Alert archive / Delaware / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 359, NWS Philadelphia/Mount Holly

September 11, 2023Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 11, 2023, 2:59 PM EDT for Sussex County, Delaware. It was in force for 27 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: Sep 11, 2023, 2:59 PM EDT (18:59 UTC)
Expired: Sep 11, 2023, 3:26 PM EDT
In force: 27 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 40 km from the middle of the area, began a volume at 19:03 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, 7.0 hours before the alert went out and 80 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: 989 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 723 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

859 
WUUS51 KPHI 111859
SVRPHI
DEC005-111945-
/O.NEW.KPHI.SV.W.0359.230911T1859Z-230911T1945Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
259 PM EDT Mon Sep 11 2023

The National Weather Service in Mount Holly NJ has issued a

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

* Until 345 PM EDT.

* At 259 PM EDT, a severe thunderstorm was located over Dagsboro, or
  12 miles southeast of Georgetown, moving east at 5 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  South Bethany.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3861 7512 3865 7505 3864 7504 3850 7504
TIME...MOT...LOC 1859Z 252DEG 5KT 3857 7521 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

PO

3 follow-up statements

816 
WUUS51 KPHI 111902 CCA
SVRPHI
DEC005-111945-
/O.COR.KPHI.SV.W.0359.230911T1859Z-230911T1945Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
302 PM EDT Mon Sep 11 2023

The National Weather Service in Mount Holly NJ has issued a

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

* Until 345 PM EDT.

* At 301 PM EDT, a severe thunderstorm was located over Dagsboro, or
  12 miles southeast of Georgetown, moving east at 5 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  South Bethany.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3861 7512 3865 7505 3864 7504 3850 7504
TIME...MOT...LOC 1901Z 252DEG 5KT 3857 7521 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

PO

498 
WWUS51 KPHI 111916
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
316 PM EDT Mon Sep 11 2023

DEC005-111945-
/O.CON.KPHI.SV.W.0359.000000T0000Z-230911T1945Z/
Sussex DE-
316 PM EDT Mon Sep 11 2023

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 PM EDT
FOR SOUTHEASTERN SUSSEX COUNTY...

At 313 PM EDT, a severe thunderstorm was located north of Millville, 
or 14 miles southeast of Georgetown. The storm is close to or 
over Indian River Bay. It is moving east at 15 mph.  

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

This severe thunderstorm will remain over mainly rural areas of 
southeastern Sussex County. A special marine warning is in effect 
for the adjacent water areas too. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3855 7508 3857 7509 3861 7512 3864 7506
      3854 7504
TIME...MOT...LOC 1913Z 253DEG 11KT 3858 7516 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

PO

078 
WWUS51 KPHI 111926
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
326 PM EDT Mon Sep 11 2023

DEC005-111935-
/O.CAN.KPHI.SV.W.0359.000000T0000Z-230911T1945Z/
Sussex DE-
326 PM EDT Mon Sep 11 2023

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN SUSSEX COUNTY IS
CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled. 

LAT...LON 3855 7508 3857 7509 3861 7512 3864 7506
      3854 7504
TIME...MOT...LOC 1923Z 252DEG 5KT 3859 7514 

$$

PO

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 10, 10:00 PM EDT	Areal Flood Advisory	PHI	New Castle	3 hr
Sep 11, 3:25 PM EDT	Areal Flood Advisory	PHI	Sussex	111 min
Sep 11, 4:55 PM EDT	Areal Flood Advisory	PHI	New Castle	80 min
Sep 11, 5:11 PM EDT	Special Weather Statement	PHI	New Castle	34 min
Sep 11, 5:21 PM EDT	Areal Flood Advisory	PHI	New Castle	102 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2023 Every severe thunderstorm warning in 2023

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.