Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 22, NWS Philadelphia/Mount Holly

May 15, 2018Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 15, 2018, 6:15 PM EDT for Chester County, Pennsylvania. It was in force for 60 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: May 15, 2018, 6:15 PM EDT (22:15 UTC)
Expired: May 15, 2018, 7:15 PM EDT
In force: 60 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 Dover AFB radar (KDOX), 121 km from the middle of the area, began a volume at 22:18 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
May 15, 1:46 PM EDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.3 hours before the alert went out and 161 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: 47 J/kg
Mixed-layer CIN: -484 J/kg
Mixed-layer LCL: 1259 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 117 m²/s²
0-3 km storm-relative helicity: 79 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

164 
WUUS51 KPHI 152215
SVRPHI
PAC029-152315-
/O.NEW.KPHI.SV.W.0022.180515T2215Z-180515T2315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
615 PM EDT TUE MAY 15 2018

The National Weather Service in Mount Holly NJ has issued a

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

* Until 715 PM EDT.

* At 615 PM EDT, a severe thunderstorm was located over Cochranville,
  or 16 miles west of West Chester, moving east at 55 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, Kennett Square,
  Oxford, Parkesburg, West Grove, Homeville, Glen Roy, Cochranville,
  Mount Vernon, Marshallton, Ladenberg, Kemblesville, Hockessin,
  North Star, West Goshen, Malvern and Atglen.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3977 7606 3981 7603 3983 7604 3983 7602
      3985 7602 3987 7599 3992 7600 3994 7598
      3995 7600 4000 7596 4003 7543 3982 7565
      3977 7574 3972 7577 3972 7608
TIME...MOT...LOC 2215Z 260DEG 49KT 3991 7590 

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

po

1 follow-up statement

121 
WWUS51 KPHI 152307
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
707 PM EDT TUE MAY 15 2018

PAC029-152316-
/O.EXP.KPHI.SV.W.0022.000000T0000Z-180515T2315Z/
Chester PA-
707 PM EDT TUE MAY 15 2018

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN CHESTER COUNTY WILL
EXPIRE AT 715 PM EDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

A severe thunderstorm watch remains in effect until 1100 PM EDT for
northern Delaware...northeastern Maryland...and southeastern
Pennsylvania.

LAT...LON 3977 7606 3981 7603 3983 7604 3983 7602
      3985 7602 3987 7599 3992 7600 3994 7598
      3995 7600 4000 7596 4003 7543 3982 7565
      3977 7574 3972 7577 3972 7608
TIME...MOT...LOC 2306Z 260DEG 49KT 4003 7502 

$$

PO

The office that day

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

Issued	Product	Office	Counties	Lasted
May 15, 3:40 AM EDT	Flash Flood Watch	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 1 more	21 hr
May 15, 2:49 PM EDT	Special Weather Statement	PHI	Berks, Carbon, Lehigh, Monroe, Northampton	56 min
May 15, 3:20 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe	55 min
May 15, 3:46 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh, Northampton	74 min
May 15, 4:12 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe	33 min
May 15, 4:24 PM EDT	Special Weather Statement	PHI	Berks	51 min
May 15, 4:26 PM EDT	Tornado Warning	PHI	Berks, Bucks, Lehigh, Montgomery, Northampton	19 min
May 15, 4:41 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery, Northampton	64 min
May 15, 5:12 PM EDT	Severe Thunderstorm Warning	PHI	Chester	63 min
May 15, 5:14 PM EDT	Areal Flood Advisory	PHI	Berks, Chester, Montgomery	2 hr
May 15, 5:22 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	38 min
May 15, 5:31 PM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Montgomery	3 hr
May 15, 5:35 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	4 hr
May 15, 5:38 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	67 min
May 15, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	52 min
May 15, 6:10 PM EDT	Areal Flood Advisory	PHI	Philadelphia	4 hr
May 15, 6:35 PM EDT	Severe Thunderstorm Warning	PHI	Chester	40 min
May 15, 6:58 PM EDT	Areal Flood Advisory	PHI	Chester	4 hr

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.