Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 9, NWS Philadelphia/Mount Holly

April 1, 2023Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Apr 1, 2023, 6:04 PM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 56 min. 11 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: Apr 1, 2023, 6:04 PM EDT (22:04 UTC)
Expired: Apr 1, 2023, 7:00 PM EDT
In force: 56 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, Montgomery County, PA

The radar

The Dover AFB radar (KDOX), 123 km from the middle of the area, began a volume at 22:04 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
Apr 1, 6:25 PM EDT	HAIL 0.7	Malvern, PA
Apr 1, 6:30 PM EDT	TSTM WND DMG	Honey Brook, PA	PICTURE OF LARGE TREES DOWNED IN HONEY BROOK, PA. TIME ESTIMATED VIA RADAR.
Apr 1, 6:35 PM EDT	HAIL 0.25	1 W East Whiteland Twp, PA
Apr 1, 6:39 PM EDT	HAIL 0.5	1 Sw Downington, PA	REPORT FROM MPING: HALF-INCH (0.50 IN.).
Apr 1, 6:40 PM EDT	TSTM WND DMG	1 Sw Whitemarsh Twp, PA	LARGE TREE DOWN ON BARREN HILL ROAD JUST WEST OF RIDGE PIKE.
Apr 1, 6:40 PM EDT	HAIL 1	2 Sse Upper Uwchlan Twp, PA	REPORT FROM MPING: QUARTER (1.00 IN.).
Apr 1, 6:42 PM EDT	TSTM WND DMG	1 Ne King Of Prussia, PA	US-422 CLOSED IN BOTH DIRECTIONS BETWEEN THE PA-23 BRIDGEPORT AND PA 363 AT AUDUBON EXITS IN UPPER MERION TOWNSHIP, MONTGOMERY COUNTY DUE TO DOWNED UTILITY LINES. TIME ESTIMATED VIA RADAR.
Apr 1, 6:43 PM EDT	HAIL 0.5	1 W King Of Prussia, PA	REPORT FROM MPING: HALF-INCH (0.50 IN.).
Apr 1, 6:44 PM EDT	TSTM WND DMG	1 Ssw Whitemarsh Twp, PA	REPORT FROM MPING: TREES UPROOTED OR SNAPPED; ROOF BLOWN OFF. TIME CORRECTED BASED ON RADAR.
Apr 1, 6:44 PM EDT	HAIL 0.5	Oxford, PA	REPORT FROM MPING: HALF-INCH (0.50 IN.).
Apr 1, 6:46 PM EDT	HAIL 0.5	1 S King Of Prussia, PA	REPORT FROM MPING: HALF-INCH (0.50 IN.).

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

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

Issued	Product	Office	Lasted
Apr 1, 5:30 PM EDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.1 hours before the alert went out and 163 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 648 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 448 m²/s²
0-3 km storm-relative helicity: 443 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

127 
WUUS51 KPHI 012204
SVRPHI
PAC029-045-091-012300-
/O.NEW.KPHI.SV.W.0009.230401T2204Z-230401T2300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
604 PM EDT Sat Apr 1 2023

The National Weather Service in Mount Holly NJ has issued a

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

* Until 700 PM EDT.

* At 604 PM EDT, severe thunderstorms were located along a line
  extending from Churchtown to near Smithville, moving east at 45
  mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  West Chester, Coatesville, Westtown, Downingtown, Conshohocken,
  Kennett Square, Oxford, Parkesburg, West Grove, Honey Brook,
  Homeville, Glen Roy, Cochranville, Cheyney, Mount Vernon,
  Marshallton, Radnor Township, Lionville-Marchwood, Gradyville and
  Valley Forge.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 302 and 330.
 Interstate 76 in Pennsylvania between mile markers 327 and 334.
 Interstate 476 in Pennsylvania between mile markers 11 and 18.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1000 PM EDT for northern
Delaware...and southeastern Pennsylvania.

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

A Tornado Watch remains in effect until 1000 PM EDT for northern
Delaware...and southeastern Pennsylvania.

&&

LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
      3983 7604 3987 7599 3995 7600 4004 7593
      4011 7594 4015 7585 4009 7524 3983 7561
      3981 7570 3972 7577 3972 7613
TIME...MOT...LOC 2204Z 276DEG 38KT 4015 7593 3991 7630 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Staarmann

1 follow-up statement

607 
WWUS51 KPHI 012226
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
626 PM EDT Sat Apr 1 2023

PAC029-045-091-012300-
/O.CON.KPHI.SV.W.0009.000000T0000Z-230401T2300Z/
Montgomery PA-Chester PA-Delaware PA-
626 PM EDT Sat Apr 1 2023

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 700 PM EDT
FOR SOUTH CENTRAL MONTGOMERY...CHESTER AND NORTHWESTERN DELAWARE
COUNTIES...

At 626 PM EDT, severe thunderstorms were located along a line
extending from near Glenmoore to Glen Roy, moving east at 40 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
West Chester, Coatesville, Westtown, Downingtown, Conshohocken,
Kennett Square, Oxford, Parkesburg, West Grove, Honey Brook,
Homeville, Glen Roy, Cochranville, Cheyney, Mount Vernon,
Marshallton, Radnor Township, Lionville-Marchwood, Gradyville and
Valley Forge.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 302 and 330.
 Interstate 76 in Pennsylvania between mile markers 327 and 334.
 Interstate 476 in Pennsylvania between mile markers 11 and 18.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1000 PM EDT for northern
Delaware...and southeastern Pennsylvania.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

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

&&

LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
      3983 7604 3987 7599 3995 7600 4004 7593
      4011 7594 4015 7585 4009 7524 3983 7561
      3981 7570 3972 7577 3972 7613
TIME...MOT...LOC 2226Z 274DEG 37KT 4008 7571 3975 7607 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Staarmann

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 1, 5:27 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Carbon, Lehigh, Northampton	48 min
Apr 1, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery, Northampton	67 min
Apr 1, 6:33 PM EDT	Tornado Warning	PHI	Chester	27 min
Apr 1, 6:37 PM EDT	Severe Thunderstorm Warning Considerable damage threat	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	53 min
Apr 1, 6:39 PM EDT	Severe Thunderstorm Warning Considerable damage threat	PHI	Chester, Delaware	51 min
Apr 1, 6:45 PM EDT	Tornado Warning	PHI	Bucks	30 min
Apr 1, 6:57 PM EDT	Tornado Warning	PHI	Philadelphia	33 min
Apr 1, 7:11 PM EDT	Severe Thunderstorm Warning Considerable damage threat	PHI	Philadelphia	64 min

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.