Alert archive / Maryland / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 66, NWS Philadelphia/Mount Holly

June 21, 2017Cumberland County, New Jersey; Kent County, New Castle County, Delaware; 4 counties in Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 21, 2017, 6:57 PM EDT for Cumberland County, New Jersey; Kent County, New Castle County, Delaware; 4 counties in Maryland. 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 21, 2017, 6:57 PM EDT (22:57 UTC)
Expired
Jun 21, 2017, 7:45 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 Kent County, DE, New Castle County, DE, Caroline County, MD, Cecil County, MD, Kent County, MD, Queen Anne's County, MD, Cumberland County, NJ

The radar

The Dover AFB radar (KDOX), 59 km from the middle of the area, began a volume at 22:58 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.0 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 2017-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 31 joules per kilogram.LCLLFCEL10008507005003002001001 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 2017-06-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -27 square meters per square second.1939587897Sfc1 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
31 J/kg
Mixed-layer CIN
-95 J/kg
Mixed-layer LCL
1812 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
-27 m²/s²
0-3 km storm-relative helicity
56 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

681 
WUUS51 KPHI 212257
SVRPHI
DEC001-003-MDC011-015-029-035-NJC011-212345-
/O.NEW.KPHI.SV.W.0066.170621T2257Z-170621T2345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
657 PM EDT WED JUN 21 2017

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southwestern New Castle County in northern Delaware...
  Northern 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...
  Southwestern Cumberland County in southern New Jersey...

* Until 745 PM EDT

* At 656 PM EDT, severe thunderstorms were located along a line
  extending from near Hope Creek to near Kennedyville to near Millers
  Island, moving southeast at 35 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

  IMPACT...Expect damage to trees and power lines. 

* Locations impacted include...
  Dover, Middletown, Smyrna, Chestertown, Camden, Clayton, Cheswold,
  Rock Hall, Greenwich, Church Hill, Cecilton, Millington,
  Sudlersville, Betterton, Bowers, Woodside, Hartly, Old Town,
  Bohemias Mills and Hazlettville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 3926 7622 3929 7617 3932 7618 3942 7600
      3950 7598 3948 7558 3943 7545 3939 7543
      3940 7541 3944 7540 3925 7500 3916 7515
      3937 7547 3927 7537 3904 7537 3908 7623
      3915 7628
TIME...MOT...LOC 2256Z 299DEG 28KT 3944 7556 3931 7607 3922 7637 

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

JRK
2 follow-up statements
458 
WWUS51 KPHI 212319
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
719 PM EDT WED JUN 21 2017

DEC001-003-MDC011-015-029-035-NJC011-212345-
/O.CON.KPHI.SV.W.0066.000000T0000Z-170621T2345Z/
New Castle DE-Kent DE-Queen Anne's MD-Caroline MD-Kent MD-Cecil MD-
Cumberland NJ-
719 PM EDT WED JUN 21 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM EDT
FOR SOUTHWESTERN NEW CASTLE...NORTHERN KENT...NORTHEASTERN QUEEN
ANNE'S...NORTHEASTERN CAROLINE...KENT...SOUTHEASTERN CECIL AND
SOUTHWESTERN CUMBERLAND COUNTIES...

At 719 PM EDT, severe thunderstorms were located along a line
extending from near Greenwich to near Hartly to near Rock Hall,
moving to the east-southeast at 40 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to trees and power lines. 

Locations impacted include...
Dover, Middletown, Smyrna, Chestertown, Camden, Clayton, Cheswold,
Rock Hall, Greenwich, Church Hill, Cecilton, Millington,
Sudlersville, Betterton, Bowers, Woodside, Hartly, Old Town, Bohemias
Mills and Hazlettville.

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 these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3926 7622 3929 7617 3932 7618 3942 7600
      3950 7598 3948 7558 3943 7545 3939 7543
      3940 7541 3944 7540 3925 7500 3916 7515
      3937 7547 3927 7537 3904 7537 3908 7623
      3915 7628
TIME...MOT...LOC 2319Z 291DEG 37KT 3936 7537 3922 7572 3915 7620 

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

JRK
426 
WWUS51 KPHI 212321
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
721 PM EDT WED JUN 21 2017

MDC015-212331-
/O.CAN.KPHI.SV.W.0066.000000T0000Z-170621T2345Z/
Cecil MD-
721 PM EDT WED JUN 21 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN CECIL COUNTY IS
CANCELLED...

