Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 276, NWS Philadelphia/Mount Holly

August 28, 2020Cecil County, Maryland; New Castle County, Delaware; Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 28, 2020, 4:01 PM EDT for Cecil County, Maryland; New Castle County, Delaware; Chester County, Delaware County, Pennsylvania. It was in force for 44 min. 16 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: Aug 28, 2020, 4:01 PM EDT (20:01 UTC)
Expired: Aug 28, 2020, 4:45 PM EDT
In force: 44 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, Delaware County, PA

The radar

The Dover AFB radar (KDOX), 113 km from the middle of the area, began a volume at 20:02 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
Aug 28, 4:10 PM EDT	HAIL 0.88	Chadds Ford Twp, PA
Aug 28, 4:11 PM EDT	TSTM WND DMG	1 Se West Brandywine Tw, PA	DOWNED TREE BLOCKING MANOR ROAD NEAR RED OAK DRIVE. TIME ESTIMATED FROM RADAR.
Aug 28, 4:13 PM EDT	TSTM WND DMG	1 Sw East Brandywine Tw, PA	DOWNED TREE ON HADFIELD ROAD. TIME ESTIMATED FROM RADAR.
Aug 28, 4:16 PM EDT	TSTM WND DMG	2 Wnw East Whiteland Tw, PA	DOWNED TREE LIMBS AND WIRES NEAR SHAMROCK HILL LANE. TIME ESTIMATED FROM RADAR.
Aug 28, 4:18 PM EDT	TSTM WND DMG	1 Nw Caln Twp, PA	DOWNED TREE BLOCKING WESTBOUND ROUTE 30 BYPASS NEAR BAILEY ROAD. TIME ESTIMATED FROM RADAR.
Aug 28, 4:18 PM EDT	TSTM WND DMG	Parkesburg, PA	DOWNED TREES AND WIRES NEAR SECOND AVENUE IN PARKESBURG. TIME ESTIMATED FROM RADAR.
Aug 28, 4:20 PM EDT	TSTM WND DMG	Rising Sun, MD	SEVERAL DOWNED TREES AND POWER LINES.
Aug 28, 4:20 PM EDT	HAIL 0.7	Rising Sun, MD
Aug 28, 4:21 PM EDT	TSTM WND DMG	2 Ssw East Whiteland Tw, PA	DOWNED TREE BLOCKING KING ROAD NEAR RAVINE ROAD. TIME ESTIMATED FROM RADAR.
Aug 28, 4:21 PM EDT	TSTM WND DMG	2 Sw East Whiteland Twp, PA	DOWNED TREE ON LANCASTER AVENUE NEAR LOCKWOOD LANE. TIME ESTIMATED FROM RADAR.
Aug 28, 4:23 PM EDT	TSTM WND DMG	2 N East Goshen Twp., PA	DOWNED TREE ON FOREST LANE NEAR CHESTER ROAD. TIME ESTIMATED FROM RADAR.
Aug 28, 4:26 PM EDT	TSTM WND DMG	1 Nw East Goshen Twp., PA	DOWNED TREE ON CORNWALLIS DRIVE. TIME ESTIMATED FROM RADAR.
Aug 28, 4:26 PM EDT	TSTM WND DMG	1 Sw West Chester, PA	DOWNED TREE BLOCKING WOLLERTON ALLEY NEAR DARLINGTON STREET. TIME ESTIMATED FROM RADAR.
Aug 28, 4:29 PM EDT	TSTM WND DMG	1 S Avondale, PA	DOWNED TREES AND WIRES NEAR MCMILLAN DRIVE IN AVONDALE. TIME ESTIMATED FROM RADAR.
Aug 28, 4:39 PM EDT	TSTM WND DMG	2 Ssw Pennsbury Twp, PA	DOWNED POWER LINES NEAR WEDGEWOOD DRIVE IN FAIRVILLE. TIME ESTIMATED FROM RADAR.
Aug 28, 4:40 PM EDT	TSTM WND DMG	2 Ne Elkton, MD	TREES AND WIRES DOWN.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

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 28, 1:37 PM EDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 8.0 hours before the alert went out and 152 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: 511 J/kg
Mixed-layer CIN: -119 J/kg
Mixed-layer LCL: 1109 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 102 m²/s²
0-3 km storm-relative helicity: 50 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

063 
WUUS51 KPHI 282001
SVRPHI
DEC003-MDC015-PAC029-045-282045-
/O.NEW.KPHI.SV.W.0276.200828T2001Z-200828T2045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
401 PM EDT Fri Aug 28 2020

The National Weather Service in Mount Holly NJ has issued a

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

* Until 445 PM EDT.

