Alert archive / Delaware / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 237, NWS Philadelphia/Mount Holly

August 12, 2020Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 12, 2020, 3:15 PM EDT for Kent County, Sussex County, Delaware. It was in force for 45 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
Aug 12, 2020, 3:15 PM EDT (19:15 UTC)
Expired
Aug 12, 2020, 4:00 PM EDT
In force
45 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Kent County, DE, Sussex County, DE

The radar

The Dover AFB radar (KDOX), 15 km from the middle of the area, began a volume at 19:15 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

Wallops Is Stn, VA (KWAL), launched 12:00Z, 7.3 hours before the alert went out and 97 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 2020-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1590 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 2020-08-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 3 square meters per square second.1939Sfc1 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
1590 J/kg
Mixed-layer CIN
-21 J/kg
Mixed-layer LCL
729 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
17 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

290 
WUUS51 KPHI 121915
SVRPHI
DEC001-005-122000-
/O.NEW.KPHI.SV.W.0237.200812T1915Z-200812T2000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
315 PM EDT Wed Aug 12 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northwestern Sussex County in southern Delaware...
  Southern Kent County in central Delaware...

* Until 400 PM EDT.

* At 315 PM EDT, a severe thunderstorm was located over Andrewsville,
  or 15 miles northwest of Georgetown, moving north at 30 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Milford, Seaford, Harrington, Bridgeville, Ellendale, Andrewsville,
  Blades, Greenwood, Houston and Farmington.

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.

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 3864 7571 3885 7573 3900 7573 3899 7528
      3863 7548
TIME...MOT...LOC 1915Z 193DEG 26KT 3885 7559 

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

Gorse
1 follow-up statement
491 
WWUS51 KPHI 121931 RRA
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
331 PM EDT Wed Aug 12 2020

DEC001-005-122000-
/O.CON.KPHI.SV.W.0237.000000T0000Z-200812T2000Z/
Sussex DE-Kent DE-
331 PM EDT Wed Aug 12 2020

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

At 331 PM EDT, a severe thunderstorm was located over Harrington, or
15 miles south of Dover, moving north at 20 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Milford, Harrington, Bridgeville, Ellendale, Andrewsville, Greenwood,
Houston and Farmington.

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.

Frequent cloud to ground lightning is occurring with this storm. Move
indoors immediately. Lightning is one of nature's leading killers.
Remember, if you can hear thunder, you are close enough to be struck
by lightning.

&&

LAT...LON 3886 7573 3900 7573 3899 7528 3878 7540
      3872 7571
TIME...MOT...LOC 1931Z 200DEG 16KT 3894 7555 

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

Gorse

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 12, 12:43 PM EDTAreal Flood AdvisoryPHINew Castle3 hr
Aug 12, 12:55 PM EDTAreal Flood AdvisoryPHIKent, New Castle3 hr
Aug 12, 12:55 PM EDTSpecial Weather StatementPHIKent35 min
Aug 12, 1:06 PM EDTFlash Flood WarningPHIKent, New Castle3 hr
Aug 12, 1:37 PM EDTAreal Flood AdvisoryPHINew Castle3 hr
Aug 12, 1:54 PM EDTSevere Thunderstorm WarningPHINew Castle51 min
Aug 12, 2:38 PM EDTSevere Thunderstorm WarningPHIKent52 min
Aug 12, 2:40 PM EDTFlash Flood WarningPHINew Castle3 hr
Aug 12, 3:06 PM EDTAreal Flood AdvisoryPHIKent, Sussex3 hr
Aug 12, 3:20 PM EDTSevere Thunderstorm WarningPHINew Castle29 min
Aug 12, 3:31 PM EDTFlash Flood WarningPHIKent3 hr
Aug 12, 3:46 PM EDTFlash Flood WarningPHIKent, Sussex3 hr
Aug 12, 4:00 PM EDTSpecial Weather StatementPHIKent30 min

Nearby

Severe Thunderstorm Warnings in Delaware, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.