Alert archive / Delaware / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 177, NWS Philadelphia/Mount Holly

July 23, 2020New Castle County, Delaware; Chester County, Pennsylvania; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 23, 2020, 10:26 PM EDT for New Castle County, Delaware; Chester County, Pennsylvania; Cecil County, Maryland. It was in force for 49 min. 2 reports 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: Jul 23, 2020, 10:26 PM EDT (02:26 UTC)
Expired: Jul 23, 2020, 11:15 PM EDT
In force: 49 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties New Castle County, DE, 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 02:29 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

Time	Report	Where	Remark
Jul 23, 10:32 PM EDT	TSTM WND DMG	1 W Rising Sun, MD	WIND-BLOWN DEBRIS ON STATE HIGHWAY 273 AT HARRISVILLE ROAD WITH LANE RESTRICTIONS IN PLACE. TIME ESTIMATED FROM RADAR.
Jul 23, 11:07 PM EDT	TSTM WND DMG	2 Nne Lincoln Universit, PA	DOWNED TREE ON U.S. HIGHWAY 1 NEAR THE ROUTE 896 INTERCHANGE. 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 00:00Z, 2.4 hours before the alert went out and 148 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: 229 J/kg
Mixed-layer CIN: -13 J/kg
Mixed-layer LCL: 2029 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 26 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

400 
WUUS51 KPHI 240226
SVRPHI
DEC003-MDC015-PAC029-240315-
/O.NEW.KPHI.SV.W.0177.200724T0226Z-200724T0315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
1026 PM EDT Thu Jul 23 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northwestern New Castle County in northern Delaware...
  Northern Cecil County in northeastern Maryland...
  Southwestern Chester County in southeastern Pennsylvania...

* Until 1115 PM EDT.

* At 1025 PM EDT, a severe thunderstorm was located over Rising Sun,
  or 10 miles north of Havre De Grace, moving northeast at 20 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...
  Wilmington, Newark, Calvert, Elsmere, Kennett Square, Oxford, North
  East, West Grove, Rising Sun, Homeville, Glen Roy, Zion, Blake,
  Barksdale, Cochranville, North Star, West Nottingham, Octoraro,
  Mount Vernon and Pike Creek.

This includes Interstate 95 in Maryland between mile markers 91 and
104.
 
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 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3985 7602 3987 7599 3989 7599
      3997 7588 3976 7554 3957 7610 3965 7616
      3972 7624
TIME...MOT...LOC 0225Z 230DEG 19KT 3969 7606 

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

Staarmann

2 follow-up statements

116 
WWUS51 KPHI 240251
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1051 PM EDT Thu Jul 23 2020

DEC003-MDC015-PAC029-240315-
/O.CON.KPHI.SV.W.0177.000000T0000Z-200724T0315Z/
New Castle DE-Cecil MD-Chester PA-
1051 PM EDT Thu Jul 23 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1115 PM EDT
FOR NORTHWESTERN NEW CASTLE...NORTHEASTERN CECIL AND SOUTHWESTERN
CHESTER COUNTIES...

At 1049 PM EDT, a severe thunderstorm was located over Calvert, or 
13 miles northwest of Elkton, moving northeast at 20 mph. Another 
severe thunderstorms was located over Glen Westover.

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

SOURCE...Maryland Department of Transportation.

IMPACT...Minor damage to vehicles is possible. Wind damage to roofs, 
         siding, trees, and power lines is possible.

Locations impacted include...
Wilmington, Newark, Calvert, Elsmere, Kennett Square, Oxford, North
East, West Grove, Rising Sun, Homeville, Glen Roy, Zion, Blake,
Barksdale, Cochranville, North Star, West Nottingham, Mount Vernon,
Pike Creek and Fair Hill.

This includes Interstate 95 in Maryland between mile markers 95 and
104.
 
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 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3985 7602 3987 7599 3989 7599
      3997 7588 3976 7554 3959 7603 3965 7613
TIME...MOT...LOC 0249Z 228DEG 16KT 3973 7601 

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

Staarmann

384 
WWUS51 KPHI 240303
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1103 PM EDT Thu Jul 23 2020

DEC003-MDC015-PAC029-240315-
/O.CON.KPHI.SV.W.0177.000000T0000Z-200724T0315Z/
New Castle DE-Cecil MD-Chester PA-
1103 PM EDT Thu Jul 23 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1115 PM EDT
FOR NORTHWESTERN NEW CASTLE...NORTHEASTERN CECIL AND SOUTHWESTERN
CHESTER COUNTIES...

At 1103 PM EDT, a severe thunderstorm was located over North Star, or
near Newark, moving northeast at 25 mph.

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

SOURCE...Maryland Department of Transportation.

IMPACT...Minor damage to vehicles is possible. Wind damage to roofs, 
         siding, trees, and power lines is possible.

Locations impacted include...
Wilmington, Newark, Calvert, Elsmere, Kennett Square, Oxford, North
East, West Grove, Homeville, Glen Roy, Zion, Blake, Barksdale,
Cochranville, North Star, Mount Vernon, Pike Creek, Fair Hill, Glen
Westover and Ashland.

This includes Interstate 95 in Maryland between mile markers 100 and
104.
 
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 3962 7595 3970 7598 3975 7608 3976 7606
      3985 7602 3987 7599 3989 7599 3997 7588
      3976 7554 3962 7594
TIME...MOT...LOC 0303Z 240DEG 23KT 3975 7573 

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

Staarmann

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 23, 11:00 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	45 min
Jul 23, 11:10 PM EDT	Areal Flood Advisory	PHI	New Castle	2 hr
Jul 23, 11:16 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	44 min
Jul 24, 12:24 AM EDT	Flash Flood Warning	PHI	New Castle	114 min
Jul 24, 12:37 AM EDT	River Flood Warning	PHI	New Castle	102 min
Jul 24, 4:35 PM EDT	Special Weather Statement	PHI	New Castle	25 min
Jul 24, 5:34 PM EDT	Special Weather Statement	PHI	Sussex	26 min
Jul 23, 10:44 PM EDT	Areal Flood Advisory	PHI	Chester	2 hr
Jul 23, 11:38 PM EDT	Special Weather Statement	PHI	Chester	37 min
Jul 23, 11:44 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	46 min
Jul 24, 12:32 AM EDT	Special Weather Statement	PHI	Bucks, Montgomery	28 min
Jul 24, 12:42 AM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	48 min
Jul 24, 1:13 AM EDT	Severe Thunderstorm Warning	PHI	Bucks	62 min
Jul 24, 10:43 AM EDT	Flash Flood Warning	PHI	Philadelphia	76 min
Jul 24, 1:43 PM EDT	Areal Flood Advisory	PHI	Bucks, Philadelphia	3 hr
Jul 24, 2:19 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	2 hr
Jul 24, 2:26 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery, Philadelphia	2 hr
Jul 23, 10:18 PM EDT	Special Weather Statement	PHI	Cecil	27 min

Nearby

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