Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 76, NWS Philadelphia/Mount Holly

August 13, 2018Bucks County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 13, 2018, 9:00 PM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 60 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 13, 2018, 9:00 PM EDT (01:00 UTC)
Expired
Aug 13, 2018, 10:00 PM EDT
In force
60 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Bucks County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 53 km from the middle of the area, began a volume at 01:00 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

Brookhaven, NY (KOKX), launched 00:00Z, 1.0 hours before the alert went out and 202 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-pSkew-T log-p diagram, Brookhaven, NY at 00:00Z on 2018-08-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 399 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 00:00Z on 2018-08-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
399 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
664 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
82 m²/s²
Significant tornado parameter
0.1
Supercell composite
2.4

Open this sounding in Storm Lab

The text

As transmitted.

757 
WUUS51 KPHI 140100
SVRPHI
PAC017-091-101-140200-
/O.NEW.KPHI.SV.W.0076.180814T0100Z-180814T0200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
900 PM EDT MON AUG 13 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southeastern Montgomery County in southeastern Pennsylvania...
  Southeastern Bucks County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...

* Until 1000 PM EDT.

* At 859 PM EDT, a severe thunderstorm was located over Germantown, 
  or near Philadelphia, moving northeast at 20 mph. It will not take 
  as much wind to down some trees due to the saturated ground.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  Philadelphia, Bensalem, Yeadon, Burlington, Bristol, Conshohocken,
  Palmyra, Hatboro, Ambler, Jenkintown, Narberth, Rockledge,
  Tullytown, Abington, Langhorne, Bryn Athyn, Ivyland, Wissinoming,
  Feasterville-Trevose and Morris Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4012 7481 4013 7482 4010 7484 4008 7487
      4007 7494 4001 7502 3994 7525 3996 7525
      3997 7527 4004 7533 4031 7510 4012 7480
TIME...MOT...LOC 0059Z 235DEG 18KT 4004 7521 

HAIL...<.75IN
WIND...60MPH
 
$$

Gorse
3 follow-up statements
534 
WWUS51 KPHI 140121
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
921 PM EDT MON AUG 13 2018

PAC017-091-101-140200-
/O.CON.KPHI.SV.W.0076.000000T0000Z-180814T0200Z/
Montgomery PA-Bucks PA-Philadelphia PA-
921 PM EDT MON AUG 13 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1000 PM EDT
FOR SOUTHEASTERN MONTGOMERY...SOUTHEASTERN BUCKS AND NORTHERN
PHILADELPHIA COUNTIES...

At 920 PM EDT, a severe thunderstorm was located over Abington, or 8 
miles north of Philadelphia, moving northeast at 20 mph. It will not 
take   as much wind to down some trees due to the saturated ground.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Philadelphia, Bensalem, Burlington, Bristol, Hatboro, Ambler,
Jenkintown, Rockledge, Tullytown, Abington, Langhorne, Bryn Athyn,
Ivyland, Feasterville-Trevose, Willow Grove, Northeast Philadelphia,
Feasterville, Richboro, Andalusia and Holmesburg.

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.

&&

LAT...LON 4012 7481 4013 7482 4010 7484 4008 7487
      4007 7494 4004 7501 4002 7514 4006 7519
      4008 7522 4012 7526 4031 7510 4012 7480
TIME...MOT...LOC 0120Z 223DEG 18KT 4012 7511 

HAIL...<.75IN
WIND...60MPH
 
$$

Gorse
174 
WWUS51 KPHI 140147
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
947 PM EDT MON AUG 13 2018

PAC017-091-101-140200-
/O.CON.KPHI.SV.W.0076.000000T0000Z-180814T0200Z/
Montgomery PA-Bucks PA-Philadelphia PA-
947 PM EDT MON AUG 13 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1000 PM EDT
FOR EAST CENTRAL MONTGOMERY...SOUTHEASTERN BUCKS AND NORTHEASTERN
PHILADELPHIA COUNTIES...

At 947 PM EDT, a severe thunderstorm was located over Newtown, or 10 
miles west of Trenton, moving northeast at 30 mph. It will not take 
as much wind to down some trees due to the saturated ground.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Philadelphia, Bensalem, Hatboro, Langhorne, Bryn Athyn, Ivyland,
Richboro, Feasterville-Trevose, Willow Grove, Andalusia, Northeast
Philadelphia, Langhorn, Levittown, Feasterville, Horsham, Penndel,
Langhorne Manor, Hulmeville, Cornwells Heights-Eddington and
Churchville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4013 7482 4013 7484 4012 7487 4006 7499
      4007 7506 4011 7509 4016 7513 4022 7517
      4031 7510 4014 7483
TIME...MOT...LOC 0147Z 239DEG 25KT 4023 7496 

HAIL...<.75IN
WIND...60MPH
 
$$

Gorse
752 
WWUS51 KPHI 140154
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
954 PM EDT MON AUG 13 2018

PAC017-091-101-140204-
/O.EXP.KPHI.SV.W.0076.000000T0000Z-180814T0200Z/
Montgomery PA-Bucks PA-Philadelphia PA-
954 PM EDT MON AUG 13 2018

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL MONTGOMERY...
SOUTHEASTERN BUCKS AND NORTHEASTERN PHILADELPHIA COUNTIES WILL EXPIRE
AT 1000 PM EDT...
                
The storm which prompted the warning is weakening. Therefore, the 
warning will be allowed to expire. However locally gusty winds and 
heavy rain are still possible with this thunderstorm.

LAT...LON 4013 7482 4013 7484 4012 7487 4006 7499
      4007 7506 4011 7509 4016 7513 4022 7517
      4031 7510 4014 7483
TIME...MOT...LOC 0154Z 235DEG 18KT 4024 7493 

$$

Gorse

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 13, 8:13 PM EDTSpecial Weather StatementPHIMontgomery32 min
Aug 13, 8:16 PM EDTAreal Flood AdvisoryPHIChester, Delaware, Montgomery, Philadelphia3 hr
Aug 13, 8:51 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery54 min
Aug 13, 9:16 PM EDTSevere Thunderstorm WarningPHIBucks44 min
Aug 14, 12:50 PM EDTAreal Flood AdvisoryPHIBucks, Lehigh, Northampton4 hr
Aug 14, 3:22 PM EDTSpecial Weather StatementPHILehigh53 min
Aug 14, 3:58 PM EDTSpecial Weather StatementPHIMontgomery47 min

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.