Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 61, NWS Philadelphia/Mount Holly

July 27, 2018Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 27, 2018, 7:09 PM EDT for Chester County, Pennsylvania. It was in force for 51 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 27, 2018, 7:09 PM EDT (23:09 UTC)
Expired: Jul 27, 2018, 8:00 PM EDT
In force: 51 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 121 km from the middle of the area, began a volume at 23:13 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 27, 1:17 PM EDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.2 hours before the alert went out and 182 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: 958 J/kg
Mixed-layer CIN: -54 J/kg
Mixed-layer LCL: 1053 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 34 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

777 
WUUS51 KPHI 272309
SVRPHI
PAC029-280000-
/O.NEW.KPHI.SV.W.0061.180727T2309Z-180728T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
709 PM EDT FRI JUL 27 2018

The National Weather Service in Mount Holly NJ has issued a

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

* Until 800 PM EDT.

* At 708 PM EDT, a severe thunderstorm was located near Honey Brook,
  or 12 miles east of New Holland, moving east at 40 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  West Chester, Coatesville, Downingtown, Parkesburg, Honey Brook,
  Elverson, Homeville, Cochranville, Pughtown, Marshallton,
  Lionville-Marchwood, Glenmoore, Chester Springs, Lionville,
  Cedarville, West Goshen, Stowe, Atglen, South Coatesville and
  Christiana.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3987 7599 3992 7600 3994 7598 3995 7600
      4004 7593 4011 7594 4014 7587 4024 7570
      4024 7565 4022 7561 4024 7560 4020 7557
      3986 7560 3986 7601
TIME...MOT...LOC 2308Z 275DEG 34KT 4004 7587 

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

CMS

2 follow-up statements

983 
WWUS51 KPHI 272332
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
732 PM EDT FRI JUL 27 2018

PAC029-280000-
/O.CON.KPHI.SV.W.0061.000000T0000Z-180728T0000Z/
Chester PA-
732 PM EDT FRI JUL 27 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 800 PM EDT
FOR NORTH CENTRAL CHESTER COUNTY...

At 732 PM EDT, a severe thunderstorm was located over Lionville, or 8
miles northwest of West Chester, moving east at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
West Chester, Coatesville, Downingtown, Honey Brook, Elverson,
Glenmoore, Chester Springs, Pughtown, Lionville, Cedarville,
Lionville-Marchwood, West Goshen, Stowe, South Coatesville, Modena,
Exton, South Pottstown, Thorndale and Kenilworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3994 7588 4012 7593 4014 7587 4024 7570
      4024 7565 4022 7561 4024 7560 4020 7557
      3996 7559
TIME...MOT...LOC 2332Z 263DEG 24KT 4008 7567 

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

CMS

038 
WWUS51 KPHI 272350
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
750 PM EDT FRI JUL 27 2018

PAC029-280000-
/O.EXP.KPHI.SV.W.0061.000000T0000Z-180728T0000Z/
Chester PA-
750 PM EDT FRI JUL 27 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL CHESTER COUNTY
WILL EXPIRE AT 800 PM EDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.  However gusty winds and heavy rain are still
possible with this thunderstorm.

A severe thunderstorm watch remains in effect until 1000 PM EDT for
eastern and southeastern Pennsylvania.

LAT...LON 3994 7588 4012 7593 4014 7587 4024 7570
      4024 7565 4022 7561 4024 7560 4020 7557
      3996 7559
TIME...MOT...LOC 2350Z 275DEG 34KT 4007 7545 

$$

CMS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 27, 9:50 AM EDT	Flash Flood Watch	PHI	Berks, Bucks, Carbon, Chester, Delaware, Lehigh and 4 more	13 hr
Jul 27, 12:17 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	2 hr
Jul 27, 12:35 PM EDT	Flash Flood Warning	PHI	Monroe	63 min
Jul 27, 1:02 PM EDT	Areal Flood Advisory	PHI	Berks	3 hr
Jul 27, 1:08 PM EDT	Special Weather Statement	PHI	Bucks, Montgomery	37 min
Jul 27, 1:19 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery	4 hr
Jul 27, 1:42 PM EDT	Special Weather Statement	PHI	Montgomery	48 min
Jul 27, 3:11 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	49 min
Jul 27, 3:47 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	4 hr
Jul 27, 3:54 PM EDT	Flash Flood Warning	PHI	Berks	4 hr
Jul 27, 4:27 PM EDT	Special Weather Statement	PHI	Philadelphia	33 min
Jul 27, 4:33 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	27 min
Jul 27, 4:43 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	5 hr
Jul 27, 4:44 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	7 hr
Jul 27, 5:00 PM EDT	Flash Flood Warning	PHI	Monroe	3 hr
Jul 27, 5:13 PM EDT	Special Weather Statement	PHI	Monroe	47 min
Jul 27, 5:27 PM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh, Northampton	4 hr
Jul 27, 5:43 PM EDT	Special Weather Statement	PHI	Lehigh	47 min
Jul 27, 6:03 PM EDT	Severe Thunderstorm Warning	PHI	Chester	42 min
Jul 27, 6:06 PM EDT	Areal Flood Advisory	PHI	Berks, Chester	3 hr
Jul 27, 6:36 PM EDT	Special Weather Statement	PHI	Berks	39 min
Jul 27, 6:40 PM EDT	Severe Thunderstorm Warning	PHI	Berks	50 min
Jul 27, 7:03 PM EDT	Flash Flood Warning	PHI	Berks	3 hr
Jul 27, 7:37 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery	116 min
Jul 27, 7:46 PM EDT	Special Weather Statement	PHI	Montgomery	44 min
Jul 27, 7:49 PM EDT	Areal Flood Warning	PHI	Berks	4 hr
Jul 27, 7:49 PM EDT	Special Weather Statement	PHI	Berks	41 min
Jul 27, 7:53 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh, Montgomery	110 min
Jul 27, 7:55 PM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Montgomery, Northampton	108 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2018 Every severe thunderstorm warning in 2018

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.