Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 112, NWS Philadelphia/Mount Holly

June 30, 2009Berks County, Chester County, Montgomery County, Pennsylvania; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 30, 2009, 2:31 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania; Cecil County, Maryland. It was in force for 44 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
Jun 30, 2009, 2:31 PM EDT (18:31 UTC)
Expired
Jun 30, 2009, 3:15 PM EDT
In force
44 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Cecil County, MD, Berks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Dover AFB radar (KDOX), 117 km from the middle of the area, began a volume at 18:30 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

TimeReportWhereRemark
Jun 30, 2:42 PM EDTTSTM WND DMG4 Nne Cedarville, PATREE DOWN ON WIRES IN UPPER POTTSGROVE

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

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

IssuedProductOfficeLasted
Jun 30, 11:37 AM EDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 6.5 hours before the alert went out and 39 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 2009-06-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 161 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 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 2009-06-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 53 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
161 J/kg
Mixed-layer CIN
-86 J/kg
Mixed-layer LCL
1704 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
53 m²/s²
0-3 km storm-relative helicity
95 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.8

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 301831
SVRPHI
MDC015-PAC011-029-091-301915-
/O.NEW.KPHI.SV.W.0112.090630T1831Z-090630T1915Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
231 PM EDT TUE JUN 30 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN BERKS COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF READING...
  CECIL COUNTY IN NORTHEAST MARYLAND...
  THIS INCLUDES THE CITY OF ELKTON...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...
  WEST CENTRAL MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 315 PM EDT

* AT 228 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING PENNY SIZE
  HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
  LOCATED ALONG A LINE EXTENDING FROM BIRDSBORO TO 18 MILES SOUTHWEST
  OF CHARLESTOWN...OR ALONG A LINE EXTENDING FROM 6 MILES SOUTHEAST
  OF READING TO 22 MILES EAST OF BALTIMORE...AND MOVING EAST AT 45
  MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  COCHRANVILLE...FARMINGTON...CALVERT AND PARKESBURG AROUND 235 PM
  EDT...
  GLENMOORE...CEDARVILLE...ZION AND LOMBARD AROUND 240 PM EDT...
  GILBERTSVILLE AND PUGHTOWN AROUND 245 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM EDT
TUESDAY EVENING FOR NORTHWESTERN NEW JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3975 7610 3987 7601 4011 7595 4014 7590
      4023 7602 4036 7597 4037 7567 4015 7529
      3974 7580 3938 7579 3938 7603 3941 7605
      3945 7600 3946 7602 3956 7598 3955 7609
      3972 7623
TIME...MOT...LOC 1830Z 259DEG 41KT 4029 7581 3939 7620

$$

NIERENBERG
1 follow-up statement
000 
WWUS51 KPHI 301903
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
303 PM EDT TUE JUN 30 2009

PAC011-301913-
/O.CAN.KPHI.SV.W.0112.000000T0000Z-090630T1915Z/
BERKS PA-
303 PM EDT TUE JUN 30 2009

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN BERKS COUNTY IS
CANCELLED...

THE LINE OF STORMS HAS MOVED EAST OF THE AREA.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM EDT
TUESDAY EVENING FOR NORTHWESTERN NEW JERSEY AND EASTERN PENNSYLVANIA.

LAT...LON 3982 7584 4001 7571 4010 7574 4024 7570
      4030 7557 4015 7529 3974 7580 3938 7579
      3939 7603 3941 7604 3945 7600 3946 7602
      3956 7598 3955 7609 3968 7608 3975 7610
TIME...MOT...LOC 1903Z 259DEG 41KT 4020 7540 3949 7601

$$

MDC015-PAC029-091-301915-
/O.CON.KPHI.SV.W.0112.000000T0000Z-090630T1915Z/
CECIL MD-CHESTER PA-MONTGOMERY PA-
303 PM EDT TUE JUN 30 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM EDT
FOR CENTRAL MONTGOMERY...CHESTER AND CECIL COUNTIES...

AT 302 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING
WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM EVANSBURG TO 6 MILES WEST OF HOLLYWOOD BEACH...OR
ALONG A LINE EXTENDING FROM 19 MILES NORTHEAST OF WEST CHESTER TO 13
MILES SOUTHWEST OF ELKTON...MOVING EAST AT 45 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  CECILTON...HOLLYWOOD BEACH...WEST NORRITON AND KING OF PRUSSIA BY
  310 PM EDT...
  CHESAPEAKE CITY...CAYOTS...BRANTWOOD AND NORRISTOWN BY 315 PM
  EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM EDT
TUESDAY EVENING FOR NORTHWESTERN NEW JERSEY AND EASTERN PENNSYLVANIA.

IF YOU SEE THREATENING WEATHER, HEAD INDOORS IMMEDIATELY.

&&

LAT...LON 3982 7584 4001 7571 4010 7574 4024 7570
      4030 7557 4015 7529 3974 7580 3938 7579
      3939 7603 3941 7604 3945 7600 3946 7602
      3956 7598 3955 7609 3968 7608 3975 7610
TIME...MOT...LOC 1903Z 259DEG 41KT 4020 7540 3949 7601

$$

TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 30, 1:15 PM EDTSevere Thunderstorm WarningPHIBerks75 min
Jun 30, 2:51 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery54 min
Jun 30, 3:12 PM EDTSevere Thunderstorm WarningPHIBucks63 min
Jun 30, 3:13 PM EDTFlash Flood WarningPHIBucks, Montgomery114 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2009Severe Thunderstorm Warnings in Maryland, 2009Every severe thunderstorm warning in 2009

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.