Alert archive / Delaware / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 63, NWS Philadelphia/Mount Holly

August 1, 2018New Castle County, Delaware; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 1, 2018, 10:58 PM EDT for New Castle County, Delaware; Cecil County, Maryland. It was in force for 47 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 1, 2018, 10:58 PM EDT (02:58 UTC)
Expired: Aug 1, 2018, 11:45 PM EDT
In force: 47 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties New Castle County, DE, Cecil County, MD

The radar

The Dover AFB radar (KDOX), 100 km from the middle of the area, began a volume at 02:59 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 00:00Z, 3.0 hours before the alert went out and 142 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 883 J/kg
Mixed-layer CIN: -22 J/kg
Mixed-layer LCL: 1170 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 111 m²/s²
0-3 km storm-relative helicity: 143 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 4.2

Open this sounding in Storm Lab

The text

As transmitted.

626 
WUUS51 KPHI 020258
SVRPHI
DEC003-MDC015-020345-
/O.NEW.KPHI.SV.W.0063.180802T0258Z-180802T0345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
1058 PM EDT WED AUG 1 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northwestern New Castle County in northern Delaware...
  Cecil County in northeastern Maryland...

* Until 1145 PM EDT.

* At 1057 PM EDT, a severe thunderstorm was located near Octoraro, or
  near Havre De Grace, moving east 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...
  Newark, Elkton, Havre De Grace, Calvert, North East, Rising Sun,
  Charlestown, Zion, Blake, Barksdale, Glasgow, Bear, West
  Nottingham, Octoraro, Brantwood, Fair Hill, Glen Westover, Bay
  View, Mount Pleasant and Lombard.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3973 7568 3951 7565 3950 7598 3952 7598
      3955 7602 3955 7609 3959 7611 3963 7615
      3965 7616 3968 7621 3972 7623
TIME...MOT...LOC 0257Z 266DEG 28KT 3961 7615 

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

Fitzsimmons

1 follow-up statement

860 
WWUS51 KPHI 020325
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1125 PM EDT WED AUG 1 2018

DEC003-MDC015-020345-
/O.CON.KPHI.SV.W.0063.000000T0000Z-180802T0345Z/
New Castle DE-Cecil MD-
1125 PM EDT WED AUG 1 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1145 PM EDT
FOR NORTHWESTERN NEW CASTLE AND NORTHEASTERN CECIL COUNTIES...

At 1124 PM EDT, a severe thunderstorm was located over Zion, or 9
miles northwest of Elkton, moving east at 25 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Newark, Elkton, Havre De Grace, Calvert, North East, Rising Sun,
Charlestown, Zion, Blake, Barksdale, Glasgow, Bear, West Nottingham,
Fair Hill, Glen Westover, Bay View, Lombard, Woodlawn, Andora and
Pleasant Hill.

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.

&&

LAT...LON 3959 7611 3972 7612 3972 7611 3973 7568
      3959 7566 3956 7610
TIME...MOT...LOC 0324Z 260DEG 24KT 3968 7596 

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

Fitzsimmons

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 1, 11:35 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	20 min
Aug 2, 5:36 PM EDT	Special Weather Statement	PHI	New Castle	24 min
Aug 2, 5:40 PM EDT	Special Weather Statement	PHI	Kent	35 min
Aug 2, 4:37 PM EDT	Special Weather Statement	PHI	Queen Anne's	23 min
Aug 2, 5:03 PM EDT	Special Weather Statement	PHI	Kent	27 min
Aug 2, 5:34 PM EDT	Special Weather Statement	PHI	Queen Anne's	26 min
Aug 2, 6:07 PM EDT	Special Weather Statement	PHI	Kent, Queen Anne's	38 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2018 Severe Thunderstorm Warnings in Maryland, 2018 Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.