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

LAT...LON 3927 7619 3941 7570 3939 7542 3944 7539
      3925 7500 3916 7515 3939 7548 3927 7537
      3904 7537 3906 7585 3915 7575 3924 7575
      3926 7585 3924 7601 3909 7614 3908 7609
      3907 7610 3908 7623 3915 7628
TIME...MOT...LOC 2321Z 291DEG 37KT 3936 7537 3922 7572 3917 7619 

$$

DEC001-003-MDC011-029-035-NJC011-212345-
/O.CON.KPHI.SV.W.0066.000000T0000Z-170621T2345Z/
New Castle DE-Kent DE-Queen Anne's MD-Caroline MD-Kent MD-
Cumberland NJ-
721 PM EDT WED JUN 21 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM EDT
FOR SOUTHWESTERN NEW CASTLE...NORTHERN KENT...NORTHEASTERN QUEEN
ANNE'S...NORTHEASTERN CAROLINE...KENT AND SOUTHWESTERN CUMBERLAND
COUNTIES...

At 721 PM EDT, severe thunderstorms were located along a line
extending from near Greenwich to near Hartly to near Langford, moving
to the east-southeast at 45 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to trees and power lines. 

Locations impacted include...
Dover, Smyrna, Chestertown, Camden, Clayton, Cheswold, Rock Hall,
Greenwich, Millington, Bowers, Woodside, Hartly, Newport, Old Town,
Rising Sun-Lebanon, Woodland Beach, Hazlettville, Morgnec, Delaney
Corner and Dover Base Housing.

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 these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3927 7619 3941 7570 3939 7542 3944 7539
      3925 7500 3916 7515 3939 7548 3927 7537
      3904 7537 3906 7585 3915 7575 3924 7575
      3926 7585 3924 7601 3909 7614 3908 7609
      3907 7610 3908 7623 3915 7628
TIME...MOT...LOC 2321Z 291DEG 37KT 3936 7537 3922 7572 3917 7619 

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

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 21, 4:21 PM EDTSpecial Weather StatementPHIHunterdon39 min
Jun 21, 4:28 PM EDTSevere Thunderstorm WarningPHIBurlington, Camden, Gloucester47 min
Jun 21, 5:03 PM EDTSevere Thunderstorm WarningPHIAtlantic, Burlington, Camden, Gloucester, Ocean42 min
Jun 21, 5:19 PM EDTSevere Thunderstorm WarningPHIBurlington, Monmouth, Ocean41 min
Jun 21, 5:36 PM EDTSpecial Marine WarningPHI84 min
Jun 21, 5:38 PM EDTSevere Thunderstorm WarningPHIAtlantic, Burlington, Camden, Ocean37 min
Jun 21, 5:54 PM EDTSevere Thunderstorm WarningPHIMonmouth, Ocean26 min
Jun 21, 6:03 PM EDTSpecial Marine WarningPHI42 min
Jun 21, 6:25 PM EDTSpecial Marine WarningPHI95 min
Jun 21, 6:27 PM EDTSpecial Weather StatementPHICumberland, Salem33 min
Jun 21, 6:31 PM EDTSevere Thunderstorm WarningPHIAtlantic, Cumberland, Gloucester, Salem44 min
Jun 21, 6:52 PM EDTSpecial Marine WarningPHI53 min
Jun 21, 7:05 PM EDTSpecial Weather StatementPHICape May25 min
Jun 21, 7:11 PM EDTSevere Thunderstorm WarningPHIAtlantic, Cape May, Cumberland64 min
Jun 21, 7:17 PM EDTSpecial Marine WarningPHI88 min
Jun 21, 7:56 PM EDTSpecial Marine WarningPHI94 min
Jun 21, 7:42 PM EDTSevere Thunderstorm WarningPHIKent36 min
Jun 21, 2:51 PM EDTSpecial Weather StatementPHITalbot39 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2017Severe Thunderstorm Warnings in Delaware, 2017Severe Thunderstorm Warnings in New Jersey, 2017Every severe thunderstorm warning in 2017

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.