Alert archive / Delaware / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 171, NWS Philadelphia/Mount Holly

July 8, 2011Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 8, 2011, 7:49 PM EDT for Sussex County, Delaware. It was in force for 56 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: Jul 8, 2011, 7:49 PM EDT (23:49 UTC)
Expired: Jul 8, 2011, 8:45 PM EDT
In force: 56 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 35 km from the middle of the area, began a volume at 23:51 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
Jul 8, 1:51 PM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 11.8 hours before the alert went out and 83 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: 489 J/kg
Mixed-layer CIN: -43 J/kg
Mixed-layer LCL: 890 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

267 
WUUS51 KPHI 082349
SVRPHI
DEC005-090045-
/O.NEW.KPHI.SV.W.0171.110708T2349Z-110709T0045Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
749 PM EDT FRI JUL 8 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EASTERN SUSSEX COUNTY IN SOUTHERN DELAWARE...

* UNTIL 845 PM EDT

* AT 746 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
  LEWES...OR 10 MILES EAST OF GEORGETOWN...AND MOVING EAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  LEWES AROUND 800 PM EDT...
  CAPE HENLOPEN STATE PARK AND REHOBOTH BEACH AROUND 810 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 FRIDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW
JERSEY.

&&

LAT...LON 3845 7526 3885 7530 3883 7520 3879 7513
      3879 7511 3881 7509 3880 7507 3865 7505
      3863 7506 3860 7504 3859 7505 3847 7503
      3845 7503 3844 7505
TIME...MOT...LOC 2349Z 255DEG 16KT 3874 7520

$$

NIERENBERG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 8, 3:58 AM EDT	Flash Flood Watch	PHI	Kent, New Castle, Sussex	19 hr
Jul 8, 2:12 PM EDT	Special Weather Statement	PHI	New Castle	93 min
Jul 8, 2:25 PM EDT	Areal Flood Advisory	PHI	New Castle	7 hr
Jul 8, 4:17 PM EDT	Special Weather Statement	PHI	Kent, Sussex	88 min
Jul 8, 5:44 PM EDT	Flash Flood Warning	PHI	New Castle	3 hr
Jul 8, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	Kent	82 min
Jul 8, 6:02 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle, Sussex	4 hr
Jul 8, 6:23 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	82 min
Jul 8, 7:46 PM EDT	Special Weather Statement	PHI	Sussex	59 min

Nearby

Severe Thunderstorm Warnings in Delaware, 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.