Alert archive / Delaware / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 257, NWS Philadelphia/Mount Holly

August 25, 2020Kent County, New Castle County, Delaware; Cecil County, Kent County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 25, 2020, 6:31 PM EDT for Kent County, New Castle County, Delaware; Cecil County, Kent County, Maryland. It was in force for 19 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 25, 2020, 6:31 PM EDT (22:31 UTC)
Expired: Aug 25, 2020, 6:50 PM EDT
In force: 19 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Kent County, DE, New Castle County, DE, Cecil County, MD, Kent County, MD

The radar

The Dover AFB radar (KDOX), 62 km from the middle of the area, began a volume at 22:32 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.

Issued	Product	Office	Lasted
Aug 25, 3:34 PM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.5 hours before the alert went out and 151 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 573 J/kg
Mixed-layer CIN: -96 J/kg
Mixed-layer LCL: 1117 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 176 m²/s²
0-3 km storm-relative helicity: 176 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

As transmitted.

490 
WUUS51 KPHI 252231
SVRPHI
DEC001-003-MDC015-029-252315-
/O.NEW.KPHI.SV.W.0257.200825T2231Z-200825T2315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
631 PM EDT Tue Aug 25 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 Kent County in northeastern Maryland...
  Southeastern Cecil County in northeastern Maryland...

* Until 715 PM EDT.

* At 631 PM EDT, a severe thunderstorm was located over Sassafras, or
  near Middletown, moving southeast at 45 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...
  Dover, Middletown, Smyrna, Clayton, Cheswold, Cecilton, Warwick,
  Sassafras, Green Spring, Bohemias Mills, Delaney Corner, Dover
  Speedway, Dover Base Housing, Townsend, Galena, Kenton, Little
  Creek, Leipsic, Chambersville and Kent Acres.

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 3937 7592 3941 7591 3951 7582 3927 7536
      3909 7543
TIME...MOT...LOC 2231Z 305DEG 38KT 3940 7581 

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

JEO

1 follow-up statement

729 
WWUS51 KPHI 252250
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
650 PM EDT Tue Aug 25 2020

DEC001-003-MDC015-029-252300-
/O.CAN.KPHI.SV.W.0257.000000T0000Z-200825T2315Z/
New Castle DE-Kent DE-Kent MD-Cecil MD-
650 PM EDT Tue Aug 25 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN NEW CASTLE...
NORTHERN KENT...NORTHEASTERN KENT AND SOUTHEASTERN CECIL 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.  However gusty winds are
still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 1100 PM EDT for
central and northern Delaware...and northeastern Maryland.

LAT...LON 3937 7592 3941 7591 3951 7582 3927 7536
      3909 7543
TIME...MOT...LOC 2247Z 305DEG 38KT 3928 7560 

$$

JEO

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 25, 5:35 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	40 min
Aug 25, 5:50 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	40 min
Aug 25, 7:15 PM EDT	Special Weather Statement	PHI	Kent	45 min
Aug 25, 7:52 PM EDT	Special Weather Statement	PHI	Talbot	38 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2020 Severe Thunderstorm Warnings in Maryland, 2020 Every 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.