Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 116, NWS Philadelphia/Mount Holly

July 22, 20175 counties in Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 22, 2017, 5:18 PM EDT for 5 counties in Pennsylvania; New Castle County, Delaware. It was in force for 42 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: Jul 22, 2017, 5:18 PM EDT (21:18 UTC)
Expired: Jul 22, 2017, 6:00 PM EDT
In force: 42 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties New Castle County, DE, Berks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 114 km from the middle of the area, began a volume at 21:20 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
Jul 22, 5:40 PM EDT	TSTM WND DMG	Exton, PA	TREE DOWN ON SHIP ROAD AND PULLMAN DRIVE..
Jul 22, 5:45 PM EDT	TSTM WND DMG	West Goshen, PA	WIRES DOWN ON ASHBRIDGE ROAD.
Jul 22, 5:50 PM EDT	TSTM WND DMG	Willistown Twp, PA	TREE AND WIRES DOWN ON DUTTON MILL ROAD.
Jul 22, 5:59 PM EDT	TSTM WND DMG	Lower Providence Twp, PA	LARGE TREE DOWN ON CROSSKEYS ROAD
Jul 22, 6:00 PM EDT	TSTM WND DMG	Norristown, PA	WIRES DOWN AT DEKALB AND FORNANCE STREETS.
Jul 22, 6:00 PM EDT	TSTM WND DMG	Wayne, PA	TREES DOWN.

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, 9.3 hours before the alert went out and 188 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: 107 J/kg
Mixed-layer CIN: -100 J/kg
Mixed-layer LCL: 1084 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: 68 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

664 
WUUS51 KPHI 222118
SVRPHI
DEC003-PAC011-029-045-091-101-222200-
/O.NEW.KPHI.SV.W.0116.170722T2118Z-170722T2200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
518 PM EDT SAT JUL 22 2017

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  North central New Castle County in northern Delaware...
  South central Berks County in eastern Pennsylvania...
  Southern Montgomery County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...
  Northwestern Philadelphia County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 600 PM EDT

* At 516 PM EDT, severe thunderstorms were located along a line
  extending from near Elverson to near Parkesburg, moving southeast
  at 30 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Doppler radar and emergency management. Lancaster County 
           911 center reported downed trees when the storm moved 
           through Ephrata and New Holland. 

  IMPACT...Expect damage to trees and power lines. 

* Locations impacted include...
  Philadelphia, Wilmington, West Chester, Norristown, Chester,
  Phoenixville, West Norriton, East Norriton, Coatesville, Westtown,
  Downingtown, Conshohocken, Swarthmore, Kennett Square,
  Collegeville, Royersford, Jenkintown, Narberth, Parkesburg and East
  Lansdowne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to damaging winds...frequent cloud to ground lightning 
is occurring with this storm. Move indoors immediately. 
Remember...if you can hear thunder...you are close enough to be 
struck by lightning.

Torrential rainfall is occurring with these storms, and may lead to
flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4004 7593 4011 7594 4014 7588 4017 7592
      4024 7585 4012 7507 3987 7535 3976 7553
      3999 7597
TIME...MOT...LOC 2116Z 292DEG 28KT 4018 7581 4001 7593 

HAIL...<.75IN
WIND...60MPH
 
$$

JRK

2 follow-up statements

444 
WWUS51 KPHI 222141
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
541 PM EDT SAT JUL 22 2017

PAC011-222151-
/O.CAN.KPHI.SV.W.0116.000000T0000Z-170722T2200Z/
Berks PA-
541 PM EDT SAT JUL 22 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL BERKS COUNTY IS
CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

LAT...LON 3978 7549 3990 7569 4000 7573 4017 7559
      4009 7510 3987 7535
TIME...MOT...LOC 2141Z 292DEG 30KT 4011 7556 3994 7568 

$$

DEC003-PAC029-045-091-101-222200-
/O.CON.KPHI.SV.W.0116.000000T0000Z-170722T2200Z/
New Castle DE-Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
541 PM EDT SAT JUL 22 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM EDT
FOR NORTH CENTRAL NEW CASTLE...SOUTHEASTERN MONTGOMERY...NORTHEASTERN
CHESTER...NORTHWESTERN PHILADELPHIA AND DELAWARE COUNTIES...

At 541 PM EDT, severe thunderstorms were located along a line
extending from near Phoenixville to Marshallton, moving east at 35
mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to trees and power lines. 

