Alert archive / Delaware / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 87, NWS Philadelphia/Mount Holly

June 20, 2009Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 20, 2009, 6:23 PM EDT for Sussex County, Delaware. It was in force for 27 min. 1 report 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: Jun 20, 2009, 6:23 PM EDT (22:23 UTC)
Expired: Jun 20, 2009, 6:50 PM EDT
In force: 27 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 39 km from the middle of the area, began a volume at 22:23 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
Jun 20, 6:30 PM EDT	TSTM WND DMG	15 Ene Gumboro, DE	TREES DOWN IN MILLVILLE.

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
Jun 20, 3:05 PM EDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 10.4 hours before the alert went out and 69 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: 1201 J/kg
Mixed-layer CIN: -62 J/kg
Mixed-layer LCL: 690 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 138 m²/s²
0-3 km storm-relative helicity: 167 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 5.7

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 202223
SVRPHI
DEC005-202315-
/O.NEW.KPHI.SV.W.0087.090620T2223Z-090620T2315Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
623 PM EDT SAT JUN 20 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 715 PM EDT

* AT 621 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  MILLSBORO...OR 10 MILES SOUTH OF GEORGETOWN...AND MOVING SOUTHEAST
  AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  SELBYVILLE AROUND 640 PM EDT...
  9 MILES SOUTHWEST OF BETHANY BEACH AROUND 645 PM EDT...
  FENWICK ISLAND AROUND 655 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. 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.

&&

LAT...LON 3845 7538 3856 7552 3865 7512 3865 7506
      3861 7504 3846 7503 3844 7505
TIME...MOT...LOC 2223Z 311DEG 24KT 3854 7531

$$

KRUZDLO

1 follow-up statement

000 
WWUS51 KPHI 202250
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
650 PM EDT SAT JUN 20 2009

DEC005-202300-
/O.CAN.KPHI.SV.W.0087.000000T0000Z-090620T2315Z/
SUSSEX DE-
650 PM EDT SAT JUN 20 2009

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN SUSSEX COUNTY IS
CANCELLED...

LAT...LON 3845 7538 3856 7552 3865 7512 3865 7506
      3861 7504 3846 7503 3844 7505
TIME...MOT...LOC 2250Z 311DEG 24KT 3842 7514

$$

KRUZDLO

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 4:27 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	53 min
Jun 20, 5:01 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	59 min
Jun 20, 5:46 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	59 min
Jun 20, 6:55 PM EDT	Coastal Flood Advisory	PHI	Kent, New Castle, Sussex	5 hr

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.