maryland / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 158, NWS Philadelphia/Mount Holly

July 22, 2020Cecil County, Maryland; Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 22, 2020, 4:38 PM EDT for Cecil County, Maryland; Chester County, Pennsylvania. It was in force for 52 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
Jul 22, 2020, 4:38 PM EDT (20:38 UTC)
Expired
Jul 22, 2020, 5:30 PM EDT
In force
52 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), 112 km from the middle of the area, began a volume at 20:38 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
Jul 22, 2:57 PM EDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 8.6 hours before the alert went out and 149 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 2020-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 248 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2020-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 20 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
248 J/kg
Mixed-layer CIN
-214 J/kg
Mixed-layer LCL
1163 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
20 m²/s²
0-3 km storm-relative helicity
44 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

438 
WUUS51 KPHI 222038
SVRPHI
MDC015-PAC029-222130-
/O.NEW.KPHI.SV.W.0158.200722T2038Z-200722T2130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
438 PM EDT Wed Jul 22 2020

The National Weather Service in Mount Holly NJ has issued a

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

* Until 530 PM EDT.

* At 437 PM EDT, severe thunderstorms were located along a line
  extending from near Adamstown to Rock Springs to Carney, moving
  east at 30 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Calvert, Coatesville, Downingtown, Kennett Square, Oxford,
  Parkesburg, North East, West Grove, Rising Sun, Honey Brook,
  Elverson, Charlestown, Homeville, Glen Roy, Zion, Blake, Barksdale,
  Cochranville, West Nottingham and Octoraro.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 300 and 312.
 Interstate 95 in Maryland between mile markers 91 and 106.

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.

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 3972 7621 3973 7610 3987 7599 3995 7600
      4004 7593 4011 7594 4016 7584 4017 7563
      3978 7573 3939 7602 3939 7604 3943 7600
      3946 7601 3952 7598 3955 7603 3955 7608
      3970 7622
TIME...MOT...LOC 2037Z 260DEG 26KT 4021 7607 3973 7614 3942 7652 

HAIL...0.75IN
WIND...60MPH
 
$$

MPS
2 follow-up statements
228 
WWUS51 KPHI 222100
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
500 PM EDT Wed Jul 22 2020

MDC015-PAC029-222130-
/O.CON.KPHI.SV.W.0158.000000T0000Z-200722T2130Z/
Cecil MD-Chester PA-
500 PM EDT Wed Jul 22 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM EDT
FOR CECIL AND CENTRAL CHESTER COUNTIES...

At 459 PM EDT, severe thunderstorms were located along a line
extending from Elverson to Oxford to near Pleasant Hills, moving east
at 30 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Calvert, Coatesville, Downingtown, Kennett Square, Oxford,
Parkesburg, North East, West Grove, Rising Sun, Honey Brook,
Elverson, Charlestown, Homeville, Zion, Blake, Barksdale,
Cochranville, West Nottingham, Octoraro and Pughtown.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 300 and 312.
 Interstate 95 in Maryland between mile markers 91 and 106.

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.

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 3939 7602 3939 7604 3943 7600 3946 7601
      3952 7598 3955 7603 3955 7608 3965 7617
      3975 7605 3984 7601 3987 7599 3989 7599
      4003 7594 4004 7593 4005 7593 4013 7590
      4016 7584 4017 7563 3978 7573
TIME...MOT...LOC 2059Z 262DEG 27KT 4017 7582 3976 7599 3946 7634 

HAIL...0.75IN
WIND...60MPH
 
$$

MPS
619 
WWUS51 KPHI 222120
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
520 PM EDT Wed Jul 22 2020

MDC015-PAC029-222130-
/O.EXP.KPHI.SV.W.0158.000000T0000Z-200722T2130Z/
Cecil MD-Chester PA-
520 PM EDT Wed Jul 22 2020

...THE SEVERE THUNDERSTORM WARNING FOR CECIL AND CENTRAL CHESTER
COUNTIES WILL EXPIRE AT 530 PM EDT...
    
The storms which prompted the warning have moved out of the area.
Therefore, the warning will be allowed to expire.  However gusty
winds and heavy rain are still possible with these thunderstorms.

A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
northern Delaware...northeastern Maryland...and eastern and
southeastern Pennsylvania.

LAT...LON 3939 7602 3939 7604 3943 7600 3946 7601
      3952 7598 3955 7603 3955 7608 3965 7617
      3975 7605 3984 7601 3987 7599 3989 7599
      4003 7594 4004 7593 4005 7593 4013 7590
      4016 7584 4017 7563 3978 7573
TIME...MOT...LOC 2120Z 260DEG 26KT 4019 7564 3978 7581 3949 7616 

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 9:16 PM EDTSpecial Weather StatementPHIKent29 min
Jul 21, 9:25 PM EDTSpecial Weather StatementPHITalbot35 min
Jul 21, 9:39 PM EDTSevere Thunderstorm WarningPHICaroline, Talbot51 min
Jul 21, 9:46 PM EDTSpecial Weather StatementPHIKent, Queen Anne's29 min
Jul 21, 10:14 PM EDTSpecial Weather StatementPHICaroline46 min
Jul 21, 10:21 PM EDTSevere Thunderstorm WarningPHICaroline, Kent, Queen Anne's54 min
Jul 22, 4:01 PM EDTSevere Thunderstorm WarningPHICecil22 min
Jul 22, 4:47 PM EDTSevere Thunderstorm WarningPHICaroline, Queen Anne's, Talbot43 min
Jul 22, 5:13 PM EDTSevere Thunderstorm WarningPHICecil, Kent, Queen Anne's47 min
Jul 22, 5:23 PM EDTSevere Thunderstorm WarningPHICaroline, Queen Anne's, Talbot52 min
Jul 22, 5:54 PM EDTSevere Thunderstorm WarningPHICaroline, Cecil, Kent, Queen Anne's51 min
Jul 21, 8:45 PM EDTSpecial Weather StatementPHIBerks30 min
Jul 21, 9:20 PM EDTSpecial Weather StatementPHIMontgomery25 min
Jul 22, 1:36 PM EDTSpecial Weather StatementPHICarbon24 min
Jul 22, 1:58 PM EDTSpecial Weather StatementPHIMonroe32 min
Jul 22, 2:10 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton50 min
Jul 22, 3:29 PM EDTSpecial Weather StatementPHILebanon46 min
Jul 22, 3:39 PM EDTSevere Thunderstorm WarningPHIBerks51 min
Jul 22, 4:10 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Northampton65 min
Jul 22, 4:25 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery50 min
Jul 22, 4:49 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Carbon, Lehigh, Monroe, Northampton56 min
Jul 22, 5:09 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Chester, Delaware, Lehigh, Montgomery and 1 more66 min
Jul 22, 5:16 PM EDTSevere Thunderstorm WarningPHIBucks, Monroe, Northampton59 min
Jul 22, 5:23 PM EDTAreal Flood AdvisoryPHINorthampton3 hr
Jul 22, 5:33 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia57 min
Jul 22, 5:40 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery, Philadelphia65 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2020Severe Thunderstorm Warnings in Pennsylvania, 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.