Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2010

Severe Thunderstorm Warning 21, NWS Philadelphia/Mount Holly

May 14, 2010New Castle County, Delaware; Chester County, Delaware County, Pennsylvania; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 14, 2010, 6:35 PM EDT for New Castle County, Delaware; Chester County, Delaware County, Pennsylvania; Cecil County, Maryland. It was in force for 55 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: May 14, 2010, 6:35 PM EDT (22:35 UTC)
Expired: May 14, 2010, 7:30 PM EDT
In force: 55 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

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

The radar

The Dover AFB radar (KDOX), 111 km from the middle of the area, began a volume at 22:35 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
May 14, 6:55 PM EDT	TSTM WND DMG	1 Ese Blake, MD	TREES DOWN ACROSS THE NORTHERN PART OF THE COUNTY.
May 14, 7:14 PM EDT	HAIL 0.75	Newark, DE	A COUPLE OF REPORTS OF PENNY SIZE HAIL IN NEWARK.
May 14, 7:15 PM EDT	HAIL 0.75	Newark, DE	PENNY SIZE HAIL IN NEWARK.
May 14, 7:17 PM EDT	HAIL 1	Bear, DE	QUARTER SIZE HAIL IN BEAR.
May 14, 7:20 PM EDT	HAIL 0.75	Bear, DE
May 14, 7:35 PM EDT	HAIL 0.88	Delaware City, 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
May 14, 3:43 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 10.6 hours before the alert went out and 48 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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 557 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 160 m²/s²
0-3 km storm-relative helicity: 187 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

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

386 
WUUS51 KPHI 142235
SVRPHI
DEC003-MDC015-PAC029-045-142330-
/O.NEW.KPHI.SV.W.0021.100514T2235Z-100514T2330Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
635 PM EDT FRI MAY 14 2010

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 730 PM EDT

* AT 629 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
  A CLUSTER OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE 
  HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE 
  LOCATED 16 MILES NORTHWEST OF ROCK SPRINGS...OR 9 MILES SOUTH OF 
  LANCASTER...AND MOVING SOUTHEAST AT 40 MPH.

* THESE SEVERE THUNDERSTORMS WILL BE NEAR...
  MOUNT VERNON...HOMEVILLE AND GLEN ROY AROUND 655 PM EDT...
  OXFORD AND COCHRANVILLE AROUND 700 PM EDT...
  WEST GROVE AND KEMBLESVILLE AROUND 710 PM EDT...
  LADENBERG AND GLEN WESTOVER AROUND 715 PM EDT...
  NORTH STAR AROUND 720 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
FRIDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY
AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3972 7618 3976 7609 3987 7601 3997 7600
      4013 7592 3998 7546 3996 7547 3993 7543
      3987 7542 3967 7553 3962 7560 3960 7560
      3960 7557 3956 7560
TIME...MOT...LOC 2234Z 288DEG 34KT 3989 7626

$$

HAYES

1 follow-up statement

964 
WWUS51 KPHI 142257
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
657 PM EDT FRI MAY 14 2010

DEC003-MDC015-PAC029-045-142330-
/O.CON.KPHI.SV.W.0021.000000T0000Z-100514T2330Z/
CECIL MD-DELAWARE PA-CHESTER PA-NEW CASTLE DE-
657 PM EDT FRI MAY 14 2010

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM EDT
FOR NORTHERN NEW CASTLE...CHESTER...WESTERN DELAWARE AND NORTHERN
CECIL COUNTIES...

AT 654 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE A CLUSTER OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING 
QUARTER SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS 
STORM WAS LOCATED NEAR MOUNT VERNON...OR 18 MILES NORTHWEST OF 
NEWARK...MOVING EAST AT 40 MPH.

THESE SEVERE THUNDERSTORMS WILL BE NEAR...
  KEMBLESVILLE AND WEST GROVE BY 710 PM EDT...
  LADENBERG...AVONDALE...GLEN WESTOVER AND TOUGHKENAMON BY 715 PM
  EDT...
  NORTH STAR...PIKE CREEK AND HOCKESSIN BY 720 PM EDT...
  STANTON BY 725 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
FRIDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY
AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3972 7618 3976 7609 3987 7601 3997 7600
      4013 7592 3998 7546 3996 7547 3993 7543
      3987 7542 3967 7553 3962 7560 3960 7560
      3960 7557 3956 7560
TIME...MOT...LOC 2257Z 288DEG 34KT 3982 7599

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
May 14, 7:00 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	60 min
May 14, 7:08 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	67 min
May 14, 7:27 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	63 min
May 14, 3:52 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	53 min
May 14, 4:18 PM EDT	Special Weather Statement	PHI	Carbon	57 min
May 14, 4:26 PM EDT	Special Weather Statement	PHI	Carbon, Northampton	64 min
May 14, 4:42 PM EDT	Severe Thunderstorm Warning	PHI	Berks	63 min
May 14, 5:04 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Northampton	56 min
May 14, 5:07 PM EDT	Special Weather Statement	PHI	Northampton	53 min
May 14, 5:38 PM EDT	Tornado Warning	PHI	Berks, Lehigh	37 min
May 14, 5:49 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	56 min
May 14, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Lehigh, Northampton	67 min
May 14, 6:11 PM EDT	Special Weather Statement	PHI	Carbon	64 min
May 14, 6:25 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Montgomery, Philadelphia	65 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2010 Severe Thunderstorm Warnings in Delaware, 2010 Severe Thunderstorm Warnings in Maryland, 2010 Every severe thunderstorm warning in 2010

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.