Alert archive / Pennsylvania / Tornado Warnings in 2015

Tornado Warning 10, NWS Philadelphia/Mount Holly

October 9, 2015Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this tornado warning at Oct 9, 2015, 4:47 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 28 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
Oct 9, 2015, 4:47 PM EDT (20:47 UTC)
Expired
Oct 9, 2015, 5:15 PM EDT
In force
28 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 91 km from the middle of the area, began a volume at 20:47 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
Oct 9, 3:34 PM EDTSevere Thunderstorm WatchSPC4 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 8.8 hours before the alert went out and 214 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, Washington/Dulle, VA at 12:00Z on 2015-10-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 43 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, Washington/Dulle, VA at 12:00Z on 2015-10-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 114 square meters per square second.193958Sfc1 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
43 J/kg
Mixed-layer CIN
-181 J/kg
Mixed-layer LCL
1203 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
114 m²/s²
0-3 km storm-relative helicity
126 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.

670 
WFUS51 KPHI 092047
TORPHI
PAC029-091-092115-
/O.NEW.KPHI.TO.W.0010.151009T2047Z-151009T2115Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
447 PM EDT FRI OCT 9 2015

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ  HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHEASTERN CHESTER COUNTY IN SOUTHEASTERN PENNSYLVANIA...
  SOUTHWESTERN MONTGOMERY COUNTY IN SOUTHEASTERN PENNSYLVANIA...

* UNTIL 515 PM EDT
    
* AT 446 PM EDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
  CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED
  OVER ROYERSFORD...OR 14 MILES NORTH OF WEST CHESTER...AND MOVING
  EAST AT 45 MPH.

* LOCATIONS IMPACTED INCLUDE...
  NORRISTOWN...PHOENIXVILLE...WEST NORRITON...EAST NORRITON...
  CONSHOHOCKEN...COLLEGEVILLE...ROYERSFORD...TRAPPE...PLYMOUTH
  MEETING...KING OF PRUSSIA...SKIPPACK...BRIDGEPORT...SPRING CITY...
  WEST CONSHOHOCKEN...EAGLEVILLE...EVANSBURG...SPRING HOUSE...
  TROOPER...BLUE BELL AND AUDUBON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE LOWEST
FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF YOU ARE IN A MOBILE
HOME OR OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND
PROTECT YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4016 7559 4023 7557 4019 7522 4003 7528
TIME...MOT...LOC 2046Z 290DEG 37KT 4016 7551 

$$

SZATKOWSKI
1 follow-up statement
256 
WWUS51 KPHI 092110
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
510 PM EDT FRI OCT 9 2015

PAC029-091-092118-
/O.EXP.KPHI.TO.W.0010.000000T0000Z-151009T2115Z/
CHESTER PA-MONTGOMERY PA-
510 PM EDT FRI OCT 9 2015

...THE TORNADO WARNING FOR NORTHEASTERN CHESTER AND SOUTHWESTERN
MONTGOMERY COUNTIES WILL EXPIRE AT 515 PM EDT...
    
THE TORNADIC THUNDERSTORM WHICH PROMPTED THE WARNING HAS WEAKENED. 
THEREFORE THE WARNING WILL BE ALLOWED TO EXPIRE.

LAT...LON 4016 7559 4023 7557 4019 7522 4003 7528
TIME...MOT...LOC 2106Z 290DEG 37KT 4016 7551 

$$

SZATKOWSKI

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 9, 2:45 PM EDTSpecial Weather StatementPHIBerks, Carbon, Lehigh, Monroe, Northampton90 min
Oct 9, 3:17 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Monroe, Northampton58 min
Oct 9, 4:01 PM EDTSevere Thunderstorm WarningPHIBerks, Chester44 min
Oct 9, 4:39 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Delaware, Montgomery, Philadelphia51 min
Oct 9, 5:25 PM EDTSpecial Weather StatementPHIBucks, Montgomery65 min
Oct 9, 5:41 PM EDTSpecial Weather StatementPHIPhiladelphia49 min

Nearby

Tornado Warnings in Pennsylvania, 2015Every tornado warning in 2015Tornadoes 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.