Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 17, NWS Philadelphia/Mount Holly

May 15, 20186 counties in Pennsylvania; 6 counties in New Jersey

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 15, 2018, 4:41 PM EDT for 6 counties in Pennsylvania; 6 counties in New Jersey. It was in force for 64 min. 32 reports 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 15, 2018, 4:41 PM EDT (20:41 UTC)
Expired
May 15, 2018, 5:45 PM EDT
In force
64 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
70.0 mph

Counties Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Somerset County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 75 km from the middle of the area, began a volume at 20:44 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 15, 4:41 PM EDTTSTM WND DMGLake Parsippany, NJDOWNED TREE ON INTERSTATE 287 NEAR EXIT 40. LANE CLOSURES IN PLACE. TIME APPROXIMATED FROM RADAR.
May 15, 4:41 PM EDTTSTM WND DMGTabor, NJDOWNED TREE ON STATE HIGHWAY 53 NEAR FRONT STREET IN DENVILLE TWP. ALL LANES CLOSED. TIME APPROXIMATED FROM RADAR.
May 15, 4:42 PM EDTTSTM WND DMGBoonton, NJTREES DOWN THROUGHOUT BOONTON. SEVERAL ROADS CLOSED. TIME APPROXIMATED FROM RADAR.
May 15, 4:42 PM EDTTSTM WND DMGLittleton, NJDOWNED TREE ON U.S. HIGHWAY 202 NEAR STATE HIGHWAY 10 IN MORRIS PLAINS. ALL LANES CLOSED AND DETOURED. TIME APPROXIMATED FROM RADAR.
May 15, 4:45 PM EDTTSTM WND DMGLake Hiawatha, NJLARGE TREE DOWN CRUSHING 2 CARS
May 15, 4:45 PM EDTTSTM WND GST 68Lower Macungie Twp, PAWIND GUST OF 68 MPH MEASURED WITH HAND HELD ANEMOMETER...HOWEVER THE DEVICE HAD NOT BEEN CALIBRATED RECENTLY. TREE DAMAGE ALSO REPORTED
May 15, 4:46 PM EDTTSTM WND DMGPohatcong Twp, NJNUMEROUS TREES, POWER LINES, AND UTILITY POLES DOWN THROUGHOUT POHATCONG TWP. SEVERAL ROAD CLOSURES IN PLACE.
May 15, 4:46 PM EDTTSTM WND GST 551 S Ruscomb Manor Twp, PACWOP STATION REPORTS WIND GUST OF 55 MPH
May 15, 4:49 PM EDTTSTM WND DMGMalapardis, NJDOWNED TREE ON INTERSTATE 287 NEAR EXIT 39. LANE CLOSURES IN PLACE. TIME APPROXIMATED FROM RADAR.
May 15, 4:51 PM EDTTSTM WND DMGHampton, NJMULTIPLE TREES AND POWER LINES DOWN. TIME ESTIMATED FROM RADAR.
May 15, 4:51 PM EDTTSTM WND DMGPine Brook, NJNUMEROUS TREES DOWN IN PINE BROOK. SEVERAL ROADS ARE CLOSED. TIME APPROXIMATED FROM RADAR.