* At 401 PM EDT, severe thunderstorms were located along a line
  extending from New Holland to Quarryville to near Jarrettsville,
  moving east at 40 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...
  Newark, West Chester, Elkton, Calvert, Coatesville, Westtown,
  Downingtown, Kennett Square, Oxford, Parkesburg, North East, West
  Grove, Rising Sun, Honey Brook, Charlestown, Glen Roy, Blake, West
  Nottingham, Mount Vernon and Marshallton.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 307 and 321.
 Interstate 95 in Delaware between mile markers 0 and 4.
 Interstate 95 in Maryland between mile markers 91 and 109.

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 3973 7610 3976 7606 3983 7604 3987 7599
      3995 7600 4004 7593 4011 7594 4012 7591
      4008 7549 3974 7562 3940 7597 3941 7601
      3946 7601 3952 7598 3955 7603 3955 7608
      3972 7623
TIME...MOT...LOC 2001Z 288DEG 35KT 4010 7609 3990 7617 3966 7640 

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

Staarmann

1 follow-up statement

098 
WWUS51 KPHI 282023
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
423 PM EDT Fri Aug 28 2020

DEC003-MDC015-PAC029-045-282045-
/O.CON.KPHI.SV.W.0276.000000T0000Z-200828T2045Z/
New Castle DE-Cecil MD-Chester PA-Delaware PA-
423 PM EDT Fri Aug 28 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM EDT
FOR NORTHWESTERN NEW CASTLE...CECIL...CHESTER AND SOUTHWESTERN
DELAWARE COUNTIES...

At 423 PM EDT, severe thunderstorms were located along a line
extending from near Coatesville to near Blake to near Havre De Grace,
moving southeast at 40 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...
Newark, West Chester, Elkton, Calvert, Coatesville, Westtown,
Downingtown, Kennett Square, Oxford, Parkesburg, North East, West
Grove, Rising Sun, Honey Brook, Charlestown, Glen Roy, Blake, West
Nottingham, Mount Vernon and Marshallton.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 307 and 321.
 Interstate 95 in Delaware between mile markers 0 and 4.
 Interstate 95 in Maryland between mile markers 91 and 109.

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 3973 7610 3976 7606 3983 7604 3987 7599
      3995 7600 4004 7593 4011 7594 4012 7591
      4008 7549 3974 7562 3940 7597 3941 7601
      3946 7601 3952 7598 3955 7603 3955 7608
      3972 7623
TIME...MOT...LOC 2023Z 294DEG 36KT 3997 7578 3977 7592 3959 7613 

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
Aug 28, 1:53 PM EDT	Severe Thunderstorm Warning	PHI	Cecil, Kent	52 min
Aug 28, 2:40 PM EDT	Severe Thunderstorm Warning	PHI	Cecil, Kent	50 min
Aug 28, 4:39 PM EDT	Severe Thunderstorm Warning	PHI	Cecil, Kent, Queen Anne's	66 min
Aug 28, 6:17 PM EDT	Severe Thunderstorm Warning	PHI	Caroline	43 min
Aug 28, 3:15 PM EDT	Special Weather Statement	PHI	New Castle	30 min
Aug 28, 3:21 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	24 min
Aug 28, 3:41 PM EDT	Special Weather Statement	PHI	New Castle	34 min
Aug 28, 3:52 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	53 min
Aug 28, 5:40 PM EDT	Special Weather Statement	PHI	Kent	35 min
Aug 28, 7:53 PM EDT	Special Weather Statement	PHI	Sussex	37 min
Aug 27, 8:13 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Northampton	47 min
Aug 27, 8:26 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery	26 min
Aug 27, 8:29 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	46 min
Aug 28, 3:22 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery	53 min
Aug 28, 3:33 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Chester, Lehigh, Montgomery	101 min
Aug 28, 3:36 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester	54 min
Aug 28, 3:56 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	49 min

Nearby

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