Alert archive / Maryland / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 7, NWS Philadelphia/Mount Holly

May 12, 20184 counties in Maryland; Kent County, New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 12, 2018, 7:25 PM EDT for 4 counties in Maryland; Kent County, New Castle County, Delaware. It was in force for 50 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, 7:25 PM EDT (23:25 UTC)
Expired
May 12, 2018, 8:15 PM EDT
In force
50 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Kent County, DE, New Castle County, DE, Caroline County, MD, Cecil County, MD, Kent County, MD, Queen Anne's County, MD

The radar

The Dover AFB radar (KDOX), 72 km from the middle of the area, began a volume at 23:28 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, 8:12 PM EDTHAIL 12 Ese Lambson, MDPHOTO OF QUARTER SIZED HAIL SOUTH OF GALENA. LOCATION AND TIME APPROXIMATED BASED ON RADAR.
May 12, 8:22 PM EDTHAIL 1.75Butlertown, MDGOLF BALL SIZED HAIL REPORTED FOR SEVERAL MINUTES NORTH OF CHESTERTOWN. TIME 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.4 hours before the alert went out and 124 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.

275 
WUUS51 KPHI 122325
SVRPHI
DEC001-003-MDC011-015-029-035-130015-
/O.NEW.KPHI.SV.W.0007.180512T2325Z-180513T0015Z/

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

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southwestern New Castle County in northern Delaware...
  Northwestern Kent County in central Delaware...
  Northeastern Queen Anne's County in northeastern Maryland...
  Northeastern Caroline County in eastern Maryland...
  Kent County in northeastern Maryland...
  Southeastern Cecil County in northeastern Maryland...

* Until 815 PM EDT.

* At 724 PM EDT, a severe thunderstorm was located over Newtown, or
  11 miles south of Aberdeen Proving Ground, 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...
  Smyrna, Chestertown, Clayton, Church Hill, Cecilton, Millington,
  Sudlersville, Betterton, Hartly, Warwick, Newtown, Morgnec, Delaney
  Corner, Crumpton, Sassafras, Green Spring, Langford, Massey,
  Kennedyville and Townsend.

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 central and
northern Delaware...and eastern and northeastern Maryland.

LAT...LON 3928 7620 3929 7617 3932 7618 3934 7616
      3933 7614 3937 7611 3937 7606 3943 7599
      3941 7560 3928 7559 3908 7566 3908 7577
      3917 7618 3920 7625 3922 7625
TIME...MOT...LOC 2324Z 283DEG 36KT 3931 7620 

HAIL...1.00IN
WIND...60MPH
 
$$

JRK
2 follow-up statements
358 
WWUS51 KPHI 122356
SVSPHI

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

DEC001-003-MDC011-015-029-035-130015-
/O.CON.KPHI.SV.W.0007.000000T0000Z-180513T0015Z/
New Castle DE-Kent DE-Queen Anne's MD-Caroline MD-Kent MD-Cecil MD-
756 PM EDT SAT MAY 12 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM EDT
FOR SOUTHWESTERN NEW CASTLE...NORTHWESTERN KENT...NORTHEASTERN QUEEN
ANNE'S...NORTHEASTERN CAROLINE...KENT AND SOUTH CENTRAL CECIL
COUNTIES...

At 755 PM EDT, a severe thunderstorm was located over Morgnec, or 14
miles south of Aberdeen Proving Ground, moving east at 30 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...
Smyrna, Chestertown, Clayton, Church Hill, Millington, Sudlersville,
Betterton, Hartly, Green Spring, Newtown, Morgnec, Delaney Corner,
Massey, Crumpton, Kennedyville, Galena, Kenton, Marydel, Templeville
and Barclay.

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.

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

&&

A tornado watch remains in effect until 100 AM EDT for central and
northern Delaware...and eastern and northeastern Maryland.

LAT...LON 3938 7605 3934 7568 3931 7559 3928 7559
      3908 7566 3908 7577 3909 7583 3924 7623
      3928 7620 3929 7617 3932 7618 3934 7616
      3933 7614 3937 7611 3937 7606
TIME...MOT...LOC 2355Z 280DEG 26KT 3927 7604 

HAIL...1.00IN
WIND...60MPH
 
$$

JRK
473 
WWUS51 KPHI 130004
SVSPHI

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

DEC001-003-MDC011-015-029-035-130015-
/O.CON.KPHI.SV.W.0007.000000T0000Z-180513T0015Z/
New Castle DE-Kent DE-Queen Anne's MD-Caroline MD-Kent MD-Cecil MD-
804 PM EDT SAT MAY 12 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM EDT
FOR SOUTHWESTERN NEW CASTLE...NORTHWESTERN KENT...NORTHEASTERN QUEEN
ANNE'S...NORTHEASTERN CAROLINE...KENT AND SOUTH CENTRAL CECIL
COUNTIES...

At 803 PM EDT, a severe thunderstorm was located over Crumpton, or 16
miles northeast of Centerville, moving east at 40 mph.

HAZARD...Golf ball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Wind damage 
         to roofs, siding, trees, and power lines is possible.

Locations impacted include...
Smyrna, Chestertown, Clayton, Church Hill, Millington, Sudlersville,
Betterton, Hartly, Green Spring, Newtown, Morgnec, Delaney Corner,
Massey, Crumpton, Kennedyville, Galena, Kenton, Marydel, Templeville
and Barclay.

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.

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

&&

A tornado watch remains in effect until 100 AM EDT for central and
northern Delaware...and eastern and northeastern Maryland.

LAT...LON 3938 7605 3934 7568 3931 7559 3928 7559
      3908 7566 3908 7577 3909 7583 3924 7623
      3928 7620 3929 7617 3932 7618 3934 7616
      3933 7614 3937 7611 3937 7606
TIME...MOT...LOC 0003Z 283DEG 36KT 3925 7593 

HAIL...1.75IN
WIND...60MPH
 
$$

JRK

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, 7:43 PM EDTSpecial Weather StatementPHICecil32 min
May 12, 7:45 PM EDTSevere Thunderstorm WarningPHICecil45 min
May 12, 7:57 PM EDTAreal Flood AdvisoryPHICaroline, Cecil, Kent, Queen Anne's4 hr
May 12, 7:00 PM EDTSevere Thunderstorm WarningPHINew Castle45 min
May 12, 7:10 PM EDTAreal Flood AdvisoryPHINew Castle2 hr
May 12, 7:30 PM EDTSevere Thunderstorm WarningPHINew Castle45 min

Nearby

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