May 15, 4:55 PM EDTTSTM WND DMGWyomissing, PA6 INCH DIAMTER TREE SNAPPED AT THE BASE. TIME ESTIMATED FROM RADAR
May 15, 4:57 PM EDTTSTM WND DMGWest Reading, PATREE DOWN ON A HOUSE. NO INJURIES REPORTED. TIME ESTIMATED FROM RADAR.
May 15, 4:59 PM EDTTSTM WND DMGCollege Heights, PADOWNED TREES ON SKYLINE DRIVE NEAR MCKNIGHT GAP ROAD. TIME ESTIMATED FROM RADAR.
May 15, 4:59 PM EDTHAIL 1Bally, PA
May 15, 5:00 PM EDTTSTM WND GST 60West Lawn, PALARGE TREE DOWN IN PICTURE.
May 15, 5:00 PM EDTTSTM WND GST 67Lebanon, NJ
May 15, 5:02 PM EDTTSTM WND DMGPennside, PADOWNED TREE DAMAGED A HOUSE. TIME ESTIMATED FROM RADAR.
May 15, 5:04 PM EDTTSTM WND DMGOley Twp, PANUMEROUS TREES DOWN IN OLEY TOWNSHIP, WITH SEVERAL ROADS CLOSED. TIME ESTIMATED FROM RADAR.
May 15, 5:07 PM EDTTSTM WND DMGWest Rockhill Twp, PAFALLEN TREES DAMAGED A HOUSE IN WEST ROCKHILL TWP. TIME ESTIMATED FROM RADAR.
May 15, 5:10 PM EDTTSTM WND DMGDouglassville, PATREES AND POWERLINES DOWN.
May 15, 5:13 PM EDTTSTM WND GST 64Port Reading, NJ
May 15, 5:14 PM EDTTSTM WND DMG1 N Snowdenville, PAREPORT OF TREES AND POWER LINES DOWN NEAR THE INTERSECTION OF SAYLORS MILL RD AND EBELHARE RD
May 15, 5:16 PM EDTTSTM WND GST 81Pottstown, PAMEASURED BY HOME ROOFTOP WEATHER STATION. TREE DAMAGE AND ALSO SOME WINDOW DAMAGE TO A HOME. PROBABLE MICROBURST.
May 15, 5:17 PM EDTHAIL 1Pottstown, PAQUARTER SIZE HAIL LASTED FOR 8 MINUTES.
May 15, 5:19 PM EDTHAIL 1Pottstown, PAREPORT RELAYED VIA BROADCAST MEDIA THAT QUARTER SIZE HAIL FELL IN POTTSTOWN FOR AT LEAST 8 MINUTES. TIME ESTIAMTE FROM RADAR
May 15, 5:20 PM EDTHAIL 0.75Stowe, PA
May 15, 5:25 PM EDTTSTM WND DMGPhoenixville, PATREE DOWN ON BRIDGE STREET. TIME ESTIMATED FROM RADAR
May 15, 5:32 PM EDTTSTM WND DMGGraterford, PALARGE LIMB AND POWER LINES DOWN IN NEIGHBORHOOD. *EVENT TIME CORRECTED*
May 15, 5:48 PM EDTTSTM WND DMG1 Wnw Rushland, PALARGE TREES UPROOTED NEAR SWAMP ROAD AND RUSHLAND ROAD IN JAMISON. TIME ESTIMATED FROM RADAR.
May 15, 5:54 PM EDTTSTM WND DMGPlymouth Valley, PALARGE TREE DOWN, DAMAGING A RESIDENTIAL PROPERTY, ON MILL CREEK ROAD. TIME ESTIMATED BY RADAR.
May 15, 5:55 PM EDTTSTM WND DMGPlymouth Meadows, PASEVERAL TREES DOWN ON MALVERN ROAD.

