Alert archive / Delaware / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 42, NWS Philadelphia/Mount Holly

April 21, 2020Kent County, New Castle County, Sussex County, Delaware; Caroline County, Talbot County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Apr 21, 2020, 2:46 PM EDT for Kent County, New Castle County, Sussex County, Delaware; Caroline County, Talbot County, Maryland. It was in force for 74 min. 5 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
Apr 21, 2020, 2:46 PM EDT (18:46 UTC)
Expired
Apr 21, 2020, 4:00 PM EDT
In force
74 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, Sussex County, DE, Caroline County, MD, Talbot County, MD

The radar

The Dover AFB radar (KDOX), 26 km from the middle of the area, began a volume at 18:46 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
Apr 21, 2:50 PM EDTTSTM WND DMG2 W Hazlettville, DEDAMAGED UTILITY POLE FROM STRONG WINDS. TIME ESTIMATED FROM RADAR.
Apr 21, 2:51 PM EDTTSTM WND GST 56Dover Afb (Kdov), DEKDOV MEASURES A 56 MPH WIND GUST.
Apr 21, 3:20 PM EDTTSTM WND GST 563 Ne Milton, DECORRECTS PREVIOUS TSTM WND GST REPORT FROM 3 NE MILTON. DELDOT SITE MEASURES 56 MPH WIND GUST.
Apr 21, 3:20 PM EDTTSTM WND GST 563 Ne Milton, DEDELDOT SITE MEASURES 56 MPH WIND GUST.
Apr 21, 3:30 PM EDTTSTM WND GST 651 Ene Lewes, DE

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
Apr 21, 1:27 PM EDTSevere Thunderstorm WatchSPC3 hr

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 6.8 hours before the alert went out and 92 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 2020-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 13 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, Wallops Is Stn, VA at 12:00Z on 2020-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 138 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
13 J/kg
Mixed-layer CIN
-182 J/kg
Mixed-layer LCL
938 m above ground
0-6 km bulk shear
52 kt
0-1 km storm-relative helicity
138 m²/s²
0-3 km storm-relative helicity
166 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

986 
WUUS51 KPHI 211846
SVRPHI
DEC001-003-005-MDC011-041-212000-
/O.NEW.KPHI.SV.W.0042.200421T1846Z-200421T2000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
246 PM EDT Tue Apr 21 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Sussex County in southern Delaware...
  Southeastern New Castle County in northern Delaware...
  Kent County in central Delaware...
  Southeastern Talbot County in eastern Maryland...
  Caroline County in eastern Maryland...

* Until 400 PM EDT.

* At 246 PM EDT, severe thunderstorms were located along a line
  extending from near Greenwich to near Andrewsville to near
  University Of Maryland Center For Environmental Studies, moving
  east at 40 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Dover, Georgetown, Smyrna, Milford, Seaford, Denton, Millsboro,
  Laurel, Harrington, Camden, Lewes, Federalsburg, Milton,
  Selbyville, Bridgeville, Greensboro, Delmar, Cheswold, Trappe and
  Dagsboro.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3846 7569 3864 7571 3871 7584 3868 7594
      3857 7602 3863 7608 3864 7615 3889 7589
      3943 7552 3912 7503 3845 7501
TIME...MOT...LOC 1846Z 251DEG 35KT 3935 7536 3886 7571 3853 7614 

HAIL...0.75IN
WIND...60MPH
 
$$

Davis
4 follow-up statements
767 
WWUS51 KPHI 211913
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
313 PM EDT Tue Apr 21 2020

DEC003-MDC011-041-211921-
/O.CAN.KPHI.SV.W.0042.000000T0000Z-200421T2000Z/
New Castle DE-Talbot MD-Caroline MD-
313 PM EDT Tue Apr 21 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN NEW CASTLE...
SOUTHEASTERN TALBOT AND CAROLINE COUNTIES IS CANCELLED...

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

A Severe Thunderstorm Watch remains in effect until 500 PM EDT for
central and southern Delaware...and southern New Jersey.

LAT...LON 3846 7569 3869 7571 3896 7549 3928 7529
      3918 7515 3918 7513 3912 7503 3845 7501
      3846 7505 3845 7505
TIME...MOT...LOC 1911Z 251DEG 35KT 3943 7507 3894 7542 3861 7586 

$$

DEC001-005-212000-
/O.CON.KPHI.SV.W.0042.000000T0000Z-200421T2000Z/
Sussex DE-Kent DE-
313 PM EDT Tue Apr 21 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR SUSSEX AND SOUTHEASTERN KENT COUNTIES...

At 311 PM EDT, severe thunderstorms were located along a line
extending from near Millville to Milford to Hurlock, moving east at
40 mph.

