Alert archive / Delaware / Severe Thunderstorm Warnings in 2020
Severe Thunderstorm Warning 239, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 17, 2020, 5:38 PM EDT for New Castle County, Delaware; Chester County, Pennsylvania. It was in force for 37 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 17, 2020, 5:38 PM EDT (21:38 UTC)
- Expired
- Aug 17, 2020, 6:15 PM EDT
- In force
- 37 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Hail
- 0.88 in
- Wind
- 60.0 mph
Counties New Castle County, DE, Chester County, PA
The radar
The Dover AFB radar (KDOX), 128 km from the middle of the area, began a volume at 21:40 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
Washington/Dulle, VA (KIAD), launched 12:00Z, 9.6 hours before the alert went out and 164 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
- 9 J/kg
- Mixed-layer CIN
- -89 J/kg
- Mixed-layer LCL
- 685 m above ground
- 0-6 km bulk shear
- 34 kt
- 0-1 km storm-relative helicity
- 48 m²/s²
- 0-3 km storm-relative helicity
- 54 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
041
WUUS51 KPHI 172138
SVRPHI
DEC003-PAC029-172215-
/O.NEW.KPHI.SV.W.0239.200817T2138Z-200817T2215Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
538 PM EDT Mon Aug 17 2020
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
Northwestern New Castle County in northern Delaware...
Chester County in southeastern Pennsylvania...
* Until 615 PM EDT.
* At 537 PM EDT, severe thunderstorms were located along a line
extending from Honey Brook to near Richardsmere, moving east at 30
mph.
HAZARD...60 mph wind gusts and nickel size hail.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
* Locations impacted include...
West Chester, Coatesville, Downingtown, Kennett Square, Oxford,
Parkesburg, West Grove, Honey Brook, Elverson, Homeville, Glen Roy,
Cochranville, North Star, Pughtown, Mount Vernon, Marshallton, Pike
Creek, Lionville-Marchwood, Glenmoore and Chester Springs.
This includes Pennsylvania Turnpike between mile markers 300 and 316.
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 3976 7606 3981 7603 3983 7604 3983 7602
3987 7599 3992 7600 3994 7598 3995 7600
4004 7593 4012 7593 4017 7582 4018 7555
3972 7570 3972 7612
TIME...MOT...LOC 2137Z 264DEG 28KT 4009 7591 3972 7611
HAIL...0.88IN
WIND...60MPH
$$
Fitzsimmons1 follow-up statement
559
WWUS51 KPHI 172158
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
558 PM EDT Mon Aug 17 2020
DEC003-PAC029-172215-
/O.CON.KPHI.SV.W.0239.000000T0000Z-200817T2215Z/
New Castle DE-Chester PA-
558 PM EDT Mon Aug 17 2020
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM EDT
FOR NORTHWESTERN NEW CASTLE AND CHESTER COUNTIES...
At 556 PM EDT, severe thunderstorms were located along a line
extending from near Glenmoore to near Calvert, moving east at 25 mph.
HAZARD...60 mph wind gusts and nickel size hail.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
Locations impacted include...
West Chester, Coatesville, Downingtown, Kennett Square, Oxford,
Parkesburg, West Grove, Honey Brook, Elverson, Homeville, Glen Roy,
Cochranville, North Star, Pughtown, Mount Vernon, Marshallton, Pike
Creek, Lionville-Marchwood, Glenmoore and Chester Springs.
This includes Pennsylvania Turnpike between mile markers 300 and 316.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Protecting yourself from immediate threats to life and safety shall
take priority. Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.
For your protection move to an interior room on the lowest floor of a
building.
Frequent cloud to ground lightning is occurring with these storms.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.
Torrential rainfall is occurring with these storms, and may lead to
flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 3976 7606 3981 7603 3983 7604 3983 7602
3987 7599 3992 7600 3994 7598 3995 7600
4004 7593 4012 7593 4017 7582 4018 7555
3972 7570 3972 7612
TIME...MOT...LOC 2156Z 263DEG 22KT 4010 7581 3973 7602
HAIL...0.88IN
WIND...60MPH
$$
FitzsimmonsThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 16, 10:52 PM EDT | Coastal Flood Statement | PHI | Sussex | 4 hr |
| Aug 17, 5:08 AM EDT | Coastal Flood Advisory | PHI | Kent, New Castle, Sussex | 23 hr |
| Aug 17, 10:44 AM EDT | Rip Current Statement | PHI | Sussex | 11 hr |
| Aug 17, 6:16 PM EDT | Severe Thunderstorm Warning | PHI | New Castle | 16 min |
Nearby
Severe Thunderstorm Warnings in Delaware, 2020Severe Thunderstorm Warnings in Pennsylvania, 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.