Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 286, NWS Philadelphia/Mount Holly

August 12, 2023Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 12, 2023, 4:06 PM EDT for Chester County, Delaware County, Pennsylvania. It was in force for 39 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: Aug 12, 2023, 4:06 PM EDT (20:06 UTC)
Expired: Aug 12, 2023, 4:45 PM EDT
In force: 39 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Chester County, PA, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 118 km from the middle of the area, began a volume at 20:06 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
Aug 12, 4:43 PM EDT	TSTM WND DMG	1 Ene Newlin Twp, PA	Trees and wires down on Unionville Wawaset Road. Time estimated from radar.

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, 8.1 hours before the alert went out and 183 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: 176 J/kg
Mixed-layer CIN: -108 J/kg
Mixed-layer LCL: 1236 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 103 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

252 
WUUS51 KPHI 122006
SVRPHI
PAC029-045-122045-
/O.NEW.KPHI.SV.W.0286.230812T2006Z-230812T2045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
406 PM EDT Sat Aug 12 2023

The National Weather Service in Mount Holly NJ has issued a

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

* Until 445 PM EDT.

* At 406 PM EDT, a severe thunderstorm was located near Honey Brook,
  or 11 miles east of New Holland, moving east at 20 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, Westtown, Downingtown, Parkesburg, Honey
  Brook, Gradyville, Cheyney, Glenmoore, Paoli, Chester Springs,
  Lionville, Marshallton, Concordville, Lionville-Marchwood, West
  Goshen, Malvern, South Coatesville, Modena and Exton.

This includes Pennsylvania Turnpike between mile markers 306 and 322.
 
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 4004 7593 4011 7594 4013 7589 4007 7541
      3987 7550 3997 7598
TIME...MOT...LOC 2006Z 286DEG 19KT 4004 7588 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Hoeflich

2 follow-up statements

911 
WWUS51 KPHI 122027
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
427 PM EDT Sat Aug 12 2023

PAC029-045-122045-
/O.CON.KPHI.SV.W.0286.000000T0000Z-230812T2045Z/
Chester PA-Delaware PA-
427 PM EDT Sat Aug 12 2023

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM EDT
FOR CENTRAL CHESTER AND WEST CENTRAL DELAWARE COUNTIES...

At 427 PM EDT, a severe thunderstorm was located near Coatesville, or
8 miles west of West Chester, moving southeast at 25 mph.

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

SOURCE...Radar indicated.

IMPACT...Minor damage to vehicles is possible. Wind damage to roofs, 
         siding, trees, and power lines is possible.

Locations impacted include...
West Chester, Coatesville, Westtown, Downingtown, Gradyville,
Cheyney, Marshallton, Concordville, Lionville-Marchwood, West Goshen,
South Coatesville, Modena, Exton and Thorndale.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3995 7588 4008 7576 3998 7545 3987 7550
TIME...MOT...LOC 2027Z 311DEG 21KT 3996 7576 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Hoeflich

030 
WWUS51 KPHI 122039
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
439 PM EDT Sat Aug 12 2023

PAC029-045-122048-
/O.EXP.KPHI.SV.W.0286.000000T0000Z-230812T2045Z/
Chester PA-Delaware PA-
439 PM EDT Sat Aug 12 2023

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL CHESTER AND WEST
CENTRAL DELAWARE COUNTIES WILL EXPIRE AT 445 PM EDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire. A new Severe 
Thunderstorm Warning was re-issued for central Chester County and 
southern Delaware County until 5:15 PM EDT. 



LAT...LON 3995 7588 4008 7576 3998 7545 3987 7550
TIME...MOT...LOC 2038Z 286DEG 19KT 3995 7570 

$$

Hoeflich

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 12, 12:57 PM EDT	Areal Flood Advisory	PHI	Delaware, Philadelphia	3 hr
Aug 12, 1:38 PM EDT	Areal Flood Advisory	PHI	Delaware, Philadelphia	3 hr
Aug 12, 3:06 PM EDT	Special Weather Statement	PHI	Berks	24 min
Aug 12, 3:39 PM EDT	Special Weather Statement	PHI	Berks	36 min
Aug 12, 3:49 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	41 min
Aug 12, 3:55 PM EDT	Special Weather Statement	PHI	Chester	35 min
Aug 12, 4:37 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	38 min
Aug 12, 4:57 PM EDT	Severe Thunderstorm Warning	PHI	Carbon	48 min
Aug 12, 5:05 PM EDT	Areal Flood Advisory	PHI	Chester	3 hr
Aug 12, 5:16 PM EDT	Special Weather Statement	PHI	Delaware	29 min
Aug 12, 5:31 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	44 min
Aug 12, 6:42 PM EDT	Special Weather Statement	PHI	Montgomery	33 min
Aug 12, 6:47 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery	28 min
Aug 12, 6:58 PM EDT	Areal Flood Advisory	PHI	Chester	3 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2023 Every severe thunderstorm warning in 2023

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.