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

SOURCE...Radar indicated. A measured wind gust to 56 mph occurred at 
         Dover at 2:45 PM.

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

Locations impacted include...
Georgetown, Milford, Seaford, Millsboro, Laurel, Lewes, Milton,
Selbyville, Bridgeville, Delmar, Dagsboro, Millville, Ellendale,
Bowers, Henlopen Acres, Gumboro, Cape Henlopen State Park, Sycamore,
Big Stone Beach and Long Neck.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3846 7569 3869 7571 3896 7549 3928 7529
      3918 7515 3918 7513 3912 7503 3845 7501
      3846 7505 3845 7505
TIME...MOT...LOC 1911Z 251DEG 35KT 3943 7507 3894 7542 3861 7586 

HAIL...0.75IN
WIND...60MPH
 
$$

Davis
119 
WWUS51 KPHI 211927
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
327 PM EDT Tue Apr 21 2020

DEC001-211934-
/O.CAN.KPHI.SV.W.0042.000000T0000Z-200421T2000Z/
Kent DE-
327 PM EDT Tue Apr 21 2020

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

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

A Severe Thunderstorm Watch remains in effect until 500 PM EDT for
southern Delaware.

LAT...LON 3846 7569 3853 7569 3885 7538 3916 7510
      3912 7503 3845 7501 3846 7504 3845 7505
TIME...MOT...LOC 1924Z 251DEG 35KT 3947 7492 3898 7527 3865 7571 

$$

DEC005-212000-
/O.CON.KPHI.SV.W.0042.000000T0000Z-200421T2000Z/
Sussex DE-
327 PM EDT Tue Apr 21 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR SUSSEX COUNTY...

At 324 PM EDT, severe thunderstorms were located along a line
extending from near Buena to near Big Stone Beach to near
Federalsburg, moving east at 40 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Georgetown, Millsboro, Laurel, Lewes, Milton, Selbyville, Delmar,
Dagsboro, Millville, Ellendale, Henlopen Acres, Gumboro, Cape
Henlopen State Park, Sycamore, Long Neck, Ocean View, Frankford,
South Bethany, Dewey Beach and Bethel.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3846 7569 3853 7569 3885 7538 3916 7510
      3912 7503 3845 7501 3846 7504 3845 7505
TIME...MOT...LOC 1924Z 251DEG 35KT 3947 7492 3898 7527 3865 7571 

HAIL...0.75IN
WIND...60MPH
 
$$

Davis
443 
WWUS51 KPHI 211939
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
339 PM EDT Tue Apr 21 2020

DEC005-212000-
/O.CON.KPHI.SV.W.0042.000000T0000Z-200421T2000Z/
Sussex DE-
339 PM EDT Tue Apr 21 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR SOUTHERN SUSSEX COUNTY...

At 339 PM EDT, severe thunderstorms were located along a line
extending from Weymouth to 8 miles northwest of North Cape May to
near Bridgeville, moving east at 40 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Millsboro, Laurel, Lewes, Selbyville, Delmar, Dagsboro, Millville,
Henlopen Acres, Gumboro, Cape Henlopen State Park, Long Neck, Ocean
View, Frankford, South Bethany and Dewey Beach.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3846 7569 3852 7569 3863 7534 3890 7503
      3845 7501
TIME...MOT...LOC 1939Z 251DEG 35KT 3952 7474 3903 7509 3870 7553 

HAIL...0.75IN
WIND...60MPH
 
$$

Davis
761 
WWUS51 KPHI 211955
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
355 PM EDT Tue Apr 21 2020

DEC005-212004-
/O.EXP.KPHI.SV.W.0042.000000T0000Z-200421T2000Z/
Sussex DE-
355 PM EDT Tue Apr 21 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN SUSSEX COUNTY WILL
EXPIRE AT 400 PM EDT...
    
The storms which prompted the warning have moved out of the area.
Therefore, the warning will be allowed to expire.

LAT...LON 3846 7569 3852 7569 3863 7534 3890 7503
      3845 7501
TIME...MOT...LOC 1954Z 251DEG 35KT 3957 7456 3908 7491 3875 7535 

$$

Davis

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 21, 3:34 AM EDTFreeze WarningPHIKent, New Castle, Sussex28 hr
Apr 21, 1:38 PM EDTSpecial Weather StatementPHINew Castle52 min
Apr 21, 1:49 PM EDTSevere Thunderstorm WarningPHIKent, New Castle56 min
Apr 21, 2:04 PM EDTSevere Thunderstorm WarningPHIKent, New Castle, Sussex56 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2020Severe Thunderstorm Warnings in Maryland, 2020Every severe thunderstorm warning in 2020

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.