Alert archive / Maryland / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 284, NWS Philadelphia/Mount Holly

August 21, 2011Cecil County, Kent County, Queen Anne's County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 21, 2011, 2:01 PM EDT for Cecil County, Kent County, Queen Anne's County, Maryland. It was in force for 59 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 21, 2011, 2:01 PM EDT (18:01 UTC)
Expired: Aug 21, 2011, 3:00 PM EDT
In force: 59 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Cecil County, MD, Kent County, MD, Queen Anne's County, MD

The radar

The Dover AFB radar (KDOX), 81 km from the middle of the area, began a volume at 18:01 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 21, 12:52 PM EDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.0 hours before the alert went out and 123 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: 1589 J/kg
Mixed-layer CIN: -99 J/kg
Mixed-layer LCL: 969 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 131 m²/s²
0-3 km storm-relative helicity: 125 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 4.9

Open this sounding in Storm Lab

The text

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

128 
WUUS51 KPHI 211801
SVRPHI
MDC015-029-035-211900-
/O.NEW.KPHI.SV.W.0284.110821T1801Z-110821T1900Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
201 PM EDT SUN AUG 21 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN CECIL COUNTY IN NORTHEAST MARYLAND...
  KENT COUNTY IN NORTHEAST MARYLAND...
  NORTHEASTERN QUEEN ANNE'S COUNTY IN NORTHEAST MARYLAND...

* UNTIL 300 PM EDT

* AT 157 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 OVER
  THE BAY OFF NEWTOWN...AND MOVING EAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  NEWTOWN AROUND 210 PM EDT...
  CHESTERTOWN AROUND 220 PM EDT...
  BETTERTON AROUND 225 PM EDT...
  MORGNEC AROUND 230 PM EDT...
  KENNEDYVILLE AROUND 235 PM EDT...
  SASSAFRAS...MASSEY...CECILTON AND WARWICK AROUND 300 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. 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...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.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT SUNDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

&&

LAT...LON 3918 7628 3934 7618 3934 7615 3938 7611
      3938 7607 3944 7600 3946 7602 3953 7599
      3955 7604 3959 7579 3923 7576 3914 7628
TIME...MOT...LOC 1800Z 256DEG 18KT 3928 7622

$$

IOVINO

1 follow-up statement

581 
WWUS51 KPHI 211833
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
233 PM EDT SUN AUG 21 2011

MDC015-029-035-211900-
/O.CON.KPHI.SV.W.0284.000000T0000Z-110821T1900Z/
CECIL MD-KENT MD-QUEEN ANNE'S MD-
233 PM EDT SUN AUG 21 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 300 PM EDT
FOR NORTHEASTERN QUEEN ANNE'S...KENT AND SOUTHEASTERN CECIL
COUNTIES...

AT 230 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 NEWTOWN...MOVING EAST AT 20 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  CHESTERTOWN BY 240 PM EDT...
  BETTERTON AND KINGSTOWN BY 245 PM EDT...
  MORGNEC BY 250 PM EDT...
  KENNEDYVILLE BY 255 PM EDT...
  GALENA...CRUMPTON...CECILTON AND MASSEY BY 300 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. 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...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.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT SUNDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

&&

LAT...LON 3918 7628 3934 7618 3934 7615 3938 7611
      3938 7607 3944 7600 3946 7602 3953 7599
      3955 7604 3959 7579 3923 7576 3914 7628
TIME...MOT...LOC 1833Z 256DEG 18KT 3929 7614

$$

IOVINO

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 3:28 AM EDT	Flash Flood Watch	PHI	Cecil, Kent	17 hr
Aug 21, 8:01 AM EDT	Special Weather Statement	PHI	Cecil, Kent	59 min
Aug 21, 9:08 AM EDT	Special Weather Statement	PHI	Cecil, Kent	52 min
Aug 21, 9:36 AM EDT	Areal Flood Advisory	PHI	Cecil, Kent, Queen Anne's	2 hr
Aug 21, 2:43 PM EDT	Areal Flood Advisory	PHI	Cecil, Kent, Queen Anne's	3 hr
Aug 21, 2:55 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Queen Anne's, Talbot	65 min
Aug 21, 3:11 PM EDT	Areal Flood Advisory	PHI	Kent, Queen Anne's	2 hr
Aug 21, 4:03 PM EDT	Special Weather Statement	PHI	Caroline, Kent, Queen Anne's, Talbot	57 min
Aug 21, 4:45 PM EDT	Flash Flood Warning	PHI	Kent	3 hr
Aug 21, 5:09 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	37 min
Aug 21, 5:20 PM EDT	Areal Flood Advisory	PHI	Caroline, Queen Anne's, Talbot	115 min
Aug 21, 7:17 PM EDT	Areal Flood Advisory	PHI	Caroline	118 min

Nearby

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.