Alert archive / Delaware / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 17, NWS Philadelphia/Mount Holly

April 21, 2009Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Apr 21, 2009, 8:13 PM EDT for Kent County, Sussex County, Delaware. It was in force for 47 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
Apr 21, 2009, 8:13 PM EDT (00:13 UTC)
Expired
Apr 21, 2009, 9:00 PM EDT
In force
47 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), 10 km from the middle of the area, began a volume at 00:14 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 nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 00:00Z, 0.2 hours before the alert went out and 104 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-pSkew-T log-p diagram, Wallops Is Stn, VA at 00:00Z on 2009-04-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 205 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Wallops Is Stn, VA at 00:00Z on 2009-04-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 60 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
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
205 J/kg
Mixed-layer CIN
-64 J/kg
Mixed-layer LCL
1104 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
60 m²/s²
0-3 km storm-relative helicity
102 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.8

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 220013
SVRPHI
DEC001-005-220100-
/O.NEW.KPHI.SV.W.0017.090422T0013Z-090422T0100Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
813 PM EDT TUE APR 21 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 900 PM EDT

* AT 812 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 6 MILES NORTHWEST OF SANDTOWN TO 6 MILES WEST OF SEAFORD...OR
  ALONG A LINE EXTENDING FROM 13 MILES EAST OF CENTERVILLE TO 18
  MILES WEST OF GEORGETOWN...AND MOVING NORTHEAST AT 45 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  LAUREL...SANDTOWN AND SEAFORD BY 820 PM EDT...
  HARTLY...SYCAMORE...HAZLETTVILLE AND ANDREWSVILLE BY 825 PM EDT...
  WOODSIDE...VIOLA AND HARRINGTON BY 830 PM EDT...

LAT...LON 3847 7570 3917 7576 3931 7544 3920 7538
      3916 7540 3907 7539 3903 7533 3898 7529
      3893 7530 3880 7517 3868 7510 3868 7512
      3865 7511 3864 7508 3857 7504
TIME...MOT...LOC 0013Z 238DEG 38KT 3907 7581 3865 7572

$$

AMC

Nearby

Severe Thunderstorm Warnings in Delaware, 2009Every 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.