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 15, 1:46 PM EDTSevere Thunderstorm WatchSPC9 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 8.7 hours before the alert went out and 142 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, Brookhaven, NY at 12:00Z on 2018-05-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Brookhaven, NY at 12:00Z on 2018-05-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 107 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
909 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
107 m²/s²
0-3 km storm-relative helicity
153 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

060 
WUUS51 KPHI 152041
SVRPHI
NJC019-021-023-027-035-041-PAC011-017-029-077-091-095-152145-
/O.NEW.KPHI.SV.W.0017.180515T2041Z-180515T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
441 PM EDT TUE MAY 15 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Morris County in northern New Jersey...
  Hunterdon County in northwestern New Jersey...
  Southwestern Warren County in northwestern New Jersey...
  Northwestern Mercer County in central New Jersey...
  Somerset County in northern New Jersey...
  Northern Middlesex County in northern New Jersey...
  Southeastern Berks County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  Southeastern Lehigh County in eastern Pennsylvania...
  Bucks County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  Southeastern Northampton County in eastern Pennsylvania...

* Until 545 PM EDT.

* At 441 PM EDT, severe thunderstorms were located along a line 
  extending from near Hawthorne to Spring Ridge, moving east at 55 
  mph.

  HAZARD...70 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Minor damage to vehicles is possible. Expect considerable 
           tree damage. Wind damage is also likely to mobile homes, 
           roofs, and outbuildings.

* Locations impacted include...
  Allentown, Reading, New Brunswick, Perth Amboy, Morristown,
  Somerville, Somerset, Edison, Bethlehem, East Brunswick,
  Bridgewater, South Brunswick, Sayreville, North Brunswick, Ewing,
  Norristown, Carteret, Pottstown, Dover and Phoenixville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4056 7421 4055 7425 4050 7426 4050 7428
      4046 7426 4013 7527 4003 7572 4032 7614
      4100 7430 4097 7428 4090 7427 4091 7433
      4083 7433 4076 7438 4075 7436 4067 7446
      4065 7440 4060 7446 4060 7421
TIME...MOT...LOC 2041Z 284DEG 42KT 4100 7418 4034 7598 

HAIL...1.00IN
WIND...70MPH
 
$$

po
2 follow-up statements
805 
WWUS51 KPHI 152110
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
510 PM EDT TUE MAY 15 2018

NJC019-021-023-027-035-041-PAC011-017-029-077-091-095-152145-
/O.CON.KPHI.SV.W.0017.000000T0000Z-180515T2145Z/
Morris NJ-Hunterdon NJ-Warren NJ-Mercer NJ-Somerset NJ-Middlesex NJ-
Berks PA-Montgomery PA-Lehigh PA-Bucks PA-Chester PA-Northampton PA-
510 PM EDT TUE MAY 15 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM EDT
FOR MORRIS...HUNTERDON...SOUTHWESTERN WARREN...NORTHWESTERN MERCER...
SOMERSET...NORTHERN MIDDLESEX...SOUTHEASTERN BERKS...MONTGOMERY...
SOUTHEASTERN LEHIGH...BUCKS...NORTHEASTERN CHESTER AND SOUTHEASTERN
NORTHAMPTON COUNTIES...

At 510 PM EDT, severe thunderstorms were located along a line
extending from New York to near Glenmoore, moving southeast at 25
mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to vehicles is possible. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

Locations impacted include...
Allentown, Reading, New Brunswick, Perth Amboy, Morristown,
Somerville, Somerset, Edison, Bethlehem, East Brunswick, Bridgewater,
South Brunswick, Sayreville, North Brunswick, Ewing, Norristown,
Carteret, Pottstown, Dover and Phoenixville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Wind damage with these storms will occur before any rain or
lightning. Do not wait for the sound of thunder before taking cover.
SEEK SHELTER IMMEDIATELY inside a sturdy structure and stay away from
windows.

&&

LAT...LON 4056 7421 4055 7425 4050 7426 4050 7428
      4046 7426 4013 7527 4003 7572 4032 7614
      4100 7430 4097 7428 4090 7427 4091 7433
      4083 7433 4076 7438 4075 7436 4067 7446
      4065 7440 4060 7446 4060 7421
TIME...MOT...LOC 2110Z 322DEG 23KT 4078 7396 4012 7575 

HAIL...1.00IN
WIND...70MPH
 
$$

SFJ
975 
WWUS51 KPHI 152127
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
527 PM EDT TUE MAY 15 2018

NJC041-PAC077-095-152136-
/O.CAN.KPHI.SV.W.0017.000000T0000Z-180515T2145Z/
Warren NJ-Lehigh PA-Northampton PA-
527 PM EDT TUE MAY 15 2018

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

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A severe thunderstorm watch remains in effect until 1100 PM EDT for
central, northern and northwestern New Jersey...and eastern and
southeastern Pennsylvania.

LAT...LON 4056 7421 4055 7425 4050 7426 4050 7428
      4046 7426 4013 7527 4003 7572 4025 7604
      4075 7436 4067 7446 4065 7440 4060 7446
      4060 7421
TIME...MOT...LOC 2126Z 284DEG 42KT 4074 7374 4008 7554 

$$

NJC019-021-023-027-035-PAC011-017-029-091-152145-
/O.CON.KPHI.SV.W.0017.000000T0000Z-180515T2145Z/
Morris NJ-Hunterdon NJ-Mercer NJ-Somerset NJ-Middlesex NJ-Berks PA-
Montgomery PA-Bucks PA-Chester PA-
527 PM EDT TUE MAY 15 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM EDT
FOR SOUTHEASTERN MORRIS...SOUTHEASTERN HUNTERDON...NORTHWESTERN
MERCER...SOMERSET...NORTHERN MIDDLESEX...SOUTHEASTERN BERKS...
MONTGOMERY...BUCKS AND NORTHEASTERN CHESTER COUNTIES...

