Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 170, NWS Philadelphia/Mount Holly

August 2, 2009Chester County, Pennsylvania; Cecil County, Maryland; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 2, 2009, 10:08 AM EDT for Chester County, Pennsylvania; Cecil County, Maryland; New Castle County, Delaware. It was in force for 67 min. 6 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 2, 2009, 10:08 AM EDT (14:08 UTC)
Expired: Aug 2, 2009, 11:15 AM EDT
In force: 67 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties New Castle County, DE, Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 99 km from the middle of the area, began a volume at 14:08 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 2, 10:20 AM EDT	FUNNEL CLOUD	Perryville, MD	NUMEROUS TREES DOWN IN PERRYVILLE WITH FUNNEL CLOUD REPORTED.
Aug 2, 10:20 AM EDT	TSTM WND DMG	Perryville, MD	NUMEROUS TREES DOWN IN PERRYVILLE.
Aug 2, 10:25 AM EDT	TSTM WND DMG	Charlestown, MD	NUMEROUS TREES AND WIRES DOWN IN THE CHARLESTOWN AREA.
Aug 2, 10:40 AM EDT	TSTM WND DMG	Elkton, MD	NUMEROUS TREES DOWN.
Aug 2, 11:05 AM EDT	TSTM WND DMG	Hockessin, DE	TREES AND WIRES DOWN IN HOCKESSIN.
Aug 2, 11:10 AM EDT	TSTM WND DMG	Newark, DE	TREES AND WIRES DOWN IN NEWARK.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 2.1 hours before the alert went out and 139 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: 633 J/kg
Mixed-layer CIN: -76 J/kg
Mixed-layer LCL: 689 m above ground
0-6 km bulk shear: 0 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 0 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 021408
SVRPHI
DEC003-MDC015-PAC029-021515-
/O.NEW.KPHI.SV.W.0170.090802T1408Z-090802T1515Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1008 AM EDT SUN AUG 2 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CECIL COUNTY IN NORTHEAST MARYLAND...
  THIS INCLUDES THE CITY OF ELKTON...
  WESTERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...
  THIS INCLUDES THE CITIES OF...NEWARK...MIDDLETOWN...
  SOUTHWESTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 1115 AM EDT

* AT 1007 AM 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 15
  MILES SOUTH OF OCTORARO...OR 22 MILES NORTHEAST OF BALTIMORE...AND
  MOVING EAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  CHARLESTOWN AROUND 1040 AM EDT...
  NORTH EAST AND HOLLYWOOD BEACH AROUND 1045 AM EDT...
  ELKTON AND BRANTWOOD AROUND 1055 AM EDT...
  BARKSDALE AROUND 1100 AM EDT...
  NEWARK AND GLASGOW AROUND 1105 AM EDT...
  BEAR AND SAINT GEORGES AROUND 1110 AM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. 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.

IF YOU SEE THREATENING WEATHER, PLEASE HEAD INDOORS IMMEDIATELY.

&&

LAT...LON 3973 7615 3978 7608 3988 7569 3946 7558
      3939 7605 3941 7605 3945 7600 3946 7602
      3955 7598 3953 7600 3954 7607 3969 7623
      3972 7624
TIME...MOT...LOC 1408Z 249DEG 26KT 3946 7624

$$
 
TFG

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 2, 2:19 AM EDT	Flash Flood Watch	PHI	Berks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more	13 hr
Aug 2, 3:29 AM EDT	Areal Flood Advisory	PHI	Berks	3 hr
Aug 2, 5:54 AM EDT	Areal Flood Advisory	PHI	Chester	3 hr
Aug 2, 7:34 AM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	3 hr
Aug 2, 7:51 AM EDT	Areal Flood Warning	PHI	Chester	4 hr
Aug 2, 9:04 AM EDT	Areal Flood Warning	PHI	Montgomery, Philadelphia	4 hr
Aug 2, 9:06 AM EDT	Flash Flood Warning	PHI	Berks, Carbon, Chester, Lehigh, Monroe, Northampton	4 hr
Aug 2, 10:08 AM EDT	Flash Flood Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	9 hr
Aug 2, 10:24 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery	66 min
Aug 2, 10:53 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	67 min
Aug 2, 11:14 AM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Montgomery, Northampton	61 min
Aug 2, 11:25 AM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	65 min
Aug 2, 11:48 AM EDT	Severe Thunderstorm Warning	PHI	Bucks	57 min
Aug 2, 11:51 AM EDT	Tornado Warning	PHI	Bucks	24 min
Aug 2, 12:33 PM EDT	River Flood Warning	PHI	Bucks	28 hr
Aug 2, 1:25 PM EDT	Areal Flood Warning	PHI	Montgomery, Philadelphia	6 hr
Aug 2, 4:06 PM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh, Monroe, Northampton	4 hr
Aug 2, 4:21 PM EDT	River Flood Warning	PHI	Chester	56 min
Aug 2, 4:22 PM EDT	Flash Flood Warning	PHI	Berks	2 hr
Aug 2, 6:15 PM EDT	Areal Flood Warning	PHI	Montgomery, Philadelphia	4 hr
Aug 2, 6:25 PM EDT	Areal Flood Warning	PHI	Philadelphia	4 hr
Aug 2, 10:32 AM EDT	Tornado Warning	PHI	Cecil	28 min
Aug 2, 10:39 AM EDT	Severe Thunderstorm Warning	PHI	Cecil, Kent, Queen Anne's	96 min
Aug 2, 12:10 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Talbot	65 min
Aug 2, 12:13 PM EDT	Areal Flood Advisory	PHI	Caroline, Kent, Queen Anne's, Talbot	3 hr
Aug 2, 12:53 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	67 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2009 Severe Thunderstorm Warnings in Maryland, 2009 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.