Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2018
Severe Thunderstorm Warning 74, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 13, 2018, 7:42 PM EDT for Chester County, Pennsylvania. It was in force for 48 min. 1 report 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 13, 2018, 7:42 PM EDT (23:42 UTC)
- Expired
- Aug 13, 2018, 8:30 PM EDT
- In force
- 48 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
County Chester County, PA
The radar
The Dover AFB radar (KDOX), 121 km from the middle of the area, began a volume at 23:42 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 13, 7:45 PM EDT | TSTM WND DMG | Oxford, PA | A FEW TREES DOWN BETWEEN OXFORD AND MOUNT VERNON. 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, 11.7 hours before the alert went out and 154 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
- 714 J/kg
- Mixed-layer CIN
- -15 J/kg
- Mixed-layer LCL
- 644 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 19 m²/s²
- 0-3 km storm-relative helicity
- 27 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
455
WUUS51 KPHI 132342
SVRPHI
PAC029-140030-
/O.NEW.KPHI.SV.W.0074.180813T2342Z-180814T0030Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
742 PM EDT MON AUG 13 2018
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
Southwestern Chester County in southeastern Pennsylvania...
* Until 830 PM EDT.
* At 742 PM EDT, a severe thunderstorm was located over Glen Roy, or
14 miles north of Havre De Grace, moving northeast at 25 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
* This severe thunderstorm will be near...
Mount Vernon around 750 PM EDT.
Oxford around 755 PM EDT.
Homeville around 800 PM EDT.
West Grove and Cochranville around 810 PM EDT.
Parkesburg around 820 PM EDT.
Kennett Square around 825 PM EDT.
Coatesville around 830 PM EDT.
Other locations impacted by this severe thunderstorm include
Avondale, Toughkenamon, Atglen, Christiana, South Coatesville and
Modena.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
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 3973 7610 3974 7610 3976 7606 3981 7603
3983 7604 3987 7599 3992 7600 3994 7598
3995 7600 4004 7594 3987 7566 3972 7592
3972 7608 3973 7612
TIME...MOT...LOC 2342Z 220DEG 20KT 3974 7603
HAIL...<.75IN
WIND...60MPH
$$
Gorse2 follow-up statements
485
WWUS51 KPHI 140003
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
803 PM EDT MON AUG 13 2018
PAC029-140030-
/O.CON.KPHI.SV.W.0074.000000T0000Z-180814T0030Z/
Chester PA-
803 PM EDT MON AUG 13 2018
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 830 PM EDT
FOR SOUTHWESTERN CHESTER COUNTY...
At 803 PM EDT, a severe thunderstorm was located over Cochranville,
or 15 miles west of West Chester, moving northeast at 25 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
This severe storm will be near...
Parkesburg around 815 PM EDT.
Coatesville around 825 PM EDT.
Other locations impacted by this severe thunderstorm include
Avondale, Toughkenamon, Atglen, Christiana, South Coatesville and
Modena.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
In addition to damaging winds, frequent cloud to ground lightning is
occurring with this storm. Move indoors immediately. Remember, if
you can hear thunder, you are close enough to be struck by lightning.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 3977 7591 3978 7594 3978 7596 3981 7603
3983 7604 3987 7599 3992 7600 3994 7598
3995 7600 4004 7594 3987 7566 3976 7585
3977 7587
TIME...MOT...LOC 0003Z 207DEG 20KT 3989 7589
HAIL...<.75IN
WIND...60MPH
$$
Gorse797
WWUS51 KPHI 140027
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
827 PM EDT MON AUG 13 2018
PAC029-140036-
/O.EXP.KPHI.SV.W.0074.000000T0000Z-180814T0030Z/
Chester PA-
827 PM EDT MON AUG 13 2018
...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN CHESTER COUNTY
WILL EXPIRE AT 830 PM EDT...
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 will be allowed to expire. However heavy rain
is still possible.
LAT...LON 3977 7591 3978 7594 3978 7596 3981 7603
3983 7604 3987 7599 3992 7600 3994 7598
3995 7600 4004 7594 3987 7566 3976 7585
3977 7587
TIME...MOT...LOC 0026Z 220DEG 20KT 3998 7579
$$
GorseThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 12, 10:08 PM EDT | Flash Flood Watch | PHI | Berks, Bucks, Carbon, Chester, Delaware, Lehigh and 4 more | 24 hr |
| Aug 13, 4:42 AM EDT | Areal Flood Advisory | PHI | Berks | 4 hr |
| Aug 13, 5:12 AM EDT | Areal Flood Advisory | PHI | Chester | 103 min |
| Aug 13, 6:24 AM EDT | Areal Flood Advisory | PHI | Berks, Chester, Delaware, Montgomery | 4 hr |
| Aug 13, 6:50 AM EDT | Flash Flood Warning | PHI | Berks, Chester, Delaware, Montgomery | 6 hr |
| Aug 13, 8:03 AM EDT | Areal Flood Advisory | PHI | Delaware, Montgomery, Philadelphia | 4 hr |
| Aug 13, 8:43 AM EDT | Flash Flood Warning | PHI | Bucks, Delaware, Lehigh, Montgomery, Northampton, Philadelphia | 4 hr |
| Aug 13, 9:21 AM EDT | River Flood Warning | PHI | Chester | 10 hr |
| Aug 13, 10:40 AM EDT | Areal Flood Advisory | PHI | Carbon, Monroe, Northampton | 42 min |
| Aug 13, 11:05 AM EDT | River Flood Warning | PHI | Chester, Delaware | 30 hr |
| Aug 13, 11:21 AM EDT | Areal Flood Warning | PHI | Carbon, Monroe, Northampton | 4 hr |
| Aug 13, 12:14 PM EDT | River Flood Warning | PHI | Berks, Montgomery | 23 hr |
| Aug 13, 12:14 PM EDT | River Flood Warning | PHI | Montgomery | 28 hr |
| Aug 13, 12:14 PM EDT | River Flood Warning | PHI | Chester, Montgomery, Philadelphia | 52 hr |
| Aug 13, 12:37 PM EDT | Areal Flood Warning | PHI | Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 1 more | 18 hr |
| Aug 13, 3:07 PM EDT | River Flood Warning | PHI | Montgomery | 6 hr |
| Aug 13, 4:57 PM EDT | Areal Flood Advisory | PHI | Carbon, Monroe, Northampton | 3 hr |
| Aug 13, 5:09 PM EDT | River Flood Warning | PHI | Montgomery, Philadelphia | 31 hr |
| Aug 13, 7:27 PM EDT | Areal Flood Warning | PHI | Carbon, Northampton | 7 hr |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 2018Every severe thunderstorm warning in 2018
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.