At 526 PM EDT, severe thunderstorms were located along a line
extending from near Little Neck to near Paoli, moving east at 50 mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to vehicles is possible. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

Locations impacted include...
New Brunswick, Perth Amboy, Somerville, Somerset, Edison, East
Brunswick, Bridgewater, South Brunswick, Sayreville, North Brunswick,
Ewing, Norristown, Carteret, Pottstown, Phoenixville, Lansdale, West
Norriton, Middlesex, East Norriton and Princeton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Wind damage with these storms will occur before any rain or
lightning. Do not wait for the sound of thunder before taking cover.
SEEK SHELTER IMMEDIATELY inside a sturdy structure and stay away from
windows.

&&

LAT...LON 4056 7421 4055 7425 4050 7426 4050 7428
      4046 7426 4013 7527 4003 7572 4025 7604
      4075 7436 4067 7446 4065 7440 4060 7446
      4060 7421
TIME...MOT...LOC 2126Z 284DEG 42KT 4074 7374 4008 7554 

HAIL...1.00IN
WIND...70MPH
 
$$

SFJ

The office that day

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

IssuedProductOfficeCountiesLasted
May 15, 3:40 AM EDTFlash Flood WatchPHIBerks, Bucks, Chester, Delaware, Lehigh, Montgomery and 1 more21 hr
May 15, 2:49 PM EDTSpecial Weather StatementPHIBerks, Carbon, Lehigh, Monroe, Northampton56 min
May 15, 3:20 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe55 min
May 15, 3:46 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh, Northampton74 min
May 15, 4:12 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe33 min
May 15, 4:24 PM EDTSpecial Weather StatementPHIBerks51 min
May 15, 4:26 PM EDTTornado WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton19 min
May 15, 5:12 PM EDTSevere Thunderstorm WarningPHIChester63 min
May 15, 5:14 PM EDTAreal Flood AdvisoryPHIBerks, Chester, Montgomery2 hr
May 15, 5:22 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia38 min
May 15, 5:31 PM EDTAreal Flood AdvisoryPHIBucks, Lehigh, Montgomery3 hr
May 15, 5:35 PM EDTAreal Flood AdvisoryPHIBucks, Chester, Delaware, Montgomery, Philadelphia4 hr
May 15, 5:38 PM EDTSevere Thunderstorm WarningPHIDelaware, Philadelphia67 min
May 15, 5:53 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia52 min
May 15, 6:10 PM EDTAreal Flood AdvisoryPHIPhiladelphia4 hr
May 15, 6:15 PM EDTSevere Thunderstorm WarningPHIChester60 min
May 15, 6:35 PM EDTSevere Thunderstorm WarningPHIChester40 min
May 15, 6:58 PM EDTAreal Flood AdvisoryPHIChester4 hr
May 15, 4:49 PM EDTSpecial Marine WarningPHI86 min
May 15, 6:02 PM EDTSpecial Marine WarningPHI88 min
May 15, 6:12 PM EDTSpecial Marine WarningPHI63 min
May 15, 6:17 PM EDTSpecial Weather StatementPHIBurlington, Camden, Cumberland, Gloucester, Ocean43 min
May 15, 6:46 PM EDTSpecial Weather StatementPHIAtlantic, Cumberland, Ocean, Salem74 min
May 15, 7:14 PM EDTSpecial Marine WarningPHI91 min
May 15, 7:18 PM EDTSevere Thunderstorm WarningPHISalem57 min
May 15, 7:30 PM EDTSpecial Marine WarningPHI90 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2018Severe Thunderstorm Warnings in New Jersey, 2018Every severe thunderstorm warning in 2018

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.