Alert archive / Delaware / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 230, NWS Philadelphia/Mount Holly

September 18, 2012Caroline County, Maryland; Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 18, 2012, 5:57 PM EDT for Caroline County, Maryland; Kent County, Sussex County, Delaware. It was in force for 78 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
Sep 18, 2012, 5:57 PM EDT (21:57 UTC)
Expired
Sep 18, 2012, 7:15 PM EDT
In force
78 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Kent County, DE, Sussex County, DE, Caroline County, MD

The radar

The Dover AFB radar (KDOX), 16 km from the middle of the area, began a volume at 22:00 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

TimeReportWhereRemark
Sep 18, 6:55 PM EDTTSTM WND DMGWoodlawn, MDTREES DOWN WITH POWER OUTAGES ALONG ROUTE 13 NEAR THE DELAWARE STATE LINE

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.

IssuedProductOfficeLasted
Sep 18, 12:10 PM EDTTornado WatchSPC9 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 10.0 hours before the alert went out and 77 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-pSkew-T log-p diagram, Phillips Aaf/Abe, MD at 12:00Z on 2012-09-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 330 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phillips Aaf/Abe, MD at 12:00Z on 2012-09-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 265 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
330 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
519 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
265 m²/s²
0-3 km storm-relative helicity
275 m²/s²
Significant tornado parameter
0.4
Supercell composite
2.3

Open this sounding in Storm Lab

The text

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

980 
WUUS51 KPHI 182157
SVRPHI
DEC001-005-MDC011-182315-
/O.NEW.KPHI.SV.W.0230.120918T2157Z-120918T2315Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
557 PM EDT TUE SEP 18 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 715 PM EDT

* AT 552 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
  EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
  FROM 8 MILES NORTH OF SMYRNA TO 26 MILES SOUTH OF CHOPTANK...AND
  MOVING NORTHEAST AT 40 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  HAZLETTVILLE AND CHESWOLD AROUND 605 PM EDT...
  AGNER AROUND 610 PM EDT...
  SMITHVILLE...WOODLAND BEACH...DOVER SPEEDWAY AND FEDERALSBURG
  AROUND 615 PM EDT...
  ANDREWSVILLE...VIOLA AND DOVER AROUND 620 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. IF A TORNADO
IS SPOTTED... ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY
STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE 
IMMEDIATELY FOR DAMAGING WINDS...HAIL...AND DEADLY CLOUD TO GROUND 
LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...PREFERABLY 
INSIDE A STRONG BUILDING BUT 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 3845 7569 3865 7572 3870 7584 3867 7594
      3870 7600 3878 7597 3881 7590 3885 7593
      3913 7580 3914 7575 3930 7572 3931 7559
      3937 7551 3932 7543 3907 7539 3898 7530
      3892 7530 3880 7517 3880 7508 3844 7505
TIME...MOT...LOC 2157Z 238DEG 34KT 3943 7556 3835 7607

$$

IOVINO
1 follow-up statement
958 
WWUS51 KPHI 182243
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
643 PM EDT TUE SEP 18 2012

MDC011-182252-
/O.CAN.KPHI.SV.W.0230.000000T0000Z-120918T2315Z/
CAROLINE MD-
643 PM EDT TUE SEP 18 2012

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

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 3846 7569 3868 7572 3931 7559 3937 7551
      3932 7543 3907 7539 3898 7530 3892 7530
      3880 7517 3880 7508 3844 7505
TIME...MOT...LOC 2242Z 238DEG 34KT 3965 7509 3858 7561

$$

DEC001-005-182315-
/O.CON.KPHI.SV.W.0230.000000T0000Z-120918T2315Z/
KENT DE-SUSSEX DE-
643 PM EDT TUE SEP 18 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 PM EDT
FOR SUSSEX AND KENT COUNTIES...

AT 637 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING
WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE 
EXTENDING FROM WOODLAND BEACH TO FARMINGTON TO SEAFORD...MOVING 
NORTHEAST AT 40 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  SYCAMORE...BIG STONE BEACH AND ELLENDALE BY 650 PM EDT...
  GUMBORO BY 655 PM EDT...
  SLAUGHTER BEACH BY 700 PM EDT...
  SELBYVILLE...MILLSBORO...FRANKFORD AND DAGSBORO BY 705 PM EDT...
  MILTON BY 710 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. IF A TORNADO
IS SPOTTED... ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY
STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE 
IMMEDIATELY FOR DAMAGING WINDS...HAIL...AND DEADLY CLOUD TO GROUND 
LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...PREFERABLY 
INSIDE A STRONG BUILDING BUT 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 3846 7569 3868 7572 3931 7559 3937 7551
      3932 7543 3907 7539 3898 7530 3892 7530
      3880 7517 3880 7508 3844 7505
TIME...MOT...LOC 2242Z 238DEG 34KT 3965 7509 3858 7561

$$

IOVINO

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 18, 4:13 AM EDTCoastal Flood AdvisoryPHICaroline, Cecil, Kent, Queen Anne's, Talbot21 hr
Sep 18, 3:32 PM EDTSpecial Weather StatementPHICecil, Kent, Queen Anne's, Talbot58 min
Sep 18, 3:51 PM EDTSevere Thunderstorm WarningPHICecil, Kent, Queen Anne's84 min
Sep 18, 4:35 PM EDTAreal Flood AdvisoryPHICecil, Kent55 min
Sep 18, 4:42 PM EDTSevere Thunderstorm WarningPHICaroline, Queen Anne's, Talbot78 min
Sep 17, 8:54 PM EDTRip Current StatementPHISussex23 hr
Sep 18, 4:21 PM EDTSevere Thunderstorm WarningPHINew Castle69 min
Sep 18, 5:12 PM EDTAreal Flood AdvisoryPHINew Castle63 min
Sep 18, 5:23 PM EDTSevere Thunderstorm WarningPHINew Castle52 min
Sep 18, 7:08 PM EDTSevere Thunderstorm WarningPHISussex38 min
Sep 18, 7:16 PM EDTAreal Flood AdvisoryPHISussex59 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2012Severe Thunderstorm Warnings in Maryland, 2012Every severe thunderstorm warning in 2012

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.