Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 85, NWS Philadelphia/Mount Holly

July 13, 2017Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 13, 2017, 5:08 PM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 35 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: Jul 13, 2017, 5:08 PM EDT (21:08 UTC)
Expired: Jul 13, 2017, 5:43 PM EDT
In force: 35 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 100 km from the middle of the area, began a volume at 21:07 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 13, 2:57 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.1 hours before the alert went out and 194 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: 135 J/kg
Mixed-layer CIN: -77 J/kg
Mixed-layer LCL: 1715 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 49 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

943 
WUUS51 KPHI 132108
SVRPHI
PAC029-045-091-132215-
/O.NEW.KPHI.SV.W.0085.170713T2108Z-170713T2215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
508 PM EDT THU JUL 13 2017

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  South central Montgomery County in southeastern Pennsylvania...
  East central Chester County in southeastern Pennsylvania...
  Central Delaware County in southeastern Pennsylvania...

* Until 615 PM EDT

* At 508 PM EDT, a severe thunderstorm was located over Downingtown,
  or 7 miles northwest of West Chester, moving east at 25 mph.

  HAZARD...60 mph wind gusts and quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Minor damage to vehicles is possible. Expect damage to 
           trees and power lines. 

* Locations impacted include...
  West Chester, Downingtown, Conshohocken, Folcroft, Swarthmore, Bryn
  Mawr, Trout Lake, Radnor Township, Lionville-Marchwood, Gradyville,
  Broomall, Paoli, Newtown Square, Lionville, Drexel Hill, Lima,
  Darby Township, Nether Providence Township, King Of Prussia and
  West Goshen.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3997 7579 4007 7580 4008 7527 3990 7528
TIME...MOT...LOC 2108Z 273DEG 20KT 4001 7573 

HAIL...1.00IN
WIND...60MPH
 
$$

MWG

1 follow-up statement

813 
WWUS51 KPHI 132143
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
543 PM EDT THU JUL 13 2017

PAC029-045-091-132152-
/O.CAN.KPHI.SV.W.0085.000000T0000Z-170713T2215Z/
Montgomery PA-Chester PA-Delaware PA-
543 PM EDT THU JUL 13 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL MONTGOMERY...
EAST CENTRAL CHESTER AND CENTRAL DELAWARE COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore the warning has been cancelled.

A severe thunderstorm watch remains in effect until 900 PM EDT for
southeastern Pennsylvania.

LAT...LON 3997 7579 4007 7580 4008 7527 3990 7528
TIME...MOT...LOC 2140Z 273DEG 20KT 4000 7548 

$$

MWG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 13, 3:25 PM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh, Monroe, Northampton	4 hr
Jul 13, 3:30 PM EDT	Special Weather Statement	PHI	Lehigh, Northampton	45 min
Jul 13, 4:06 PM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Monroe, Northampton	114 min
Jul 13, 4:06 PM EDT	Special Weather Statement	PHI	Northampton	39 min
Jul 13, 4:08 PM EDT	Special Weather Statement	PHI	Schuylkill	37 min
Jul 13, 4:09 PM EDT	Special Weather Statement	PHI	Montgomery	36 min
Jul 13, 4:15 PM EDT	Severe Thunderstorm Warning	PHI	Berks	60 min
Jul 13, 4:34 PM EDT	Special Weather Statement	PHI	Chester	41 min
Jul 13, 4:36 PM EDT	Special Weather Statement	PHI	Lehigh	24 min
Jul 13, 4:42 PM EDT	Special Weather Statement	PHI	Montgomery, Philadelphia	48 min
Jul 13, 4:50 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Chester, Montgomery	115 min
Jul 13, 4:50 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	40 min
Jul 13, 5:07 PM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	7 hr
Jul 13, 5:08 PM EDT	Tornado Warning	PHI	Berks	22 min
Jul 13, 5:21 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Philadelphia	54 min
Jul 13, 5:25 PM EDT	Flash Flood Warning	PHI	Berks, Lehigh	3 hr
Jul 13, 5:26 PM EDT	Tornado Warning	PHI	Berks, Chester, Montgomery	28 min
Jul 13, 5:30 PM EDT	Special Weather Statement	PHI	Delaware, Philadelphia	45 min
Jul 13, 5:31 PM EDT	Flash Flood Warning	PHI	Bucks	3 hr
Jul 13, 5:36 PM EDT	Special Weather Statement	PHI	Montgomery	39 min
Jul 13, 5:44 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	46 min
Jul 13, 5:56 PM EDT	Special Weather Statement	PHI	Berks	34 min
Jul 13, 6:28 PM EDT	Special Weather Statement	PHI	Bucks	47 min
Jul 13, 6:34 PM EDT	Special Weather Statement	PHI	Delaware, Montgomery, Philadelphia	41 min
Jul 13, 7:03 PM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	117 min
Jul 13, 7:12 PM EDT	Special Weather Statement	PHI	Philadelphia	48 min
Jul 13, 7:26 PM EDT	Special Weather Statement	PHI	Berks, Montgomery	64 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2017 Every severe thunderstorm warning in 2017

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.