Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 220, NWS Philadelphia/Mount Holly

September 18, 2012Bucks County, Lehigh County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 18, 2012, 2:52 PM EDT for Bucks County, Lehigh County, Northampton County, Pennsylvania. It was in force for 17 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: Sep 18, 2012, 2:52 PM EDT (18:52 UTC)
Expired: Sep 18, 2012, 3:09 PM EDT
In force: 17 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Bucks County, PA, Lehigh County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 101 km from the middle of the area, began a volume at 18:54 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.

Issued	Product	Office	Lasted
Sep 18, 12:10 PM EDT	Tornado Watch	SPC	9 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 6.9 hours before the alert went out and 144 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 330 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 519 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 265 m²/s²
0-3 km storm-relative helicity: 275 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.3

Open this sounding in Storm Lab

The text

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

349 
WUUS51 KPHI 181852
SVRPHI
PAC017-077-095-181930-
/O.NEW.KPHI.SV.W.0220.120918T1852Z-120918T1930Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
252 PM EDT TUE SEP 18 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN LEHIGH COUNTY IN EASTERN PENNSYLVANIA...
  SOUTHERN NORTHAMPTON COUNTY IN EASTERN PENNSYLVANIA...
  NORTHWESTERN BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 330 PM EDT

* AT 250 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH.  THIS STORM WAS LOCATED NEAR GERYVILLE...OR 14 MILES
  SOUTH OF ALLENTOWN...AND MOVING NORTH AT 40 MPH.

  THERE IS LITTLE TO NO LIGHTNING OCCURRING WITH THIS CELL.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  PLEASANT VALLEY AROUND 305 PM EDT...
  HELLERTOWN...SPRINGTOWN AND BETHLEHEM AROUND 310 PM EDT...
  BETHLEHEM AND 6 MILES WEST OF RIEGELSVILLE AROUND 315 PM EDT...
  OLD ORCHARD...WILSON...GLENDON AND 7 MILES EAST OF BATH AROUND 320
  PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DOPPLER RADAR HAS INDICATED SOME ROTATION WITHIN THIS STORM. WHILE
NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. IF A TORNADO IS
SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY
STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

THIS STORM MAY CONTAIN LITTLE OR NO LIGHTNING. DO NOT WAIT TO 
HEAR THUNDER BEFORE TAKING COVER. SEEK SHELTER IMMEDIATELY INSIDE A 
STURDY STRUCTURE AND STAY AWAY FROM WINDOWS.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 700 PM EDT TUESDAY EVENING
FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND EASTERN
PENNSYLVANIA.

&&

LAT...LON 4067 7518 4065 7520 4063 7519 4062 7519
      4062 7520 4059 7519 4057 7519 4033 7532
      4043 7550 4075 7540
TIME...MOT...LOC 1851Z 201DEG 35KT 4041 7541

$$

GORSE

1 follow-up statement

966 
WWUS51 KPHI 181909
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
309 PM EDT TUE SEP 18 2012

PAC017-077-095-181919-
/O.CAN.KPHI.SV.W.0220.000000T0000Z-120918T1930Z/
BUCKS PA-LEHIGH PA-NORTHAMPTON PA-
309 PM EDT TUE SEP 18 2012

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL NORTHAMPTON...
SOUTHEASTERN LEHIGH AND NORTHWESTERN BUCKS COUNTIES IS CANCELLED...

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 700 PM EDT TUESDAY EVENING
FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND EASTERN
PENNSYLVANIA.

LAT...LON 4067 7518 4065 7520 4063 7519 4062 7519
      4062 7520 4059 7519 4057 7519 4033 7532
      4043 7550 4075 7540
TIME...MOT...LOC 1909Z 201DEG 35KT 4057 7533

$$

GORSE

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 18, 4:13 AM EDT	Coastal Flood Advisory	PHI	Delaware, Philadelphia	21 hr
Sep 18, 12:58 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	93 min
Sep 18, 12:59 PM EDT	Special Weather Statement	PHI	Berks, Lehigh	46 min
Sep 18, 1:05 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	115 min
Sep 18, 1:32 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	43 min
Sep 18, 2:00 PM EDT	Special Weather Statement	PHI	Chester, Montgomery	60 min
Sep 18, 2:18 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	57 min
Sep 18, 2:23 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Montgomery	30 min
Sep 18, 2:25 PM EDT	Flash Flood Warning	PHI	Carbon, Lehigh, Monroe, Northampton	4 hr
Sep 18, 3:07 PM EDT	Areal Flood Warning	PHI	Berks, Lehigh	8 hr
Sep 18, 3:16 PM EDT	Special Weather Statement	PHI	Monroe	59 min
Sep 18, 3:24 PM EDT	Special Weather Statement	PHI	Berks, Carbon	51 min
Sep 18, 3:52 PM EDT	Special Weather Statement	PHI	Chester	53 min
Sep 18, 4:05 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	55 min
Sep 18, 4:19 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Delaware, Montgomery	56 min
Sep 18, 4:23 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh, Monroe, Northampton	52 min
Sep 18, 4:26 PM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Northampton	3 hr
Sep 18, 4:35 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Lehigh, Montgomery	55 min
Sep 18, 5:01 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Lehigh, Montgomery, Northampton and 1 more	59 min
Sep 18, 5:12 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Delaware, Montgomery	63 min
Sep 18, 5:12 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	78 min
Sep 18, 5:13 PM EDT	Severe Thunderstorm Warning	PHI	Monroe, Northampton	62 min
Sep 18, 6:00 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	60 min
Sep 18, 6:06 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	54 min
Sep 18, 6:19 PM EDT	Areal Flood Warning	PHI	Carbon, Lehigh, Monroe, Northampton	16 hr
Sep 18, 6:54 PM EDT	Areal Flood Advisory	PHI	Bucks	111 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2012 Every severe thunderstorm warning in 2012

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.