Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 35, NWS Philadelphia/Mount Holly

May 29, 2009Berks County, Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 29, 2009, 3:28 PM EDT for Berks County, Chester County, Pennsylvania. It was in force for 62 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
May 29, 2009, 3:28 PM EDT (19:28 UTC)
Expired
May 29, 2009, 4:30 PM EDT
In force
62 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Berks County, PA, Chester County, PA

The radar

The Philadelphia radar (KDIX), 128 km from the middle of the area, began a volume at 19:29 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.

What was reported inside it

TimeReportWhereRemark
May 29, 3:57 PM EDTTSTM WND DMG2 N Parkesburg, PATREE LIMBS REPORTED DOWN IN SADSBURY.

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
May 29, 1:26 PM EDTSevere Thunderstorm WatchSPC8 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.5 hours before the alert went out and 68 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 2009-05-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4 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 2009-05-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 58 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
4 J/kg
Mixed-layer CIN
-283 J/kg
Mixed-layer LCL
620 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
58 m²/s²
0-3 km storm-relative helicity
139 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.

000 
WUUS51 KPHI 291928
SVRPHI
PAC011-029-292045-
/O.NEW.KPHI.SV.W.0035.090529T1928Z-090529T2045Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
328 PM EDT FRI MAY 29 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EXTREME SOUTH CENTRAL BERKS COUNTY IN EASTERN PENNSYLVANIA...
  NORTHWESTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 445 PM EDT

* AT 323 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED 18
  MILES WEST OF HONEY BROOK...OR NEAR LANCASTER...AND MOVING EAST AT
  25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  HONEY BROOK AROUND 405 PM EDT...
  COATESVILLE AROUND 415 PM EDT...
  GLENMOORE AROUND 420 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

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

&&

LAT...LON 4002 7597 4003 7595 4011 7595 4014 7590
      4017 7594 4018 7594 4021 7571 3990 7570
      3992 7600 3996 7600
TIME...MOT...LOC 1926Z 270DEG 22KT 4004 7622

$$

KRUZDLO
1 follow-up statement
000 
WWUS51 KPHI 292030
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
430 PM EDT FRI MAY 29 2009

PAC011-029-292040-
/O.CAN.KPHI.SV.W.0035.000000T0000Z-090529T2045Z/
CHESTER PA-BERKS PA-
430 PM EDT FRI MAY 29 2009

...THE SEVERE THUNDERSTORM WARNING FOR EXTREME SOUTH CENTRAL BERKS
AND NORTHWESTERN CHESTER COUNTIES IS CANCELLED...

STORMS HAVE MOVED OUT OF THE AREA. A SEVERE THUNDERSTORM WATCH 
REMAINS IN EFFECT UNTIL 800 PM EDT FRIDAY EVENING FOR DELAWARE AND 
NORTHEASTERN MARYLAND AND SOUTHERN NEW JERSEY AND SOUTHEAST 
PENNSYLVANIA.

LAT...LON 4002 7597 4003 7595 4011 7595 4014 7590
      4017 7594 4018 7594 4021 7571 3990 7570
      3992 7600 3996 7600
TIME...MOT...LOC 2030Z 270DEG 22KT 4004 7571

$$

JJM/MPD

The office that day

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

IssuedProductOfficeCountiesLasted
May 29, 3:38 PM EDTSevere Thunderstorm WarningPHIChester67 min
May 29, 5:10 PM EDTSevere Thunderstorm WarningPHIDelaware, Philadelphia42 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.