Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 39, NWS Philadelphia/Mount Holly

June 18, 2018Bucks County, Montgomery County, Philadelphia County, Pennsylvania; Burlington County, Camden County, New Jersey

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 18, 2018, 8:42 PM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania; Burlington County, Camden County, New Jersey. It was in force for 48 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: Jun 18, 2018, 8:42 PM EDT (00:42 UTC)
Expired: Jun 18, 2018, 9:30 PM EDT
In force: 48 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Burlington County, NJ, Camden County, NJ, Bucks County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 58 km from the middle of the area, began a volume at 00:44 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.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 0.7 hours before the alert went out and 212 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: 17 J/kg
Mixed-layer CIN: -297 J/kg
Mixed-layer LCL: 1213 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 185 m²/s²
0-3 km storm-relative helicity: 273 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.9

Open this sounding in Storm Lab

The text

As transmitted.

683 
WUUS51 KPHI 190042
SVRPHI
NJC005-007-PAC017-091-101-190130-
/O.NEW.KPHI.SV.W.0039.180619T0042Z-180619T0130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
842 PM EDT MON JUN 18 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northwestern Camden County in southern New Jersey...
  Northwestern Burlington County in southern New Jersey...
  Southeastern Montgomery County in southeastern Pennsylvania...
  South central Bucks County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...

* Until 930 PM EDT.

* At 841 PM EDT, a severe thunderstorm was located over Plymouth
  Meeting, or 10 miles northwest of Philadelphia, moving southeast at
  25 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  Philadelphia, Camden, Gloucester City, Bensalem, Norristown,
  Willingboro, Bellmawr, Burlington, Bristol, Riverside,
  Conshohocken, Palmyra, Hatboro, Ambler, Jenkintown, Westville,
  Narberth, Beverly, Rockledge and Brooklawn.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

In addition to damaging winds, frequent cloud to ground lightning is 
occurring with this storm. Move indoors immediately. Remember, if 
you can hear thunder, you are close enough to be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4007 7479 3986 7511 3989 7514 3988 7516
      3988 7517 4007 7537 4024 7519
TIME...MOT...LOC 0041Z 303DEG 23KT 4013 7525 

HAIL...<.75IN
WIND...60MPH
 
$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 18, 8:36 PM EDT	Special Weather Statement	PHI	Philadelphia	24 min
Jun 18, 8:56 PM EDT	Special Weather Statement	PHI	Mercer, Middlesex, Monmouth	64 min
Jun 18, 8:59 PM EDT	Special Marine Warning	PHI		61 min
Jun 18, 9:40 PM EDT	Special Weather Statement	PHI	Burlington, Ocean	50 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2018 Severe Thunderstorm Warnings in New Jersey, 2018 Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.