Locations impacted include...
Philadelphia, West Chester, Norristown, Chester, Phoenixville, West
Norriton, Westtown, Downingtown, Conshohocken, Swarthmore,
Jenkintown, Narberth, East Lansdowne, Arden, Cheyney, Morris Park,
Elam, Bryn Mawr, Marshallton and Trout Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition damaging winds...frequent cloud to ground lightning is 
occurring with this storm. Move indoors immediately. Remember...if 
you can hear thunder...you are close enough to be struck by 
lightning.

Torrential rainfall is occurring with these storms, and may lead to 
flooding in poor drainage areas. Do not drive your vehicle through 
flooded roadways.

&&

LAT...LON 3978 7549 3990 7569 4000 7573 4017 7559
      4009 7510 3987 7535
TIME...MOT...LOC 2141Z 292DEG 30KT 4011 7556 3994 7568 

HAIL...<.75IN
WIND...60MPH
 
$$

JRK

383 
WWUS51 KPHI 222153
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
553 PM EDT SAT JUL 22 2017

DEC003-222202-
/O.CAN.KPHI.SV.W.0116.000000T0000Z-170722T2200Z/
New Castle DE-
553 PM EDT SAT JUL 22 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN NEW CASTLE COUNTY
IS CANCELLED...

The storms which prompted the warning will pass to the north of the 
Delaware-Pennsylvania border. Therefore, the warning has been 
cancelled.

LAT...LON 3984 7540 3995 7562 4015 7548 4015 7547
      4009 7510 3987 7535
TIME...MOT...LOC 2152Z 283DEG 30KT 4012 7542 3995 7554 

$$

PAC029-045-091-101-222200-
/O.CON.KPHI.SV.W.0116.000000T0000Z-170722T2200Z/
Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
553 PM EDT SAT JUL 22 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM EDT
FOR SOUTHEASTERN MONTGOMERY...EAST CENTRAL CHESTER...NORTHWESTERN
PHILADELPHIA AND DELAWARE COUNTIES...

At 552 PM EDT, severe thunderstorms were located along a line
extending from near West Norriton to Westtown, moving east at 35 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to trees and power lines. 

Locations impacted include...
Philadelphia, West Chester, Norristown, Chester, West Norriton,
Westtown, Conshohocken, Swarthmore, Jenkintown, Narberth, East
Lansdowne, Cheyney, Morris Park, Bryn Mawr, Trout Lake, Radnor
Township, Gradyville, Broomall, Newtown Square and Chester Township.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with these storms, and may lead to 
poor drainage flooding. Do not drive your vehicle through flooded 
roadways.

&&

LAT...LON 3984 7540 3995 7562 4015 7548 4015 7547
      4009 7510 3987 7535
TIME...MOT...LOC 2152Z 283DEG 30KT 4012 7542 3995 7554 

HAIL...<.75IN
WIND...60MPH
 
$$

JRK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 22, 3:58 PM EDT	Special Weather Statement	PHI	Berks	62 min
Jul 22, 4:11 PM EDT	Areal Flood Advisory	PHI	Berks	4 hr
Jul 22, 4:57 PM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	4 hr
Jul 22, 5:03 PM EDT	Special Weather Statement	PHI	Bucks, Chester, Montgomery	42 min
Jul 22, 5:50 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	55 min
Jul 22, 6:00 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	3 hr
Jul 22, 6:38 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Philadelphia	52 min
Jul 22, 6:46 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Carbon, Lehigh, Monroe, Northampton	4 hr
Jul 22, 7:10 PM EDT	Areal Flood Advisory	PHI	Bucks	4 hr
Jul 22, 10:45 AM EDT	Coastal Flood Advisory	PHI	Kent, Sussex	13 hr
Jul 22, 2:58 PM EDT	Special Weather Statement	PHI	Sussex	62 min
Jul 22, 3:17 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	43 min
Jul 22, 3:34 PM EDT	Special Weather Statement	PHI	Sussex	41 min
Jul 22, 3:36 PM EDT	Areal Flood Advisory	PHI	Sussex	114 min
Jul 22, 3:38 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	52 min
Jul 22, 3:57 PM EDT	Special Weather Statement	PHI	Sussex	33 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2017 Severe Thunderstorm Warnings in Delaware, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.