Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 15, NWS Philadelphia/Mount Holly

May 27, 2015Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 27, 2015, 4:36 PM EDT for Chester County, Pennsylvania. It was in force for 39 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
May 27, 2015, 4:36 PM EDT (20:36 UTC)
Expired
May 27, 2015, 5:15 PM EDT
In force
39 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 124 km from the middle of the area, began a volume at 20:37 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
May 27, 12:54 PM EDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 8.6 hours before the alert went out and 53 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 2015-05-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 428 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 2015-05-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 78 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
428 J/kg
Mixed-layer CIN
-59 J/kg
Mixed-layer LCL
589 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
78 m²/s²
0-3 km storm-relative helicity
81 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

Open this sounding in Storm Lab

The text

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

728 
WUUS51 KPHI 272036
SVRPHI
PAC029-272115-
/O.NEW.KPHI.SV.W.0015.150527T2036Z-150527T2115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
436 PM EDT WED MAY 27 2015

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ  HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CHESTER COUNTY IN SOUTHEASTERN PENNSYLVANIA...

* UNTIL 515 PM EDT

* AT 436 PM EDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
  CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS 
  STORM WAS LOCATED NEAR WEST GROVE...MOVING NORTHEAST AT 35 MPH.

* LOCATIONS IMPACTED INCLUDE...
  WEST CHESTER...PHOENIXVILLE...COATESVILLE...DOWNINGTOWN...KENNETT
  SQUARE...OXFORD...PARKESBURG...WEST GROVE...MARSHALLTON...
  HOMEVILLE...COCHRANVILLE...GLENMOORE...CHESTER SPRINGS...
  PUGHTOWN...PAOLI...LIONVILLE-MARCHWOOD...LIONVILLE...WEST GOSHEN...
  MALVERN AND SOUTH COATESVILLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS...DEADLY LIGHTNING AND 
VERY HEAVY RAIN. FOR YOUR PROTECTION...MOVE TO AN INTERIOR ROOM ON 
THE LOWEST FLOOR OF YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS 
QUICKLY SO DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 3987 7599 3990 7599 4022 7563 4004 7542
      3973 7589 3983 7602 3985 7602
TIME...MOT...LOC 2036Z 229DEG 31KT 3984 7589 

$$

IOVINO
1 follow-up statement
195 
WWUS51 KPHI 272056
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
456 PM EDT WED MAY 27 2015

PAC029-272115-
/O.CON.KPHI.SV.W.0015.000000T0000Z-150527T2115Z/
CHESTER PA-
456 PM EDT WED MAY 27 2015

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM EDT
FOR CENTRAL CHESTER COUNTY...

AT 455 PM EDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE
OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS 
LOCATED OVER MARSHALLTON...MOVING NORTHEAST AT 35 MPH.

LOCATIONS IMPACTED INCLUDE...
WEST CHESTER...PHOENIXVILLE...COATESVILLE...DOWNINGTOWN...KENNETT
SQUARE...PARKESBURG...CHESTER SPRINGS...MARSHALLTON...GLENMOORE...
PUGHTOWN...PAOLI...LIONVILLE-MARCHWOOD...LIONVILLE...WEST GOSHEN...
MALVERN...SOUTH COATESVILLE...MODENA...THORNDALE...TOUGHKENAMON AND
DEVON-BERWYN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS...DEADLY LIGHTNING AND 
VERY HEAVY RAIN. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE 
LOWEST FLOOR OF YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS 
QUICKLY SO DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 4022 7563 4004 7542 3982 7576 3996 7592
TIME...MOT...LOC 2055Z 229DEG 31KT 3995 7572 

$$

IOVINO

The office that day

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

IssuedProductOfficeCountiesLasted
May 27, 2:23 PM EDTSpecial Weather StatementPHILebanon22 min
May 27, 2:48 PM EDTSpecial Weather StatementPHICarbon27 min
May 27, 2:53 PM EDTSpecial Weather StatementPHIBerks, Lehigh52 min
May 27, 3:06 PM EDTSpecial Weather StatementPHICarbon, Monroe54 min
May 27, 3:13 PM EDTSpecial Weather StatementPHIBerks62 min
May 27, 3:53 PM EDTSpecial Weather StatementPHIMonroe37 min
May 27, 4:26 PM EDTSpecial Weather StatementPHIChester64 min
May 27, 5:07 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery53 min
May 27, 5:25 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia44 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2015Every severe thunderstorm warning in 2015

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.