Alert archive / Delaware / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 215, NWS Philadelphia/Mount Holly

July 31, 2011Kent County, New Castle County, Delaware; Kent County, Queen Anne's County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 31, 2011, 3:58 PM EDT for Kent County, New Castle County, Delaware; Kent County, Queen Anne's County, Maryland. It was in force for 36 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
Jul 31, 2011, 3:58 PM EDT (19:58 UTC)
Expired
Jul 31, 2011, 4:34 PM EDT
In force
36 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Kent County, DE, New Castle County, DE, Kent County, MD, Queen Anne's County, MD

What was reported inside it

TimeReportWhereRemark
Jul 31, 4:00 PM EDTTSTM WND DMGClayton, DEPOLES DOWN IN CLAYTON... BLOCKED ROADWAY.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 8.0 hours before the alert went out and 148 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, Wallops Is Stn, VA at 12:00Z on 2011-07-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Wallops Is Stn, VA at 12:00Z on 2011-07-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -22 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2108 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
-22 m²/s²
0-3 km storm-relative helicity
22 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

055 
WUUS51 KPHI 311958
SVRPHI
DEC001-003-MDC029-035-312100-
/O.NEW.KPHI.SV.W.0215.110731T1958Z-110731T2100Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
358 PM EDT SUN JUL 31 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHWESTERN KENT COUNTY IN CENTRAL DELAWARE...
  EXTREME EAST CENTRAL KENT COUNTY IN NORTHEAST MARYLAND...
  NORTHEASTERN QUEEN ANNE'S COUNTY IN NORTHEAST MARYLAND...
  EXTREME SOUTHWESTERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...

* UNTIL 500 PM EDT

* AT 352 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH.  THIS STORM WAS LOCATED NEAR DELANEY CORNER...OR 12
  MILES NORTHWEST OF DOVER...AND MOVING EAST AT 5 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  GREEN SPRING AROUND 405 PM EDT...
  CLAYTON AROUND 415 PM EDT...
  CLAYTON AROUND 420 PM EDT...
  SMYRNA AROUND 430 PM EDT...
  CHESWOLD AROUND 500 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...HEAVY RAIN WILL OCCUR
WITH THESE STORMS AND CAUSE LOW-LYING AND POOR DRAINAGE FLOODING.
THE HEAVY RAIN WILL ALSO LOOSEN THE ROOTS OF WEAKER TREES AND KNOCK 
THEM DOWN.

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 3919 7582 3931 7584 3933 7558 3918 7553
TIME...MOT...LOC 1958Z 290DEG 6KT 3925 7570

$$

TFG
2 follow-up statements
632 
WWUS51 KPHI 312015
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
415 PM EDT SUN JUL 31 2011

DEC003-MDC029-035-312024-
/O.CAN.KPHI.SV.W.0215.000000T0000Z-110731T2100Z/
KENT MD-QUEEN ANNE'S MD-NEW CASTLE DE-
415 PM EDT SUN JUL 31 2011

...THE SEVERE THUNDERSTORM WARNING FOR EXTREME SOUTHWESTERN NEW
CASTLE...NORTHEASTERN QUEEN ANNE'S AND EXTREME EAST CENTRAL KENT
COUNTIES IS CANCELLED...

THE SEVERE THUNDERSTORM IS NOW IN KENT COUNTY DELAWARE.

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 3919 7573 3928 7572 3930 7557 3918 7553
TIME...MOT...LOC 2014Z 290DEG 6KT 3924 7567

$$

DEC001-312100-
/O.CON.KPHI.SV.W.0215.000000T0000Z-110731T2100Z/
KENT DE-
415 PM EDT SUN JUL 31 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 500 PM EDT
FOR NORTHWESTERN KENT COUNTY...

AT 409 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 KENTON...OR 10 MILES 
NORTHWEST OF DOVER...MOVING EAST AT 5 MPH. FLASH FLOODING IS LIKELY
ALSO OCCURRING WITH THIS STORM.

OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
CLAYTON...SMYRNA AND CHESWOLD

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.

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 3919 7573 3928 7572 3930 7557 3918 7553
TIME...MOT...LOC 2014Z 290DEG 6KT 3924 7567

$$

TFG
247 
WWUS51 KPHI 312034
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
434 PM EDT SUN JUL 31 2011

DEC001-312044-
/O.CAN.KPHI.SV.W.0215.000000T0000Z-110731T2100Z/
KENT DE-
434 PM EDT SUN JUL 31 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL KENT COUNTY IS
CANCELLED...

THE THUNDERSTORM HAS WEAKENED BELOW SEVERE LIMITS. HEAVY RAIN THOUGH
CONTINUES TO FALL AND A FLASH FLOOD WARNING REMAINS IN EFFECT FOR 
NORTHERN KENT COUNTY.

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 3919 7573 3928 7572 3930 7557 3918 7553
TIME...MOT...LOC 2034Z 290DEG 6KT 3923 7563

$$
 
TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 2:09 PM EDTSpecial Weather StatementPHIKent66 min
Jul 31, 2:35 PM EDTAreal Flood AdvisoryPHIKent115 min
Jul 31, 2:45 PM EDTSpecial Weather StatementPHIKent90 min
Jul 31, 3:33 PM EDTFlash Flood WarningPHIKent, New Castle2 hr
Jul 31, 4:36 PM EDTSpecial Weather StatementPHIKent84 min
Jul 31, 4:56 PM EDTSpecial Weather StatementPHISussex64 min
Jul 31, 12:30 PM EDTSpecial Weather StatementPHICaroline60 min
Jul 31, 1:23 PM EDTSpecial Weather StatementPHICaroline82 min
Jul 31, 2:39 PM EDTSpecial Weather StatementPHITalbot96 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2011Severe Thunderstorm Warnings in Maryland, 2011Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive.