Alert archive / New Jersey / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 9, NWS Philadelphia/Mount Holly

May 12, 20184 states

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 12, 2018, 7:45 PM EDT for 4 states. It was in force for 45 min. 4 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 12, 2018, 7:45 PM EDT (23:45 UTC)
Expired
May 12, 2018, 8:30 PM EDT
In force
45 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Tornado
Possible
Hail
1.0 in
Wind
60.0 mph

Counties Kent County, DE, New Castle County, DE, Cecil County, MD, Atlantic County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 77 km from the middle of the area, began a volume at 23:46 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 12, 7:46 PM EDTHAIL 0.75Elsmere, DEHAIL UP TO PENNY SIZE IN ELSMERE. TIME APPROXIMATED FROM RADAR.
May 12, 7:50 PM EDTHAIL 1Chesapeake City, MDPHOTO OF QUARTER SIZED HAIL AT CANAL VIEW ESTATES IN CHESAPEAKE CITY. TIME APPROXIMATED FROM RADAR.
May 12, 7:58 PM EDTHAIL 0.751 Ne Cleland Heights, DE
May 12, 8:10 PM EDTHAIL 0.75Alloway, NJTIME APPROXIMATED FROM RADAR.

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 12, 4:58 PM EDTTornado WatchSPC5 hr

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 11.8 hours before the alert went out and 192 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, Wallops Is Stn, VA at 12:00Z on 2018-05-12Temperature 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, Wallops Is Stn, VA at 12:00Z on 2018-05-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 283 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
1692 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
283 m²/s²
0-3 km storm-relative helicity
314 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

758 
WUUS51 KPHI 122345
SVRPHI
DEC001-003-MDC015-NJC001-007-011-015-033-PAC045-130030-
/O.NEW.KPHI.SV.W.0009.180512T2345Z-180513T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
745 PM EDT SAT MAY 12 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Central New Castle County in northern Delaware...
  North central Kent County in central Delaware...
  East central Cecil County in northeastern Maryland...
  Northwestern Atlantic County in southern New Jersey...
  Cumberland County in southern New Jersey...
  Salem County in southern New Jersey...
  Camden County in southern New Jersey...
  Gloucester County in southern New Jersey...
  Southeastern Delaware County in southeastern Pennsylvania...

* Until 830 PM EDT.

* At 744 PM EDT, severe thunderstorms were located along a line
  extending from Broomall to Wilmington to Brantwood, moving
  southeast at 40 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Trained weather spotters.

  IMPACT...Minor damage to vehicles is possible. Wind damage to 
           roofs, siding, trees, and power lines is possible.

* Locations impacted include...
  Wilmington, Vineland, Millville, Bridgeton, Middletown, Elkton,
  Cumberland, Chester, Deptford, West Deptford, Glassboro,
  Lindenwold, Hammonton, Pennsville, Bellmawr, Woodbury, Pitman,
  Clayton, Carneys Point and Berlin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to large hail and 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.

&&

A tornado watch remains in effect until 100 AM EDT for central and
northern Delaware...northeastern Maryland...southern New Jersey...and
southeastern Pennsylvania.

LAT...LON 3953 7591 3973 7560 3997 7543 3992 7525
      3987 7526 3987 7521 3989 7515 3981 7491
      3978 7489 3979 7485 3978 7479 3967 7466
      3942 7482 3917 7518 3939 7548 3939 7549
      3925 7537
TIME...MOT...LOC 2344Z 297DEG 38KT 3999 7537 3972 7555 3956 7579 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$
2 follow-up statements
948 
WWUS51 KPHI 130019
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
819 PM EDT SAT MAY 12 2018

MDC015-NJC007-PAC045-130028-
/O.CAN.KPHI.SV.W.0009.000000T0000Z-180513T0030Z/
Cecil MD-Camden NJ-Delaware PA-
819 PM EDT SAT MAY 12 2018

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL CECIL...CAMDEN
AND SOUTHEASTERN DELAWARE COUNTIES IS CANCELLED...

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

A tornado watch remains in effect until 100 AM EDT for central and
northern Delaware...and southern New Jersey.

