Alert archive / Delaware / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 38, NWS Philadelphia/Mount Holly

April 28, 2011Sussex County, Delaware; Caroline County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Apr 28, 2011, 5:38 PM EDT for Sussex County, Delaware; Caroline County, Maryland. It was in force for 39 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: Apr 28, 2011, 5:38 PM EDT (21:38 UTC)
Expired: Apr 28, 2011, 6:17 PM EDT
In force: 39 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Sussex County, DE, Caroline County, MD

The radar

The Dover AFB radar (KDOX), 8 km from the middle of the area, began a volume at 21:39 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, 9.6 hours before the alert went out and 92 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: 90 J/kg
Mixed-layer CIN: -342 J/kg
Mixed-layer LCL: 795 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 295 m²/s²
0-3 km storm-relative helicity: 277 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.

606 
WUUS51 KPHI 282138
SVRPHI
DEC005-MDC011-282245-
/O.NEW.KPHI.SV.W.0038.110428T2138Z-110428T2245Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
538 PM EDT THU APR 28 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN CAROLINE COUNTY IN EASTERN MARYLAND...
  NORTHERN SUSSEX COUNTY IN SOUTHERN DELAWARE...
  THIS INCLUDES THE CITY OF GEORGETOWN...

* UNTIL 645 PM EDT

* AT 534 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DESTRUCTIVE WINDS IN
  EXCESS OF 70 MPH.  THIS STORM WAS LOCATED 6 MILES SOUTHWEST OF
  FEDERALSBURG...OR 17 MILES SOUTHEAST OF EASTON...AND MOVING
  NORTHEAST AT 50 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  SEAFORD AND 8 MILES SOUTHEAST OF SMITHVILLE AROUND 545 PM EDT...
  BRIDGEVILLE AROUND 550 PM EDT...
  ELLENDALE AND GEORGETOWN AROUND 600 PM EDT...
  MILTON AROUND 605 PM EDT...
  LEWES AND 8 MILES SOUTHEAST OF SLAUGHTER BEACH AROUND 610 PM EDT...
  CAPE HENLOPEN STATE PARK AROUND 615 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.

&&

LAT...LON 3865 7572 3869 7583 3869 7589 3882 7571
      3884 7551 3889 7547 3895 7532 3881 7518
      3879 7513 3881 7508 3878 7506 3872 7507
      3854 7570
TIME...MOT...LOC 2138Z 247DEG 53KT 3863 7576

$$

NIERENBERG

2 follow-up statements

105 
WWUS51 KPHI 282203
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
603 PM EDT THU APR 28 2011

MDC011-282213-
/O.CAN.KPHI.SV.W.0038.000000T0000Z-110428T2245Z/
CAROLINE MD-
603 PM EDT THU APR 28 2011

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN CAROLINE COUNTY
IS CANCELLED...

THE SEVERE THUNDERSTORM IS IN SUSSEX COUNTY DELAWARE.

LAT...LON 3877 7533 3882 7547 3883 7548 3884 7549
      3885 7548 3887 7547 3889 7547 3895 7532
      3881 7518 3879 7513 3881 7508 3878 7506
      3872 7507
TIME...MOT...LOC 2203Z 247DEG 53KT 3887 7535

$$

DEC005-282245-
/O.CON.KPHI.SV.W.0038.000000T0000Z-110428T2245Z/
SUSSEX DE-
603 PM EDT THU APR 28 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM EDT
FOR NORTHEASTERN SUSSEX COUNTY...

AT 600 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR ELLENDALE...OR 11
MILES NORTH OF GEORGETOWN...MOVING NORTHEAST AT 50 MPH.

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.

&&

LAT...LON 3877 7533 3882 7547 3883 7548 3884 7549
      3885 7548 3887 7547 3889 7547 3895 7532
      3881 7518 3879 7513 3881 7508 3878 7506
      3872 7507
TIME...MOT...LOC 2203Z 247DEG 43KT 3887 7535

$$
 
TFG

865 
WWUS51 KPHI 282217
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
617 PM EDT THU APR 28 2011

DEC005-282227-
/O.CAN.KPHI.SV.W.0038.000000T0000Z-110428T2245Z/
SUSSEX DE-
617 PM EDT THU APR 28 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN SUSSEX COUNTY IS
CANCELLED...

THE THUNDERSTORM THAT PROMPTED THE WARNING HAS MOVED OUT OF THE AREA.

LAT...LON 3877 7533 3882 7547 3883 7548 3884 7549
      3885 7548 3887 7547 3889 7547 3895 7532
      3881 7518 3879 7513 3881 7508 3878 7506
      3872 7507
TIME...MOT...LOC 2217Z 247DEG 43KT 3893 7515

$$

NIERENBERG

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 28, 6:12 AM EDT	Special Weather Statement	PHI	New Castle	63 min
Apr 28, 6:56 AM EDT	Severe Thunderstorm Warning	PHI	New Castle	34 min
Apr 28, 11:32 AM EDT	Special Weather Statement	PHI	Kent	58 min
Apr 28, 11:37 AM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	53 min
Apr 28, 12:34 PM EDT	Special Weather Statement	PHI	Kent	56 min
Apr 28, 12:42 PM EDT	Special Weather Statement	PHI	New Castle	63 min
Apr 28, 1:13 PM EDT	Special Weather Statement	PHI	Sussex	62 min
Apr 28, 5:04 PM EDT	Special Weather Statement	PHI	Kent, Sussex	56 min
Apr 28, 9:55 AM EDT	River Flood Warning	PHI	Cecil, Harford	66 hr

Nearby

Severe Thunderstorm Warnings in Delaware, 2011 Severe Thunderstorm Warnings in Maryland, 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.