Alert archive / Delaware / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 204, NWS Philadelphia/Mount Holly

August 4, 2020Kent County, Sussex County, Delaware; Caroline County, Talbot County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 4, 2020, 8:21 PM EDT for Kent County, Sussex County, Delaware; Caroline County, Talbot County, Maryland. It was in force for 39 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
Aug 4, 2020, 8:21 PM EDT (00:21 UTC)
Expired
Aug 4, 2020, 9:00 PM EDT
In force
39 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Kent County, DE, Sussex County, DE, Caroline County, MD, Talbot County, MD

The radar

The Dover AFB radar (KDOX), 35 km from the middle of the area, began a volume at 00:22 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 nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 00:00Z, 0.4 hours before the alert went out and 110 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, Wallops Is Stn, VA at 00:00Z on 2020-08-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 272 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, Wallops Is Stn, VA at 00:00Z on 2020-08-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 84 square meters per square second.19395878Sfc1 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
272 J/kg
Mixed-layer CIN
-48 J/kg
Mixed-layer LCL
1064 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
84 m²/s²
0-3 km storm-relative helicity
75 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.4

Open this sounding in Storm Lab

The text

As transmitted.

994 
WUUS51 KPHI 050021
SVRPHI
DEC001-005-MDC011-041-050100-
/O.NEW.KPHI.SV.W.0204.200805T0021Z-200805T0100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
821 PM EDT Tue Aug 4 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northwestern Sussex County in southern Delaware...
  Southwestern Kent County in central Delaware...
  Northeastern Talbot County in eastern Maryland...
  Caroline County in eastern Maryland...

* Until 900 PM EDT.

* At 821 PM EDT, a severe thunderstorm was located over Griffin, or
  12 miles northeast of Easton, moving east at 20 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Milford, Denton, Harrington, Bridgeville, Greensboro, Ridgely,
  Queen Anne, Tanyard, Harmony, Smithville, Jumptown, Agner,
  Matthews, Griffin, Andrewsville, Cordova, Felton, Greenwood,
  Frederica and Houston.

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 3874 7603 3892 7598 3893 7595 3896 7594
      3902 7545 3871 7548
TIME...MOT...LOC 0021Z 263DEG 19KT 3887 7587 

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

NC
2 follow-up statements
264 
WWUS51 KPHI 050047
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
847 PM EDT Tue Aug 4 2020

MDC011-041-050056-
/O.CAN.KPHI.SV.W.0204.000000T0000Z-200805T0100Z/
Talbot MD-Caroline MD-
847 PM EDT Tue Aug 4 2020

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN TALBOT AND
CAROLINE COUNTIES IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 3873 7571 3893 7573 3899 7573 3902 7545
      3871 7548
TIME...MOT...LOC 0046Z 263DEG 19KT 3889 7570 

$$

DEC001-005-050100-
/O.CON.KPHI.SV.W.0204.000000T0000Z-200805T0100Z/
Sussex DE-Kent DE-
847 PM EDT Tue Aug 4 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM EDT
FOR NORTHWESTERN SUSSEX AND SOUTHWESTERN KENT COUNTIES...

At 846 PM EDT, a severe thunderstorm was located near Andrewsville,
or 20 miles northeast of Hurlock, moving east at 20 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Milford, Harrington, Bridgeville, Andrewsville, Felton, Greenwood,
Frederica, Houston and Farmington.

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 3873 7571 3893 7573 3899 7573 3902 7545
      3871 7548
TIME...MOT...LOC 0046Z 263DEG 19KT 3889 7570 

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

NC
149 
WWUS51 KPHI 050058
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
858 PM EDT Tue Aug 4 2020

DEC001-005-050107-
/O.EXP.KPHI.SV.W.0204.000000T0000Z-200805T0100Z/
Sussex DE-Kent DE-
858 PM EDT Tue Aug 4 2020

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN SUSSEX AND
SOUTHWESTERN KENT COUNTIES WILL EXPIRE AT 900 PM EDT...
                
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 will be allowed to expire.  However gusty
winds are still possible with this thunderstorm.

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 3873 7571 3893 7573 3899 7573 3902 7545
      3871 7548
TIME...MOT...LOC 0057Z 263DEG 19KT 3889 7570 

$$

NC

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 4, 9:00 PM EDTSpecial Weather StatementPHIKent30 min
Aug 4, 10:25 PM EDTSpecial Weather StatementPHINew Castle50 min
Aug 4, 8:03 PM EDTSpecial Weather StatementPHICaroline, Talbot42 min

Nearby

Severe Thunderstorm Warnings in Delaware, 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.