Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 132, NWS Philadelphia/Mount Holly

July 24, 2017Bucks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 24, 2017, 7:26 PM EDT for Bucks County, Chester County, Montgomery County, Pennsylvania. It was in force for 49 min. 1 report 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 24, 2017, 7:26 PM EDT (23:26 UTC)
Expired: Jul 24, 2017, 8:15 PM EDT
In force: 49 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Bucks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 91 km from the middle of the area, began a volume at 23:26 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 24, 7:40 PM EDT	TSTM WND DMG	West Norriton, PA	TREES AND WIRES 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, 11.4 hours before the alert went out and 221 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: 57 J/kg
Mixed-layer CIN: -164 J/kg
Mixed-layer LCL: 1219 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: -82 m²/s²
0-3 km storm-relative helicity: 17 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

269 
WUUS51 KPHI 242326
SVRPHI
PAC017-029-091-250015-
/O.NEW.KPHI.SV.W.0132.170724T2326Z-170725T0015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service MOUNT HOLLY NJ
726 PM EDT MON JUL 24 2017

The National Weather Service in MOUNT HOLLY NJ  has issued a

* Severe Thunderstorm Warning for...
  Montgomery County in southeastern Pennsylvania...
  Central Bucks County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...

* Until 815 PM EDT

* At 725 PM EDT, a severe thunderstorm was located near Pottstown, or
  20 miles east of Reading, moving east at 35 mph.

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

  SOURCE...Radar indicated. 

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

* Locations impacted include...
  Norristown, Pottstown, Phoenixville, Lansdale, West Norriton, East
  Norriton, Doylestown, Hatboro, Souderton, Ambler, Collegeville,
  Royersford, Chalfont, Trappe, Hatfield, Schwenksville, Green Lane,
  Fricks, Spring Mount and Gilbertsville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to large hail and 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.

&&

LAT...LON 4017 7565 4034 7560 4033 7506 4009 7514
TIME...MOT...LOC 2325Z 278DEG 29KT 4026 7556 

HAIL...0.75IN
WIND...60MPH
 
$$

amc

1 follow-up statement

174 
WWUS51 KPHI 242359
SVSPHI

Severe Weather Statement
National Weather Service MOUNT HOLLY NJ
759 PM EDT MON JUL 24 2017

PAC029-250008-
/O.CAN.KPHI.SV.W.0132.000000T0000Z-170725T0015Z/
Chester PA-
759 PM EDT MON JUL 24 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN CHESTER COUNTY IS
CANCELLED...

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

LAT...LON 4015 7550 4020 7535 4033 7506 4009 7514
      4015 7549 4014 7551 4015 7553
TIME...MOT...LOC 2358Z 282DEG 27KT 4031 7515 4010 7526 

$$

PAC017-091-250015-
/O.CON.KPHI.SV.W.0132.000000T0000Z-170725T0015Z/
Montgomery PA-Bucks PA-
759 PM EDT MON JUL 24 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM EDT
FOR CENTRAL MONTGOMERY AND CENTRAL BUCKS COUNTIES...

At 758 PM EDT, severe thunderstorms were located along a line
extending from Doylestown to Plymouth Meeting, moving east at 30 mph.

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

SOURCE...Radar indicated. 

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

Locations impacted include...
Norristown, Phoenixville, Lansdale, West Norriton, East Norriton,
Doylestown, Hatboro, Ambler, Willow Grove, Plymouth Meeting, Horsham,
North Wales, Fort Washington, Blue Bell, Maple Glen, Eagleville,
Flourtown, Spring House, Montgomeryville and Glenside.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4015 7550 4020 7535 4033 7506 4009 7514
      4015 7549 4014 7551 4015 7553
TIME...MOT...LOC 2358Z 282DEG 27KT 4031 7515 4010 7526 

HAIL...0.75IN
WIND...60MPH
 
$$

amc

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 24, 1:33 AM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	5 hr
Jul 24, 2:34 AM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	41 min
Jul 24, 3:00 AM EDT	Flash Flood Warning	PHI	Delaware, Montgomery, Philadelphia	4 hr
Jul 24, 3:17 AM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Lehigh, Monroe, Montgomery, Northampton	118 min
Jul 24, 3:21 AM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Jul 24, 3:36 AM EDT	Areal Flood Advisory	PHI	Monroe, Northampton	6 hr
Jul 24, 3:47 AM EDT	Areal Flood Advisory	PHI	Carbon, Lehigh, Monroe, Northampton	118 min
Jul 24, 5:23 PM EDT	Special Weather Statement	PHI	Berks	37 min
Jul 24, 5:31 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	59 min
Jul 24, 6:15 PM EDT	Special Weather Statement	PHI	Berks	45 min
Jul 24, 6:30 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Lehigh, Montgomery	60 min
Jul 24, 6:43 PM EDT	Flash Flood Warning	PHI	Berks, Lehigh, Northampton	4 hr
Jul 24, 6:47 PM EDT	Flash Flood Warning	PHI	Berks	4 hr
Jul 24, 7:07 PM EDT	Areal Flood Advisory	PHI	Northampton	113 min
Jul 24, 7:07 PM EDT	Special Weather Statement	PHI	Berks	23 min
Jul 24, 7:12 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Lehigh, Montgomery, Northampton	2 hr
Jul 24, 7:16 PM EDT	Areal Flood Advisory	PHI	Berks, Montgomery	119 min
Jul 24, 7:23 PM EDT	Flash Flood Warning	PHI	Bucks, Lehigh, Montgomery	4 hr
Jul 24, 7:42 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Montgomery	2 hr
Jul 24, 7:48 PM EDT	Areal Flood Advisory	PHI	Bucks	117 min
Jul 24, 7:50 PM EDT	Severe Thunderstorm Warning	PHI	Montgomery, Philadelphia	25 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.