Alert archive / Maryland / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 218, NWS Philadelphia/Mount Holly

August 7, 2020Kent County, New Castle County, Delaware; Cecil County, Kent County, Queen Anne's County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 7, 2020, 6:12 PM EDT for Kent County, New Castle County, Delaware; Cecil County, Kent County, Queen Anne's County, Maryland. It was in force for 63 min. 1 report 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 7, 2020, 6:12 PM EDT (22:12 UTC)
Expired
Aug 7, 2020, 7:15 PM EDT
In force
63 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Kent County, DE, New Castle County, DE, Cecil County, MD, Kent County, MD, Queen Anne's County, MD

The radar

The Dover AFB radar (KDOX), 80 km from the middle of the area, began a volume at 22:14 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
Aug 7, 7:21 PM EDTTSTM WND DMGStill Pond, MDDELAYED REPORT. WIND-BLOWN DEBRIS CLOSED STATE HIGHWAY 292 NEAR STATE HIGHWAY 566. 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, 10.2 hours before the alert went out and 139 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 2020-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 301 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 2020-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -37 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
301 J/kg
Mixed-layer CIN
-67 J/kg
Mixed-layer LCL
665 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
-37 m²/s²
0-3 km storm-relative helicity
18 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

292 
WUUS51 KPHI 072212
SVRPHI
DEC001-003-MDC015-029-035-072315-
/O.NEW.KPHI.SV.W.0218.200807T2212Z-200807T2315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
612 PM EDT Fri Aug 7 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southwestern New Castle County in northern Delaware...
  Northern Kent County in central Delaware...
  Northeastern Queen Anne's County in northeastern Maryland...
  Northeastern Kent County in northeastern Maryland...
  Cecil County in northeastern Maryland...

* Until 715 PM EDT.

* At 611 PM EDT, a severe thunderstorm was located over Aberdeen,
  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...
  Dover, Middletown, Elkton, Smyrna, North East, Clayton, Delaware
  City, Cheswold, Charlestown, Cecilton, Millington, Betterton,
  Hartly, Warwick, Woodland Beach, Bohemias Mills, Port Penn,
  Brantwood, Delaney Corner and Crumpton.

This includes Interstate 95 in Maryland between mile markers 91 and
99.
 
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.

In addition to 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 3933 7614 3937 7611 3937 7606 3942 7600
      3946 7601 3952 7598 3955 7603 3955 7609
      3962 7614 3965 7610 3957 7559 3955 7556
      3945 7555 3921 7534 3916 7578
TIME...MOT...LOC 2211Z 290DEG 28KT 3950 7618 

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

BAH
2 follow-up statements
980 
WWUS51 KPHI 072231
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
631 PM EDT Fri Aug 7 2020

DEC001-003-MDC015-029-035-072315-
/O.CON.KPHI.SV.W.0218.000000T0000Z-200807T2315Z/
New Castle DE-Kent DE-Queen Anne's MD-Kent MD-Cecil MD-
631 PM EDT Fri Aug 7 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 PM EDT
FOR SOUTHWESTERN NEW CASTLE...NORTHERN KENT...NORTHEASTERN QUEEN
ANNE'S...NORTHEASTERN KENT AND CECIL COUNTIES...

At 631 PM EDT, a severe thunderstorm was located near Aberdeen
Proving Ground, moving east at 25 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Dover, Middletown, Elkton, Smyrna, North East, Clayton, Delaware
City, Cheswold, Charlestown, Cecilton, Millington, Betterton, Hartly,
Warwick, Woodland Beach, Bohemias Mills, Port Penn, Brantwood,
Delaney Corner and Crumpton.

This includes Interstate 95 in Maryland between mile markers 91 and
99.
 
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.

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

&&

LAT...LON 3933 7614 3937 7611 3937 7606 3942 7600
      3946 7601 3952 7598 3955 7603 3955 7609
      3962 7614 3965 7610 3957 7559 3955 7556
      3945 7555 3921 7534 3916 7578
TIME...MOT...LOC 2231Z 289DEG 21KT 3947 7606 

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

BAH
894 
WWUS51 KPHI 072306
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
706 PM EDT Fri Aug 7 2020

DEC001-003-MDC015-029-035-072316-
/O.EXP.KPHI.SV.W.0218.000000T0000Z-200807T2315Z/
New Castle DE-Kent DE-Queen Anne's MD-Kent MD-Cecil MD-
706 PM EDT Fri Aug 7 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN NEW CASTLE...
NORTHERN KENT...NORTHEASTERN QUEEN ANNE'S...NORTHEASTERN KENT AND
CECIL COUNTIES WILL EXPIRE AT 715 PM EDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.

Remember, a Severe Thunderstorm Warning #218 still remains in effect

LAT...LON 3933 7614 3937 7611 3937 7606 3942 7600
      3946 7601 3952 7598 3955 7603 3955 7609
      3962 7614 3965 7610 3957 7559 3955 7556
      3945 7555 3921 7534 3916 7578
TIME...MOT...LOC 2306Z 290DEG 28KT 3938 7574 

$$

BAH

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 7, 5:03 PM EDTFlash Flood WarningPHINew Castle5 hr
Aug 7, 5:38 PM EDTSevere Thunderstorm WarningPHINew Castle52 min
Aug 7, 5:49 PM EDTTornado WarningPHINew Castle26 min
Aug 7, 5:57 PM EDTSevere Thunderstorm WarningPHINew Castle48 min
Aug 7, 6:00 PM EDTTornado WarningPHINew Castle30 min
Aug 7, 6:43 PM EDTAreal Flood AdvisoryPHIKent, New Castle4 hr
Aug 7, 7:04 PM EDTSevere Thunderstorm WarningPHIKent, New Castle41 min
Aug 7, 7:21 PM EDTFlash Flood WarningPHIKent, New Castle5 hr
Aug 7, 7:28 PM EDTRiver Flood WarningPHINew Castle2 hr
Aug 7, 7:36 PM EDTSpecial Weather StatementPHIKent39 min
Aug 7, 4:41 PM EDTAreal Flood AdvisoryPHICecil3 hr
Aug 7, 7:44 PM EDTFlash Flood WarningPHICaroline, Kent, Queen Anne's4 hr

Nearby

Severe Thunderstorm Warnings in Maryland, 2020Severe Thunderstorm Warnings in Delaware, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.