Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020
Severe Thunderstorm Warning 238, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 12, 2020, 3:20 PM EDT for Cecil County, Maryland; Chester County, Delaware County, Pennsylvania; New Castle County, Delaware. It was in force for 29 min. 3 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 12, 2020, 3:20 PM EDT (19:20 UTC)
- Expired
- Aug 12, 2020, 3:49 PM EDT
- In force
- 29 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Hail
- 0.75 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), 93 km from the middle of the area, began a volume at 19:20 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 12, 3:24 PM EDT | TSTM WND DMG | 1 Nw Toughkenamon, PA | DOWNED TREE IN WIRES NEAR CHURCH ROAD AND THIRD STREET. TIME ESTIMATED FROM RADAR. |
| Aug 12, 3:29 PM EDT | TSTM WND DMG | Avondale, PA | TREE DOWN BLOCKING BALTIMORE PIKE. TIME ESTIMATED FROM RADAR. |
| Aug 12, 3:33 PM EDT | TSTM WND DMG | 1 Nw Toughkenamon, PA | TREE AND WIRES DOWN BLOCKING CHURCH RD AT POLO RD NEAR LOCH NAIRN GOLF LINKS. 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, 7.3 hours before the alert went out and 165 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.
- Mixed-layer CAPE
- 127 J/kg
- Mixed-layer CIN
- -149 J/kg
- Mixed-layer LCL
- 1202 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- 0 m²/s²
- 0-3 km storm-relative helicity
- 48 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
321
WUUS51 KPHI 121920
SVRPHI
DEC003-MDC015-PAC029-045-122000-
/O.NEW.KPHI.SV.W.0238.200812T1920Z-200812T2000Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
320 PM EDT Wed Aug 12 2020
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
Northern New Castle County in northern Delaware...
Northeastern Cecil County in northeastern Maryland...
Southern Chester County in southeastern Pennsylvania...
Southwestern Delaware County in southeastern Pennsylvania...
* Until 400 PM EDT.
* At 320 PM EDT, a severe thunderstorm was located over Kemblesville,
or 8 miles northwest of Newark, 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...
Wilmington, Newark, West Chester, Elkton, Calvert, Pennsville,
Westtown, Elsmere, Kennett Square, New Castle, Penns Grove, Oxford,
North East, West Grove, Rising Sun, Delaware City, Charlestown,
Newport, Arden and Glen Roy.
This includes the following highways...
Interstate 95 in Delaware between mile markers 0 and 20.
Interstate 95 in Maryland between mile markers 91 and 109.
Interstate 295 in New Jersey near mile marker 0.
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.
&&
LAT...LON 3980 7604 3999 7549 3973 7547 3969 7551
3962 7547 3962 7549 3964 7549 3966 7552
3963 7556 3960 7556 3960 7552 3959 7554
3957 7550 3954 7553 3951 7598 3952 7598
3955 7602 3955 7609 3960 7613
TIME...MOT...LOC 1920Z 248DEG 18KT 3978 7583
HAIL...<.75IN
WIND...60MPH
$$
Gorse2 follow-up statements
260
WWUS51 KPHI 121940
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
340 PM EDT Wed Aug 12 2020
DEC003-MDC015-PAC029-045-122000-
/O.CON.KPHI.SV.W.0238.000000T0000Z-200812T2000Z/
New Castle DE-Cecil MD-Chester PA-Delaware PA-
340 PM EDT Wed Aug 12 2020
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR NORTHERN NEW CASTLE...NORTHEASTERN CECIL...SOUTHERN CHESTER AND
SOUTHWESTERN DELAWARE COUNTIES...
At 339 PM EDT, a severe thunderstorm was located over Hockessin, or 7
miles north of Newark, moving east at 20 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
Locations impacted include...
Wilmington, Newark, West Chester, Elkton, Calvert, Pennsville,
Westtown, Elsmere, Kennett Square, New Castle, Penns Grove, Oxford,
North East, West Grove, Rising Sun, Delaware City, Charlestown,
Newport, Arden and Glen Roy.
This includes the following highways...
Interstate 95 in Delaware between mile markers 0 and 20.
Interstate 95 in Maryland between mile markers 91 and 109.
Interstate 295 in New Jersey near mile marker 0.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Protecting yourself from immediate threats to life and safety shall
take priority. Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.
For your protection move to an interior room on the lowest floor of a
building.
Frequent cloud to ground lightning is occurring with this storm. Move
indoors immediately. Lightning is one of nature's leading killers.
