Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2010

Severe Thunderstorm Warning 47, NWS Philadelphia/Mount Holly

May 27, 2010New Castle County, Delaware; Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 27, 2010, 7:56 PM EDT for New Castle County, Delaware; Chester County, Delaware County, Pennsylvania. It was in force for 34 min. 4 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 27, 2010, 7:56 PM EDT (23:56 UTC)
Expired: May 27, 2010, 8:30 PM EDT
In force: 34 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

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

The radar

The Philadelphia radar (KDIX), 100 km from the middle of the area, began a volume at 23:59 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 27, 8:01 PM EDT	HAIL 0.5	1 Sw West Chester, PA	DIME SIZE HAIL REPORTED IN EAST BRADFORD TOWNSHIP.
May 27, 8:35 PM EDT	HAIL 1	Talleyville, DE
May 27, 8:35 PM EDT	HAIL 1	Wilmington, DE	QUARTER SIZE HAIL REPORTED IN WILMINGTON.
May 27, 8:38 PM EDT	HAIL 0.88	N Wilmington, DE	NICKEL TO DIME SIZED HAIL COVERING THE GROUND.

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 27, 1:23 PM EDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 11.9 hours before the alert went out and 62 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: 759 J/kg
Mixed-layer CIN: -227 J/kg
Mixed-layer LCL: 1358 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: -74 m²/s²
0-3 km storm-relative helicity: 53 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

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

242 
WUUS51 KPHI 272356
SVRPHI
DEC003-PAC029-045-280030-
/O.NEW.KPHI.SV.W.0047.100527T2356Z-100528T0030Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
756 PM EDT THU MAY 27 2010

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...
  THIS INCLUDES THE CITY OF WILMINGTON...
  CENTRAL CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...
  SOUTHWESTERN DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 830 PM EDT

* AT 754 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL.  THIS
  STORM WAS LOCATED NEAR MARSHALLTON...OR NEAR WEST CHESTER...AND
  MOVING SOUTH AT 15 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  MARSHALLTON AND WEST CHESTER AROUND 800 PM EDT...
  WESTTOWN AND 7 MILES WEST OF CHEYNEY AROUND 810 PM EDT...
  6 MILES WEST OF CONCORDVILLE AROUND 820 PM EDT...
  KENNETT SQUARE AROUND 825 PM EDT...
  ASHLAND...TALLEYVILLE...ELAM AND HOCKESSIN AROUND 830 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THE STORM IS PRODUCING ABUNDANT AMOUNTS OF LIGHTNING. GO INDOORS 
WHEN THUNDERSTORMS APPROACH. 

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT
THURSDAY EVENING FOR NORTHERN DELAWARE AND NORTHEASTERN MARYLAND AND
NEW JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 4009 7560 3977 7545 3976 7547 3972 7548
      3971 7550 3968 7574 4006 7576
TIME...MOT...LOC 2355Z 349DEG 15KT 3998 7566

$$

PO

1 follow-up statement

502 
WWUS51 KPHI 280010
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
810 PM EDT THU MAY 27 2010

DEC003-PAC029-045-280030-
/O.CON.KPHI.SV.W.0047.000000T0000Z-100528T0030Z/
DELAWARE PA-CHESTER PA-NEW CASTLE DE-
810 PM EDT THU MAY 27 2010

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 830 PM EDT
FOR NORTHEASTERN NEW CASTLE...CENTRAL CHESTER AND SOUTHWESTERN
DELAWARE COUNTIES...

AT 807 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL.  THIS STORM WAS LOCATED NEAR WESTTOWN...OR NEAR WEST CHESTER...
MOVING SOUTHEAST AT 25 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  ELAM...6 MILES NORTHEAST OF ASHLAND AND 8 MILES NORTHEAST OF
  HOCKESSIN BY 820 PM EDT...
  TALLEYVILLE BY 825 PM EDT...
  ARDENCROFT...ARDEN...BELLEFONTE AND ARDENTOWN BY 830 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT
THURSDAY EVENING FOR NORTHERN DELAWARE AND NORTHEASTERN MARYLAND AND
NEW JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3994 7568 3996 7557 3977 7545 3976 7547
      3972 7548 3971 7550 3968 7571
TIME...MOT...LOC 0010Z 331DEG 22KT 3990 7560

$$

PO

The office that day

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

Issued	Product	Office	Counties	Lasted
May 27, 4:05 AM EDT	Coastal Flood Advisory	PHI	Sussex	19 hr
May 27, 2:00 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Monroe, Northampton	60 min
May 27, 2:30 PM EDT	Flash Flood Warning	PHI	Northampton	33 min
May 27, 2:45 PM EDT	Special Weather Statement	PHI	Chester	60 min
May 27, 3:19 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Northampton	41 min
May 27, 4:53 PM EDT	Special Weather Statement	PHI	Bucks, Montgomery	52 min
May 27, 5:11 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Carbon, Lehigh, Northampton	64 min
May 27, 5:36 PM EDT	Severe Thunderstorm Warning	PHI	Monroe, Northampton	54 min
May 27, 5:44 PM EDT	Special Weather Statement	PHI	Delaware, Montgomery	61 min
May 27, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery	37 min
May 27, 6:05 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Lehigh, Montgomery	25 min
May 27, 6:20 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Lehigh, Montgomery	55 min
May 27, 6:35 PM EDT	Special Weather Statement	PHI	Northampton	55 min
May 27, 7:12 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Delaware, Montgomery	48 min
May 27, 7:25 PM EDT	Special Weather Statement	PHI	Montgomery	65 min
May 27, 7:40 PM EDT	Special Weather Statement	PHI	Bucks	65 min
May 27, 7:44 PM EDT	Areal Flood Advisory	PHI	Berks, Chester, Montgomery	3 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2010 Severe Thunderstorm Warnings in Delaware, 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.