Alert archive / Maryland / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 220, NWS Philadelphia/Mount Holly

August 21, 2009Salem County, New Jersey; Cecil County, Kent County, Queen Anne's County, Maryland; Kent County, New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 21, 2009, 4:13 PM EDT for Salem County, New Jersey; Cecil County, Kent County, Queen Anne's County, Maryland; Kent County, New Castle County, Delaware. It was in force for 77 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, 2009, 4:13 PM EDT (20:13 UTC)
Expired: Aug 21, 2009, 5:30 PM EDT
In force: 77 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

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

The radar

The Dover AFB radar (KDOX), 80 km from the middle of the area, began a volume at 20:16 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, 12:36 PM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 8.2 hours before the alert went out and 39 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: 96 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 930 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 43 m²/s²
0-3 km storm-relative helicity: 108 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.6

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 212013
SVRPHI
DEC001-003-MDC015-029-035-NJC033-212130-
/O.NEW.KPHI.SV.W.0220.090821T2013Z-090821T2130Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
413 PM EDT FRI AUG 21 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN KENT COUNTY IN CENTRAL DELAWARE...
  THIS INCLUDES THE CITY OF DOVER...
  CECIL COUNTY IN NORTHEAST MARYLAND...
  THIS INCLUDES THE CITY OF ELKTON...
  NORTHEASTERN KENT COUNTY IN NORTHEAST MARYLAND...
  NORTHEASTERN QUEEN ANNES COUNTY IN NORTHEAST MARYLAND...
  NEW CASTLE COUNTY IN NORTHERN DELAWARE...
  THIS INCLUDES THE CITIES OF...WILMINGTON...NEWARK...MIDDLETOWN...
  EXTREME NORTHWESTERN SALEM COUNTY IN SOUTHERN NEW JERSEY...

* UNTIL 530 PM EDT

* AT 412 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM.  THIS STORM WAS LOCATED NEAR NORTH EAST...OR
  NEAR ELKTON...AND MOVING NORTHEAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  ELKTON AROUND 420 PM EDT...
  BARKSDALE...CHERRY HILL AND GLASGOW AROUND 425 PM EDT...
  NEWARK AROUND 430 PM EDT...
  PIKE CREEK AROUND 440 PM EDT...
  STANTON AROUND 445 PM EDT...
  HOCKESSIN AROUND 450 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT FRIDAY
EVENING FOR NEW JERSEY AND EASTERN PENNSYLVANIA. A SEVERE
THUNDERSTORM WATCH ALSO REMAINS IN EFFECT UNTIL 900 PM EDT FRIDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW
JERSEY.

&&

LAT...LON 3970 7578 3983 7565 3983 7547 3972 7549
      3960 7560 3959 7559 3964 7556 3964 7554
      3949 7556 3950 7558 3948 7555 3946 7558
      3947 7554 3945 7556 3912 7539 3904 7570
      3916 7576 3946 7601 3953 7599 3957 7609
TIME...MOT...LOC 2013Z 219DEG 24KT 3959 7589

$$

NIERENBERG

1 follow-up statement

000 
WWUS51 KPHI 212101
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
501 PM EDT FRI AUG 21 2009

MDC015-029-035-212110-
/O.CAN.KPHI.SV.W.0220.000000T0000Z-090821T2130Z/
CECIL MD-KENT MD-QUEEN ANNES MD-
501 PM EDT FRI AUG 21 2009

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN QUEEN ANNES...
NORTHEASTERN KENT AND CECIL COUNTIES IS CANCELLED...

THE THUNDERSTORMS THAT PROMPTED THE WARNING HAVE MOVED OUT OF THE 
AREA.


A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT FRIDAY
EVENING FOR NEW JERSEY AND EASTERN PENNSYLVANIA. A SEVERE
THUNDERSTORM WATCH ALSO REMAINS IN EFFECT UNTIL 900 PM EDT FRIDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW
JERSEY.

LAT...LON 3916 7574 3941 7577 3950 7578 3961 7576
      3969 7577 3983 7565 3983 7547 3972 7549
      3960 7560 3959 7559 3964 7556 3964 7554
      3949 7556 3950 7558 3948 7555 3946 7558
      3947 7554 3945 7556 3912 7539 3904 7570
TIME...MOT...LOC 2100Z 219DEG 24KT 3983 7564

$$

DEC001-003-NJC033-212130-
/O.CON.KPHI.SV.W.0220.000000T0000Z-090821T2130Z/
KENT DE-SALEM NJ-NEW CASTLE DE-
501 PM EDT FRI AUG 21 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM EDT
FOR NEW CASTLE...EXTREME WEST CENTRAL SALEM AND NORTHERN KENT
COUNTIES...

AT 500 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM.  THIS STORM WAS LOCATED NEAR
ASHLAND...OR 9 MILES NORTHWEST OF WILMINGTON...MOVING NORTHEAST AT 30
MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  TALLEYVILLE BY 505 PM EDT...
  7 MILES NORTHWEST OF ARDEN...7 MILES NORTHWEST OF ARDENTOWN AND 7
  MILES NORTHWEST OF ARDENCROFT BY 510 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT FRIDAY
EVENING FOR NEW JERSEY AND EASTERN PENNSYLVANIA. A SEVERE
THUNDERSTORM WATCH ALSO REMAINS IN EFFECT UNTIL 900 PM EDT FRIDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW
JERSEY.

&&

LAT...LON 3916 7574 3941 7577 3950 7578 3961 7576
      3969 7577 3983 7565 3983 7547 3972 7549
      3960 7560 3959 7559 3964 7556 3964 7554
      3949 7556 3950 7558 3948 7555 3946 7558
      3947 7554 3945 7556 3912 7539 3904 7570
TIME...MOT...LOC 2100Z 219DEG 24KT 3983 7564

$$

NIERENBERG

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 6:11 AM EDT	Coastal Flood Statement	PHI	Atlantic, Cape May, Monmouth, Ocean	9 hr
Aug 21, 2:34 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	63 min
Aug 21, 2:41 PM EDT	Areal Flood Advisory	PHI	Morris, Sussex, Warren	3 hr
Aug 21, 2:47 PM EDT	Flash Flood Watch	PHI	Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 10 more	35 hr
Aug 21, 3:12 PM EDT	High Surf Advisory	PHI	Atlantic, Cape May, Monmouth, Ocean	53 hr
Aug 21, 4:16 PM EDT	Special Marine Warning	PHI		59 min
Aug 21, 3:28 PM EDT	Severe Thunderstorm Warning	PHI	Cecil, Kent, Queen Anne's	62 min
Aug 21, 3:48 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Queen Anne's, Talbot	57 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2009 Severe Thunderstorm Warnings in Delaware, 2009 Severe Thunderstorm Warnings in New Jersey, 2009 Every severe thunderstorm warning in 2009

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.