Remember, if you can hear thunder, you are close enough to be struck
by lightning.
&&
LAT...LON 3980 7604 3999 7549 3973 7547 3969 7551
3962 7547 3962 7549 3964 7549 3966 7552
3963 7556 3960 7556 3960 7552 3959 7554
3957 7550 3954 7553 3951 7598 3952 7598
3955 7602 3955 7609 3960 7613
TIME...MOT...LOC 1939Z 262DEG 17KT 3978 7571
HAIL...<.75IN
WIND...60MPH
$$
Gorse780
WWUS51 KPHI 121949
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
349 PM EDT Wed Aug 12 2020
DEC003-MDC015-PAC029-045-121958-
/O.CAN.KPHI.SV.W.0238.000000T0000Z-200812T2000Z/
New Castle DE-Cecil MD-Chester PA-Delaware PA-
349 PM EDT Wed Aug 12 2020
...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN NEW CASTLE...
NORTHEASTERN CECIL...SOUTHERN CHESTER AND SOUTHWESTERN DELAWARE
COUNTIES IS CANCELLED...
The storms 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 and
heavy rain are still possible with these thunderstorms.
LAT...LON 3980 7604 3999 7549 3973 7547 3969 7551
3962 7547 3962 7549 3964 7549 3966 7552
3963 7556 3960 7556 3960 7552 3959 7554
3957 7550 3954 7553 3951 7598 3952 7598
3955 7602 3955 7609 3960 7613
TIME...MOT...LOC 1947Z 248DEG 18KT 3980 7565
$$
GorseThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 12, 12:43 PM EDT | Areal Flood Advisory | PHI | Cecil | 3 hr |
| Aug 12, 12:55 PM EDT | Areal Flood Advisory | PHI | Cecil, Kent | 3 hr |
| Aug 12, 3:06 PM EDT | Areal Flood Advisory | PHI | Caroline, Queen Anne's | 3 hr |
| Aug 12, 3:36 PM EDT | Flash Flood Warning | PHI | Cecil | 108 min |
| Aug 12, 3:46 PM EDT | Flash Flood Warning | PHI | Caroline | 3 hr |
| Aug 12, 4:02 PM EDT | Special Weather Statement | PHI | Caroline | 28 min |
| Aug 12, 4:11 PM EDT | Areal Flood Warning | PHI | Caroline, Talbot | 3 hr |
| Aug 12, 4:43 PM EDT | Areal Flood Advisory | PHI | Cecil, Kent | 54 min |
| Aug 12, 11:48 AM EDT | Special Weather Statement | PHI | Philadelphia | 27 min |
| Aug 12, 1:12 PM EDT | Severe Thunderstorm Warning | PHI | Chester, Delaware, Montgomery, Philadelphia | 48 min |
| Aug 12, 1:47 PM EDT | Flash Flood Warning | PHI | Chester, Delaware | 2 hr |
| Aug 12, 1:54 PM EDT | Severe Thunderstorm Warning | PHI | Chester, Delaware, Montgomery, Philadelphia | 51 min |
| Aug 12, 2:04 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Montgomery, Philadelphia | 21 min |
| Aug 12, 2:40 PM EDT | Flash Flood Warning | PHI | Chester, Delaware, Montgomery, Philadelphia | 3 hr |
| Aug 12, 2:44 PM EDT | Severe Thunderstorm Warning | PHI | Delaware, Philadelphia | 46 min |
| Aug 12, 5:04 PM EDT | Areal Flood Advisory | PHI | Lehigh, Northampton | 56 min |
| Aug 12, 5:09 PM EDT | Areal Flood Warning | PHI | Berks | 51 min |
| Aug 12, 12:55 PM EDT | Special Weather Statement | PHI | Kent | 35 min |
| Aug 12, 1:06 PM EDT | Flash Flood Warning | PHI | Kent, New Castle | 3 hr |
| Aug 12, 1:37 PM EDT | Areal Flood Advisory | PHI | New Castle | 3 hr |
| Aug 12, 2:38 PM EDT | Severe Thunderstorm Warning | PHI | Kent | 52 min |
| Aug 12, 3:15 PM EDT | Severe Thunderstorm Warning | PHI | Kent, Sussex | 45 min |
| Aug 12, 3:31 PM EDT | Flash Flood Warning | PHI | Kent | 3 hr |
| Aug 12, 4:00 PM EDT | Special Weather Statement | PHI | Kent | 30 min |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 2020Severe 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.