Alert archive / Maryland / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 290, NWS Philadelphia/Mount Holly

August 21, 20114 counties in Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 21, 2011, 5:09 PM EDT for 4 counties in Maryland. It was in force for 37 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, 5:09 PM EDT (21:09 UTC)
Expired: Aug 21, 2011, 5:46 PM EDT
In force: 37 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Caroline County, MD, Kent County, MD, Queen Anne's County, MD, Talbot County, MD

The radar

The Dover AFB radar (KDOX), 61 km from the middle of the area, began a volume at 21:11 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, 9.2 hours before the alert went out and 110 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.

990 
WUUS51 KPHI 212109
SVRPHI
MDC011-029-035-041-212215-
/O.NEW.KPHI.SV.W.0290.110821T2109Z-110821T2215Z/

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

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN CAROLINE COUNTY IN EASTERN MARYLAND...
  NORTHEASTERN TALBOT COUNTY IN EASTERN MARYLAND...
  SOUTH CENTRAL KENT COUNTY IN NORTHEAST MARYLAND...
  QUEEN ANNE'S COUNTY IN NORTHEAST MARYLAND...
  THIS INCLUDES THE CITY OF CENTERVILLE...

* UNTIL 615 PM EDT

* AT 507 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
  WYE MILLS...OR NEAR CENTERVILLE...AND MOVING EAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  CENTERVILLE AND CENTREVILLE AROUND 515 PM EDT...
  STARR AND CARVILLE AROUND 525 PM EDT...
  HOPE AROUND 535 PM EDT...
  JUMPTOWN AROUND 540 PM EDT...
  OAKLAND AND RIDGELY AROUND 545 PM EDT...
  GREENSBORO AROUND 600 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 3883 7619 3890 7620 3890 7619 3891 7620
      3898 7621 3900 7618 3901 7619 3905 7620
      3916 7619 3919 7576 3884 7573 3881 7620
TIME...MOT...LOC 2109Z 261DEG 15KT 3900 7609

$$

IOVINO

2 follow-up statements

300 
WWUS51 KPHI 212134
SVSPHI

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

MDC029-212144-
/O.CAN.KPHI.SV.W.0290.000000T0000Z-110821T2215Z/
KENT MD-
534 PM EDT SUN AUG 21 2011

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL KENT 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.

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 3916 7606 3917 7604 3919 7576 3884 7573
      3882 7603
TIME...MOT...LOC 2134Z 261DEG 20KT 3903 7587

$$

MDC011-035-041-212215-
/O.CON.KPHI.SV.W.0290.000000T0000Z-110821T2215Z/
CAROLINE MD-QUEEN ANNE'S MD-TALBOT MD-
534 PM EDT SUN AUG 21 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM EDT
FOR NORTHEASTERN TALBOT...EASTERN QUEEN ANNE'S AND NORTHERN CAROLINE
COUNTIES...

AT 532 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 OAKLAND...MOVING EAST AT 25 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  GREENSBORO BY 540 PM EDT...
  GOLDSBORO BY 545 PM EDT...
  HENDERSON AND TEMPLEVILLE BY 550 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.

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 3916 7606 3917 7604 3919 7576 3884 7573
      3882 7603
TIME...MOT...LOC 2134Z 261DEG 20KT 3903 7587

$$

IOVINO

065 
WWUS51 KPHI 212146
SVSPHI

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

MDC011-035-041-212156-
/O.CAN.KPHI.SV.W.0290.000000T0000Z-110821T2215Z/
CAROLINE MD-QUEEN ANNE'S MD-TALBOT MD-
546 PM EDT SUN AUG 21 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN TALBOT...EASTERN
QUEEN ANNE'S AND NORTHERN CAROLINE COUNTIES IS CANCELLED...

THE THUNDERSTORM CONTINUES TO WEAKEN. AS A RESULT...THE SEVERE 
THUNDERSTORM WARNING HAS BEEN 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.

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 3916 7606 3917 7604 3919 7576 3884 7573
      3882 7603
TIME...MOT...LOC 2146Z 261DEG 20KT 3904 7578

$$

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, 2:01 PM EDT	Severe Thunderstorm Warning	PHI	Cecil, Kent, Queen Anne's	59 min
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, 5:20 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.