Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 155, NWS Philadelphia/Mount Holly

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

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 22, 2020, 4:01 PM EDT for Chester County, Pennsylvania; Cecil County, Maryland. It was in force for 22 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, 4:01 PM EDT (20:01 UTC)
Expired
Jul 22, 2020, 4:23 PM EDT
In force
22 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 116 km from the middle of the area, began a volume at 20:01 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, 8.0 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 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.

644 
WUUS51 KPHI 222001
SVRPHI
MDC015-PAC029-222045-
/O.NEW.KPHI.SV.W.0155.200722T2001Z-200722T2045Z/

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

The National Weather Service in Mount Holly NJ has issued a

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

* Until 445 PM EDT.

* At 401 PM EDT, a severe thunderstorm was located over Delta, or 17
  miles northwest of Aberdeen, moving east 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...
  Calvert, Oxford, North East, Rising Sun, Charlestown, Homeville,
  Glen Roy, Zion, Lombard, Richardsmere, Woodlawn, West Nottingham,
  Octoraro, Mount Vernon, Conowingo, Rock Springs, Bay View,
  Farmington and Perryville.

This includes Interstate 95 in Maryland between mile markers 91 and
100.
 
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.

In addition to large hail and damaging winds, frequent cloud to
ground lightning is occurring with this storm. Move indoors
immediately. Remember, if you can hear thunder, you are close enough
to be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3985 7602 3987 7599 3990 7600
      3991 7595 3954 7594 3957 7610 3965 7616
      3972 7623
TIME...MOT...LOC 2001Z 267DEG 25KT 3973 7635 

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

MPS
1 follow-up statement
099 
WWUS51 KPHI 222023
SVSPHI

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

MDC015-PAC029-222033-
/O.CAN.KPHI.SV.W.0155.000000T0000Z-200722T2045Z/
Cecil MD-Chester PA-
423 PM EDT Wed Jul 22 2020

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN CECIL AND
SOUTHWESTERN CHESTER COUNTIES IS CANCELLED...
                
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 has been cancelled.

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

LAT...LON 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3985 7602 3987 7599 3990 7600
      3991 7595 3954 7594 3957 7610 3965 7616
      3972 7623
TIME...MOT...LOC 2021Z 267DEG 25KT 3974 7615 

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
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, 4:38 PM EDTSevere Thunderstorm WarningPHIChester52 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
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, 4:47 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

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.