Alert archive / Delaware / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 191, NWS Philadelphia/Mount Holly

August 9, 2009Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 9, 2009, 7:36 PM EDT for Kent County, Sussex County, Delaware. It was in force for 69 min. 2 reports 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: Aug 9, 2009, 7:36 PM EDT (23:36 UTC)
Expired: Aug 9, 2009, 8:45 PM EDT
In force: 69 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Kent County, DE, Sussex County, DE

The radar

The Dover AFB radar (KDOX), 15 km from the middle of the area, began a volume at 23:35 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

Time	Report	Where	Remark
Aug 9, 7:40 PM EDT	TSTM WND DMG	Harrington, DE	WIRES DOWN.
Aug 9, 8:30 PM EDT	TSTM WND GST 45	Rehoboth Beach, DE

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.

Issued	Product	Office	Lasted
Aug 9, 5:33 PM EDT	Severe Thunderstorm Watch	SPC	4 hr

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 11.6 hours before the alert went out and 90 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: 721 J/kg
Mixed-layer CIN: -46 J/kg
Mixed-layer LCL: 814 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 53 m²/s²
0-3 km storm-relative helicity: 134 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.5

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 092336
SVRPHI
DEC001-005-100045-
/O.NEW.KPHI.SV.W.0191.090809T2336Z-090810T0045Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
736 PM EDT SUN AUG 9 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 845 PM EDT

* AT 734 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 7 MILES NORTHEAST OF BIG STONE BEACH TO 8 MILES NORTH OF
  HARRINGTON...OR ALONG A LINE EXTENDING FROM 14 MILES EAST OF DOVER
  TO 10 MILES SOUTHWEST OF DOVER...AND MOVING SOUTHEAST AT 40 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  ANDREWSVILLE AND HARRINGTON AROUND 745 PM EDT...
  SLAUGHTER BEACH AND MILFORD AROUND 750 PM EDT...
  BRIDGEVILLE AND ELLENDALE AROUND 800 PM EDT...
  SEAFORD AND MILTON AROUND 805 PM EDT...
  LEWES AROUND 810 PM EDT...
  SYCAMORE AROUND 815 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM HAS A HISTORY OF PRODUCING WIND DAMAGE ACROSS
THE NORTHERN HALF OF THE STATE. WIND GUSTS TO 65 MPH WERE
REPORTED IN NEWARK AND WIND GUSTS TO AROUND 50 MPH JUST
OCCURRED IN DOVER. THIS IS A DANGEROUS SITUATION.
SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND STAY AWAY FROM
WINDOWS AND TREES

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
SUNDAY EVENING FOR NORTHERN DELAWARE AND NORTHEAST MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA. A SEVERE THUNDERSTORM WATCH ALSO
REMAINS IN EFFECT UNTIL 1100 PM EDT SUNDAY EVENING FOR SOUTHERN
DELAWARE AND NORTHEASTERN MARYLAND.

&&

LAT...LON 3845 7564 3847 7571 3889 7573 3906 7536
      3898 7529 3893 7530 3889 7525 3883 7521
      3879 7513 3879 7511 3881 7509 3880 7507
      3847 7503 3844 7505
TIME...MOT...LOC 2336Z 328DEG 36KT 3907 7526 3902 7560

$$

TFG

1 follow-up statement

000 
WWUS51 KPHI 100031
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
831 PM EDT SUN AUG 9 2009

DEC001-100039-
/O.CAN.KPHI.SV.W.0191.000000T0000Z-090810T0045Z/
KENT DE-
831 PM EDT SUN AUG 9 2009

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN KENT COUNTY IS
CANCELLED...

THE SEVERE THUNDERSTORM HAS MOVED INTO SUSSEX COUNTY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
SUNDAY EVENING FOR SOUTHERN NEW JERSEY. A SEVERE THUNDERSTORM WATCH
ALSO REMAINS IN EFFECT UNTIL 1100 PM EDT SUNDAY EVENING FOR SOUTHERN
DELAWARE AND NORTHEASTERN MARYLAND.

LAT...LON 3845 7564 3847 7571 3859 7572 3862 7554
      3861 7536 3884 7522 3883 7522 3883 7521
      3879 7513 3879 7511 3881 7509 3880 7507
      3847 7503 3844 7505
TIME...MOT...LOC 0029Z 328DEG 36KT 3874 7513

$$

DEC005-100045-
/O.CON.KPHI.SV.W.0191.000000T0000Z-090810T0045Z/
SUSSEX DE-
831 PM EDT SUN AUG 9 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 845 PM EDT
FOR SOUTHEASTERN SUSSEX COUNTY...

AT 828 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS 
TO 60 MPH.  THIS STORM WAS LOCATED NEAR LEWES...OR 14 MILES
EAST OF GEORGETOWN...MOVING SOUTHEAST AT 40 MPH. A GUST FRONT FROM
THIS STORM WAS MOVING ACROSS SOUTHERN SUSSEX COUNTY.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  DEWEY BEACH AND REHOBOTH BEACH BY 835 PM EDT...
  LONG NECK BY 840 PM EDT...
  BETHANY BEACH...OCEAN VIEW...6 MILES NORTH OF SOUTH BETHANY AND 7
  MILES NORTHEAST OF MILLVILLE BY 845 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU SEE THREATENING WEATHER SEEK SHELTER INSIDE A STURDY 
STRUCTURE AND STAY AWAY FROM WINDOWS AND TREES

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
SUNDAY EVENING FOR SOUTHERN NEW JERSEY. A SEVERE THUNDERSTORM WATCH
ALSO REMAINS IN EFFECT UNTIL 1100 PM EDT SUNDAY EVENING FOR SOUTHERN
DELAWARE AND NORTHEASTERN MARYLAND.

&&

LAT...LON 3845 7564 3847 7571 3859 7572 3862 7554
      3861 7536 3884 7522 3883 7522 3883 7521
      3879 7513 3879 7511 3881 7509 3880 7507
      3847 7503 3844 7505
TIME...MOT...LOC 0029Z 328DEG 36KT 3874 7513

$$

TFG

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 11:57 AM EDT	Flash Flood Watch	PHI	New Castle	11 hr
Aug 9, 1:56 PM EDT	Excessive Heat Warning	PHI	New Castle	30 hr
Aug 9, 1:56 PM EDT	Heat Advisory	PHI	Kent, Sussex	30 hr
Aug 9, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	82 min
Aug 9, 6:03 PM EDT	Areal Flood Advisory	PHI	New Castle	117 min
Aug 9, 6:48 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	72 min

Nearby

Severe Thunderstorm Warnings in Delaware, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.