Alert archive / Delaware / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 19, NWS Philadelphia/Mount Holly

April 21, 2021Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Apr 21, 2021, 2:47 PM EDT for Sussex County, Delaware. It was in force for 16 min. 1 report 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, 2021, 2:47 PM EDT (18:47 UTC)
Expired: Apr 21, 2021, 3:03 PM EDT
In force: 16 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 50 km from the middle of the area, began a volume at 18:49 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

Time	Report	Where	Remark
Apr 21, 2:59 PM EDT	TSTM WND GST 60	3 Nw Fenwick Island, DE	PERSONAL WEATHER STATION KDESELBY13.

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.

Issued	Product	Office	Lasted
Apr 21, 12:28 PM EDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 6.8 hours before the alert went out and 68 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: 12 J/kg
Mixed-layer CIN: -142 J/kg
Mixed-layer LCL: 1437 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 136 m²/s²
0-3 km storm-relative helicity: 126 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

370 
WUUS51 KPHI 211847
SVRPHI
DEC005-211915-
/O.NEW.KPHI.SV.W.0019.210421T1847Z-210421T1915Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
247 PM EDT Wed Apr 21 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southeastern Sussex County in southern Delaware...

* Until 315 PM EDT.

* At 247 PM EDT, severe thunderstorms were located along a line
  extending from near Millville to near Ocean Pines, moving east at
  55 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...
  Millville, Ocean View and South Bethany. 

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 3845 7503 3846 7505 3845 7505 3845 7515
      3856 7516 3860 7501 3845 7500
TIME...MOT...LOC 1847Z 252DEG 49KT 3851 7510 3843 7510 

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

JEO

1 follow-up statement

691 
WWUS51 KPHI 211903
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
303 PM EDT Wed Apr 21 2021

DEC005-211913-
/O.CAN.KPHI.SV.W.0019.000000T0000Z-210421T1915Z/
Sussex DE-
303 PM EDT Wed Apr 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN SUSSEX COUNTY IS
CANCELLED...
    
The storms which prompted the warning have moved out of the area.
Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 600 PM EDT for
southern Delaware.

LAT...LON 3845 7503 3846 7505 3845 7505 3845 7515
      3856 7516 3860 7501 3845 7500
TIME...MOT...LOC 1900Z 252DEG 49KT 3851 7510 3843 7510 

$$

JEO

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 21, 1:10 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	50 min
Apr 21, 1:23 PM EDT	Severe Thunderstorm Warning	PHI	Kent	37 min
Apr 21, 2:09 PM EDT	Special Weather Statement	PHI	Sussex	36 min
Apr 21, 2:18 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	42 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2021 Every severe thunderstorm warning in 2021

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.