LAT...LON 3942 7569 3958 7541 3975 7524 3954 7474
      3942 7482 3931 7499 3930 7498 3930 7499
      3917 7518 3939 7548 3939 7549 3925 7537
TIME...MOT...LOC 0018Z 297DEG 38KT 3984 7499 3957 7517 3941 7541 

$$

DEC001-003-NJC001-011-015-033-130030-
/O.CON.KPHI.SV.W.0009.000000T0000Z-180513T0030Z/
New Castle DE-Kent DE-Atlantic NJ-Cumberland NJ-Salem NJ-
Gloucester NJ-
819 PM EDT SAT MAY 12 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 830 PM EDT
FOR SOUTH CENTRAL NEW CASTLE...NORTH CENTRAL KENT...WEST CENTRAL
ATLANTIC...CUMBERLAND...SALEM AND SOUTHEASTERN GLOUCESTER COUNTIES...

At 818 PM EDT, severe thunderstorms were located along a line
extending from Echelon to Elmer to Newport Meadows, moving southeast
at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Trained weather spotters.

IMPACT...Minor damage to vehicles is possible. Wind damage to roofs, 
         siding, trees, and power lines is possible.

Locations impacted include...
Vineland, Millville, Bridgeton, Cumberland, Glassboro, Clayton,
Buena, Laurel Lake, Woodstown, Alloway, Weymouth, Quinton, Newfield,
Elmer, Greenwich, Shiloh, Newport, Franklinville, Woodland Beach and
Hancocks Bridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to large hail and 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.

&&

A tornado watch remains in effect until 100 AM EDT for central and
northern Delaware...and southern New Jersey.

LAT...LON 3942 7569 3958 7541 3975 7524 3954 7474
      3942 7482 3931 7499 3930 7498 3930 7499
      3917 7518 3939 7548 3939 7549 3925 7537
TIME...MOT...LOC 0018Z 297DEG 38KT 3984 7499 3957 7517 3941 7541 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$
083 
WWUS51 KPHI 130027
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
827 PM EDT SAT MAY 12 2018

DEC001-003-NJC001-011-015-033-130037-
/O.EXP.KPHI.SV.W.0009.000000T0000Z-180513T0030Z/
New Castle DE-Kent DE-Atlantic NJ-Cumberland NJ-Salem NJ-
Gloucester NJ-
827 PM EDT SAT MAY 12 2018

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL NEW CASTLE...
NORTH CENTRAL KENT...WEST CENTRAL ATLANTIC...CUMBERLAND...SALEM AND
SOUTHEASTERN GLOUCESTER COUNTIES WILL EXPIRE AT 830 PM EDT...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However small hail
and gusty winds are still possible with these thunderstorms.

A tornado watch remains in effect until 100 AM EDT for central and
northern Delaware...and southern New Jersey.

LAT...LON 3942 7569 3958 7541 3975 7524 3954 7474
      3942 7482 3931 7499 3930 7498 3930 7499
      3917 7518 3939 7548 3939 7549 3925 7537
TIME...MOT...LOC 0027Z 297DEG 38KT 3981 7490 3954 7508 3938 7532 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
May 12, 7:16 PM EDTSevere Thunderstorm WarningPHICecil44 min
May 12, 7:25 PM EDTSevere Thunderstorm WarningPHICaroline, Cecil, Kent, Queen Anne's50 min
May 12, 7:43 PM EDTSpecial Weather StatementPHICecil32 min
May 12, 7:57 PM EDTAreal Flood AdvisoryPHICaroline, Cecil, Kent, Queen Anne's4 hr
May 12, 6:26 AM EDTSpecial Weather StatementPHIAtlantic49 min
May 12, 7:02 AM EDTSpecial Marine WarningPHI58 min
May 12, 6:53 PM EDTSpecial Weather StatementPHIMercer52 min
May 12, 7:00 PM EDTSevere Thunderstorm WarningPHIGloucester, Salem45 min
May 12, 7:30 PM EDTSevere Thunderstorm WarningPHIGloucester, Salem45 min
May 12, 7:37 PM EDTAreal Flood AdvisoryPHIBurlington, Camden, Mercer, Monmouth, Ocean2 hr
May 12, 7:48 PM EDTSpecial Marine WarningPHI57 min
May 12, 7:10 PM EDTAreal Flood AdvisoryPHINew Castle2 hr
May 12, 6:51 PM EDTSpecial Weather StatementPHIChester39 min

Nearby

Severe Thunderstorm Warnings in New Jersey, 2018Severe Thunderstorm Warnings in Delaware, 2018Severe Thunderstorm Warnings in Maryland, 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.