Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 105, NWS Philadelphia/Mount Holly

September 12, 2013Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 12, 2013, 5:47 PM EDT for Chester County, Delaware County, Pennsylvania. It was in force for 58 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
Sep 12, 2013, 5:47 PM EDT (21:47 UTC)
Expired
Sep 12, 2013, 6:45 PM EDT
In force
58 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Chester County, PA, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 107 km from the middle of the area, began a volume at 21:49 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Sep 12, 2:50 PM EDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 9.8 hours before the alert went out and 70 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, Phillips Aaf/Abe, MD at 12:00Z on 2013-09-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1009 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, Phillips Aaf/Abe, MD at 12:00Z on 2013-09-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 35 square meters per square second.1939Sfc1 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
1009 J/kg
Mixed-layer CIN
-79 J/kg
Mixed-layer LCL
970 m above ground
0-6 km bulk shear
12 kt
0-1 km storm-relative helicity
35 m²/s²
0-3 km storm-relative helicity
39 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

174 
WUUS51 KPHI 122147
SVRPHI
PAC029-045-122245-
/O.NEW.KPHI.SV.W.0105.130912T2147Z-130912T2245Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
547 PM EDT THU SEP 12 2013

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WESTERN DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 645 PM EDT

* AT 545 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM. THE STORM WAS NEAR PARKESBURG...MOVING EAST AT
  30 MPH. THIS STORM IS CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH. 

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  COATESVILLE AND WEST GROVE AROUND 555 PM EDT...
  GLENMOORE AND KENNETT SQUARE AROUND 605 PM EDT...
  DOWNINGTOWN AND MARSHALLTON AROUND 610 PM EDT...
  LIONVILLE AROUND 615 PM EDT...
  WEST CHESTER AND CHESTER SPRINGS AROUND 620 PM EDT...
  WESTTOWN AND ELAM AROUND 625 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE WINDS OF MORE THAN 57 MPH...OR HAIL ONE
INCH OR LARGER.

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS SEVERE
THUNDERSTORM. WHEN THUNDER ROARS...MOVE INDOORS! REMEMBER...IF YOU
CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
THURSDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3988 7599 3991 7601 4013 7591 4014 7589
      4016 7553 4015 7552 4016 7550 4014 7551
      4013 7547 4009 7546 4009 7542 4006 7539
      3980 7541 3984 7551 3984 7562 3981 7570
      3981 7605
TIME...MOT...LOC 2147Z 266DEG 25KT 3998 7591

$$

MEOLA
2 follow-up statements
080 
WWUS51 KPHI 122217
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
617 PM EDT THU SEP 12 2013

PAC029-045-122245-
/O.CON.KPHI.SV.W.0105.000000T0000Z-130912T2245Z/
DELAWARE PA-CHESTER PA-
617 PM EDT THU SEP 12 2013

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM EDT
FOR EASTERN CHESTER AND WESTERN DELAWARE COUNTIES...

AT 614 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR WEST CHESTER...MOVING
EAST AT 35 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
MALVERN AND PAOLI AROUND 625 PM EDT...
GRADYVILLE AND DEVON-BERWYN AROUND 630 PM EDT...
NEWTOWN SQUARE AND LINWOOD AROUND 635 PM EDT...

LAT...LON 4014 7568 4015 7552 4016 7550 4014 7551
      4013 7550 4013 7547 4009 7546 4009 7542
      4006 7539 3980 7541 3984 7551 3984 7562
      3981 7582
TIME...MOT...LOC 2217Z 268DEG 30KT 3998 7560

$$

FORECASTER: AMC
174 
WWUS51 KPHI 122232
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
632 PM EDT THU SEP 12 2013

PAC029-045-122241-
/O.CAN.KPHI.SV.W.0105.000000T0000Z-130912T2245Z/
DELAWARE PA-CHESTER PA-
632 PM EDT THU SEP 12 2013

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN CHESTER AND WESTERN
DELAWARE COUNTIES IS CANCELLED...

THE STORM HAS WEAKENED TO BELOW SEVERE LIMITS...THEREFORE THE SEVERE
THUNDERSTORM WARNING HAS BEEN CANCELLED.

LAT...LON 4014 7568 4015 7552 4016 7550 4014 7551
      4013 7550 4013 7547 4009 7546 4009 7542
      4006 7539 3980 7541 3984 7551 3984 7562
      3981 7582
TIME...MOT...LOC 2231Z 268DEG 30KT 3998 7545

$$

FORECASTER: AMC

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 12, 7:38 AM EDTAreal Flood AdvisoryPHIBucks3 hr
Sep 12, 2:26 PM EDTSpecial Weather StatementPHICarbon, Monroe64 min
Sep 12, 3:43 PM EDTSpecial Weather StatementPHIBerks62 min
Sep 12, 4:21 PM EDTSpecial Weather StatementPHIBerks, Carbon, Lehigh, Monroe, Northampton84 min
Sep 12, 4:40 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Carbon, Lehigh, Monroe, Montgomery and 1 more95 min
Sep 12, 6:07 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton68 min
Sep 12, 6:43 PM EDTSpecial Weather StatementPHIPhiladelphia62 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2013Every severe thunderstorm warning in 2013

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.