Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 155, NWS Philadelphia/Mount Holly

July 29, 2009Berks County, Lehigh County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 29, 2009, 5:28 PM EDT for Berks County, Lehigh County, Northampton County, Pennsylvania. It was in force for 40 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
Jul 29, 2009, 5:28 PM EDT (21:28 UTC)
Expired
Jul 29, 2009, 6:08 PM EDT
In force
40 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Berks County, PA, Lehigh County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 121 km from the middle of the area, began a volume at 21:29 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
Jul 29, 12:49 PM EDTSevere Thunderstorm WatchSPC8 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 9.5 hours before the alert went out and 129 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 2009-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1577 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 2009-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 56 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
1577 J/kg
Mixed-layer CIN
-35 J/kg
Mixed-layer LCL
745 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
56 m²/s²
0-3 km storm-relative helicity
86 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 292128
SVRPHI
PAC011-077-095-292230-
/O.NEW.KPHI.SV.W.0155.090729T2128Z-090729T2230Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
528 PM EDT WED JUL 29 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EAST CENTRAL BERKS COUNTY IN EASTERN PENNSYLVANIA...
  LEHIGH COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF ALLENTOWN...
  SOUTHERN NORTHAMPTON COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF BETHLEHEM...

* UNTIL 630 PM EDT

* AT 527 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED 10
  MILES SOUTHWEST OF ZIONSVILLE...OR 15 MILES EAST OF READING...AND
  MOVING NORTH AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  ANCIENT OAKS AND 6 MILES WEST OF ZIONSVILLE AROUND 545 PM EDT...
  EMMAUS AROUND 550 PM EDT...
  CLAUSSVILLE AROUND 555 PM EDT...
  COFFEETOWN AND ALLENTOWN AROUND 600 PM EDT...
  NEFFS AND SCHNECKSVILLE AROUND 605 PM EDT...
  NORTHAMPTON AROUND 610 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...CONTINUOUS CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY LIGHTNING IS ONE OF NATURES GREATEST KILLERS.
REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE
STRUCK BY LIGHTNING.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT
WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 4077 7563 4067 7526 4044 7554 4034 7564
      4039 7579
TIME...MOT...LOC 2128Z 202DEG 27KT 4041 7566

$$

EBERWINE
2 follow-up statements
000 
WWUS51 KPHI 292154
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
554 PM EDT WED JUL 29 2009

PAC011-292203-
/O.CAN.KPHI.SV.W.0155.000000T0000Z-090729T2230Z/
BERKS PA-
554 PM EDT WED JUL 29 2009

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL BERKS COUNTY IS
CANCELLED...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT
WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

A TREE WAS REPORTED DOWN ACROSS ROUTES ALONG ROUTES 662 AND 422. 

LAT...LON 4054 7542 4063 7568 4077 7563 4067 7526
      4044 7554
TIME...MOT...LOC 2153Z 202DEG 27KT 4064 7553

$$

PAC077-095-292230-
/O.CON.KPHI.SV.W.0155.000000T0000Z-090729T2230Z/
LEHIGH PA-NORTHAMPTON PA-
554 PM EDT WED JUL 29 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM EDT
FOR SOUTHWESTERN NORTHAMPTON AND NORTHEASTERN LEHIGH COUNTIES...

AT 552 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
LOCATED NEAR COFFEETOWN...OR NEAR ALLENTOWN...MOVING NORTH AT 30 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  NORTHAMPTON...COPLAY...NORTH CATASAUQUA AND CATASAUQUA BY 600 PM
  EDT...
  6 MILES EAST OF WALNUTPORT...7 MILES WEST OF STEUBEN AND 7 MILES
  EAST OF SLATINGTON BY 605 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT
WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 4054 7542 4063 7568 4077 7563 4067 7526
      4044 7554
TIME...MOT...LOC 2153Z 202DEG 27KT 4064 7553

$$

EBERWINE
000 
WWUS51 KPHI 292208
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
608 PM EDT WED JUL 29 2009

PAC077-095-292218-
/O.CAN.KPHI.SV.W.0155.000000T0000Z-090729T2230Z/
LEHIGH PA-NORTHAMPTON PA-
608 PM EDT WED JUL 29 2009

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN NORTHAMPTON AND
NORTHEASTERN LEHIGH COUNTIES IS CANCELLED...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT
WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE THROUGH THE AREA OVER 
THE NEXT HOUR.

LAT...LON 4054 7542 4063 7568 4077 7563 4067 7526
      4044 7554
TIME...MOT...LOC 2208Z 202DEG 27KT 4074 7548

$$

EBERWINE

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 29, 10:15 AM EDTFlash Flood WatchPHIBerks, Delaware, Lehigh, Northampton, Philadelphia17 hr
Jul 29, 11:48 AM EDTSevere Thunderstorm WarningPHIBucks, Chester, Montgomery72 min
Jul 29, 12:12 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton78 min
Jul 29, 1:51 PM EDTFlash Flood WarningPHICarbon, Monroe9 hr
Jul 29, 1:56 PM EDTSevere Thunderstorm WarningPHIMonroe64 min
Jul 29, 2:04 PM EDTSevere Thunderstorm WarningPHIMonroe56 min
Jul 29, 2:11 PM EDTTornado WarningPHICarbon, Monroe34 min
Jul 29, 2:32 PM EDTFlash Flood WarningPHIMonroe6 hr
Jul 29, 5:09 PM EDTSevere Thunderstorm WarningPHIBucks66 min
Jul 29, 5:55 PM EDTAreal Flood AdvisoryPHIBucks, Delaware, Montgomery, Philadelphia4 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.