Alert archive / Delaware / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 6, NWS Philadelphia/Mount Holly

May 12, 20184 states

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 12, 2018, 7:16 PM EDT for 4 states. It was in force for 44 min. 2 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, 7:16 PM EDT (23:16 UTC)
Expired
May 12, 2018, 8:00 PM EDT
In force
44 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties New Castle County, DE, Cecil County, MD, Salem County, NJ, Chester County, PA

The radar

The Dover AFB radar (KDOX), 109 km from the middle of the area, began a volume at 23:17 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, 7:25 PM EDTHAIL 0.88Kemblesville, PA
May 12, 7:42 PM EDTHAIL 0.75Newark, DEPEA TO DIME SIZE HAIL REPORTED IN NEWARK.

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

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.3 hours before the alert went out and 150 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, Washington/Dulle, 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, Washington/Dulle, VA at 12:00Z on 2018-05-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 178 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
1390 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
178 m²/s²
0-3 km storm-relative helicity
201 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

753 
WUUS51 KPHI 122316
SVRPHI
DEC003-MDC015-NJC033-PAC029-130000-
/O.NEW.KPHI.SV.W.0006.180512T2316Z-180513T0000Z/

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

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northwestern New Castle County in northern Delaware...
  Northeastern Cecil County in northeastern Maryland...
  West central Salem County in southern New Jersey...
  Southwestern Chester County in southeastern Pennsylvania...

* Until 800 PM EDT.

* At 715 PM EDT, a severe thunderstorm was located over Oxford, or 13
  miles northwest of Newark, moving east at 40 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Newark, Elkton, Calvert, Pennsville, Carneys Point, New Castle,
  Salem, Oxford, Rising Sun, Delaware City, Glen Roy, Zion, Blake,
  Barksdale, Stanton, Glasgow, Bear, Port Penn, Wilmington Manor and
  Pike Creek.

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 northern
Delaware...northeastern Maryland...southern New Jersey...and
southeastern Pennsylvania.

LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
      3980 7605 3981 7603 3966 7541 3947 7548
      3972 7614
TIME...MOT...LOC 2315Z 287DEG 39KT 3977 7598 

HAIL...1.00IN
WIND...60MPH
 
$$
2 follow-up statements
638 
WWUS51 KPHI 122340
SVSPHI

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

DEC003-MDC015-NJC033-PAC029-130000-
/O.CON.KPHI.SV.W.0006.000000T0000Z-180513T0000Z/
New Castle DE-Cecil MD-Salem NJ-Chester PA-
740 PM EDT SAT MAY 12 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 800 PM EDT
FOR NORTHWESTERN NEW CASTLE...NORTHEASTERN CECIL...WEST CENTRAL SALEM
AND SOUTHWESTERN CHESTER COUNTIES...

At 740 PM EDT, a severe thunderstorm was located near Stanton, or
near Newark, moving east at 40 mph.

HAZARD...60 mph wind gusts and half dollar size hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Newark, Elkton, Calvert, Pennsville, Carneys Point, New Castle,
Salem, Oxford, Rising Sun, Delaware City, Glen Roy, Zion, Blake,
Barksdale, Stanton, Glasgow, Bear, Wilmington Manor, Pike Creek and
Fair Hill.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A tornado watch remains in effect for the warned area. Tornadoes can
develop quickly from severe thunderstorms. Although a tornado is not
immediately likely, if one is spotted act quickly and move to a place
of safety inside a sturdy structure, such as a basement or small
interior room.

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 northern
Delaware...northeastern Maryland...southern New Jersey...and
southeastern Pennsylvania.

LAT...LON 3974 7612 3973 7610 3976 7606 3980 7605
      3981 7603 3966 7541 3951 7546 3954 7566
      3972 7614
TIME...MOT...LOC 2340Z 289DEG 36KT 3968 7568 

HAIL...1.25IN
WIND...60MPH
 
$$

JRK
552 
WWUS51 KPHI 122356 RRA
SVSPHI

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

DEC003-MDC015-NJC033-PAC029-130005-
/O.EXP.KPHI.SV.W.0006.000000T0000Z-180513T0000Z/
New Castle DE-Cecil MD-Salem NJ-Chester PA-
756 PM EDT SAT MAY 12 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN NEW CASTLE...
NORTHEASTERN CECIL...WEST CENTRAL SALEM AND SOUTHWESTERN CHESTER
COUNTIES WILL EXPIRE AT 800 PM EDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire. However small hail 
and gusty winds are still possible with additional strong 
thunderstorms moving into the area.

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

LAT...LON 3974 7612 3973 7610 3976 7606 3980 7605
      3981 7603 3966 7541 3951 7546 3954 7566
      3972 7614
TIME...MOT...LOC 2355Z 287DEG 39KT 3963 7548 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
May 12, 7:00 PM EDTSevere Thunderstorm WarningPHINew Castle45 min
May 12, 7:10 PM EDTAreal Flood AdvisoryPHINew Castle2 hr
May 12, 7:25 PM EDTSevere Thunderstorm WarningPHIKent, New Castle50 min
May 12, 7:30 PM EDTSevere Thunderstorm WarningPHINew Castle45 min
May 12, 7:45 PM EDTSevere Thunderstorm WarningPHIKent, New Castle45 min
May 12, 7:57 PM EDTAreal Flood AdvisoryPHIKent, New Castle4 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, 7:37 PM EDTAreal Flood AdvisoryPHIBurlington, Camden, Mercer, Monmouth, Ocean2 hr
May 12, 7:48 PM EDTSpecial Marine WarningPHI57 min
May 12, 7:43 PM EDTSpecial Weather StatementPHICecil32 min
May 12, 6:51 PM EDTSpecial Weather StatementPHIChester39 min

Nearby

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