Alert archive / Delaware / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 264, NWS Philadelphia/Mount Holly

August 19, 2011Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 19, 2011, 2:59 PM EDT for Sussex County, Delaware. It was in force for 61 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 19, 2011, 2:59 PM EDT (18:59 UTC)
Expired: Aug 19, 2011, 4:00 PM EDT
In force: 61 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 24 km from the middle of the area, began a volume at 18:59 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

Wallops Is Stn, VA (KWAL), launched 12:00Z, 7.0 hours before the alert went out and 93 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: 766 J/kg
Mixed-layer CIN: -78 J/kg
Mixed-layer LCL: 1132 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 15 m²/s²
0-3 km storm-relative helicity: 12 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

344 
WUUS51 KPHI 191859
SVRPHI
DEC005-192000-
/O.NEW.KPHI.SV.W.0264.110819T1859Z-110819T2000Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
259 PM EDT FRI AUG 19 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN SUSSEX COUNTY IN SOUTHERN DELAWARE...
  THIS INCLUDES THE CITY OF GEORGETOWN...

* UNTIL 400 PM EDT

* AT 255 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  SLAUGHTER BEACH...OR 17 MILES NORTH OF GEORGETOWN...AND MOVING
  SOUTH AT 15 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  MILTON AND 8 MILES WEST OF LEWES AROUND 330 PM EDT...
  GEORGETOWN AROUND 350 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...CONTINUOUS CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY! LIGHTNING IS ONE OF NATURES GREATEST KILLERS.
REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE
STRUCK BY LIGHTNING.

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...HEAVY RAIN WILL OCCUR
WITH THESE STORMS AND CAUSE LOW-LYING AND POOR DRAINAGE FLOODING.

WIND DAMAGE OR HAIL WILL OCCUR WELL AHEAD OF ANY RAIN OR LIGHTNING.
DO NOT WAIT FOR THE SOUND OF THUNDER BEFORE TAKING COVER. SEEK
SHELTER IMMEDIATELY INSIDE A STURDY STRUCTURE AND STAY AWAY FROM
WINDOWS.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

&&

LAT...LON 3866 7544 3895 7538 3894 7530 3886 7523
      3880 7516 3879 7511 3880 7508 3877 7506
      3866 7506 3866 7508 3868 7509 3868 7512
      3867 7512 3866 7512
TIME...MOT...LOC 1859Z 002DEG 15KT 3890 7529

$$

TFG

2 follow-up statements

675 
WWUS51 KPHI 191929
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
329 PM EDT FRI AUG 19 2011

DEC005-192000-
/O.CON.KPHI.SV.W.0264.000000T0000Z-110819T2000Z/
SUSSEX DE-
329 PM EDT FRI AUG 19 2011

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

AT 325 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
LOCATED NEAR SLAUGHTER BEACH...OR 15 MILES NORTH OF GEORGETOWN...
MOVING SOUTH AT 15 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  MILTON AND 8 MILES WEST OF LEWES BY 350 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

DO NOT WAIT FOR THUNDER BEFORE TAKING COVER. DAMAGING WINDS
ARE EMANATING FROM THE SEVERE THUNDERSTORM IN DELAWARE BAY.
SEEK SHELTER IMMEDIATELY INSIDE A STURDY STRUCTURE AND STAY 
AWAY FROM WINDOWS.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

&&

LAT...LON 3878 7509 3874 7509 3872 7509 3871 7510
      3870 7511 3870 7512 3870 7516 3871 7541
      3895 7538 3894 7530 3886 7523 3880 7516
      3879 7511 3880 7508
TIME...MOT...LOC 1928Z 002DEG 15KT 3888 7529

$$

TFG

360 
WWUS51 KPHI 191957
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
357 PM EDT FRI AUG 19 2011

DEC005-192005-
/O.EXP.KPHI.SV.W.0264.000000T0000Z-110819T2000Z/
SUSSEX DE-
357 PM EDT FRI AUG 19 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN SUSSEX COUNTY
WILL EXPIRE AT 400 PM EDT...

BASED ON DOVER DOPPLER RADAR, WIND GUSTS EMANATING FROM THE DELAWARE BAY 
THUNDERSTORM HAVE DECREASED TO AROUND 35 MPH AND THUS THE WARNING WILL
NOT BE EXTENDED FOR THAT STORM. ITS POSSIBLE ADDITIONAL WARNINGS MAY BE
NEEDED FOR OTHER THUNDERSTORMS LATER THIS AFTERNOON INTO THIS EVENING.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

LAT...LON 3878 7509 3874 7509 3872 7509 3871 7510
      3870 7511 3870 7512 3870 7516 3871 7541
      3895 7538 3894 7530 3886 7523 3880 7516
      3879 7511 3880 7508
TIME...MOT...LOC 1955Z 002DEG 15KT 3877 7530

$$

TFG

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 8:26 PM EDT	Areal Flood Advisory	PHI	New Castle	112 min
Aug 19, 12:50 AM EDT	Special Weather Statement	PHI	New Castle	40 min
Aug 19, 1:14 AM EDT	Areal Flood Advisory	PHI	New Castle	3 hr
Aug 19, 1:44 AM EDT	Special Weather Statement	PHI	New Castle	61 min
Aug 19, 3:06 AM EDT	Areal Flood Advisory	PHI	Kent	114 min
Aug 19, 4:00 AM EDT	Areal Flood Warning	PHI	New Castle	4 hr
Aug 19, 1:20 PM EDT	Special Weather Statement	PHI	Kent, Sussex	85 min
Aug 19, 1:42 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	63 min
Aug 19, 2:09 PM EDT	Areal Flood Advisory	PHI	Sussex	92 min
Aug 19, 2:33 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	7 hr
Aug 19, 2:53 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	52 min
Aug 19, 3:13 PM EDT	Special Weather Statement	PHI	Sussex	92 min
Aug 19, 3:53 PM EDT	Areal Flood Advisory	PHI	Kent, Sussex	5 hr
Aug 19, 4:09 PM EDT	Severe Thunderstorm Warning	PHI	Kent	66 min
Aug 19, 4:23 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	82 min
Aug 19, 4:42 PM EDT	Areal Flood Advisory	PHI	New Castle	4 hr
Aug 19, 4:42 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	63 min
Aug 19, 6:14 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	65 min
Aug 19, 6:34 PM EDT	Areal Flood Advisory	PHI	Sussex	2 hr

Nearby

Severe Thunderstorm Warnings in Delaware, 2011 Every severe thunderstorm warning in 2011

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.