Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 313, NWS Philadelphia/Mount Holly

October 16, 2021Chester County, Pennsylvania; Salem County, New Jersey; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Oct 16, 2021, 3:31 PM EDT for Chester County, Pennsylvania; Salem County, New Jersey; New Castle County, Delaware. It was in force for 18 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
Oct 16, 2021, 3:31 PM EDT (19:31 UTC)
Expired
Oct 16, 2021, 3:49 PM EDT
In force
18 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties New Castle County, DE, Salem County, NJ, Chester County, PA

The radar

The Dover AFB radar (KDOX), 101 km from the middle of the area, began a volume at 19:34 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 nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 7.5 hours before the alert went out and 170 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2021-10-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2021-10-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 141 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
1259 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
141 m²/s²
0-3 km storm-relative helicity
192 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

408 
WUUS51 KPHI 161931
SVRPHI
DEC003-NJC033-PAC029-162000-
/O.NEW.KPHI.SV.W.0313.211016T1931Z-211016T2000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
331 PM EDT Sat Oct 16 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northern New Castle County in northern Delaware...
  West central Salem County in southern New Jersey...
  Southern Chester County in southeastern Pennsylvania...

* Until 400 PM EDT.

* At 331 PM EDT, a severe thunderstorm was located over Barksdale, or
  over Newark, moving east at 35 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Wilmington, Newark, Pennsville, Carneys Point, Elsmere, New Castle,
  Newport, Greenville, Stanton, North Star, Glasgow, Bear,
  Talleyville, Delaware Memorial Bridge, Wilmington Manor, Pike
  Creek, Hockessin, Ashland, Bellefonte and Edgemoor.

This includes the following highways...
 Interstate 95 in Delaware between mile markers 0 and 18.
 Interstate 295 in New Jersey between mile markers 0 and 2.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3982 7565 3983 7552 3961 7544 3957 7578
      3962 7579 3972 7579 3972 7585
TIME...MOT...LOC 1931Z 249DEG 29KT 3966 7580 

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

$$

Fitzsimmons
1 follow-up statement
258 
WWUS51 KPHI 161949
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
349 PM EDT Sat Oct 16 2021

DEC003-NJC033-PAC029-161958-
/O.CAN.KPHI.SV.W.0313.000000T0000Z-211016T2000Z/
New Castle DE-Salem NJ-Chester PA-
349 PM EDT Sat Oct 16 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN NEW CASTLE...WEST
CENTRAL SALEM AND SOUTHERN CHESTER COUNTIES IS CANCELLED...
                
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 has been cancelled.  However gusty winds are 
still likely with this thunderstorm with gusts up to 45 mph 
possible. 

LAT...LON 3982 7565 3983 7552 3961 7544 3957 7578
      3962 7579 3972 7579 3972 7585
TIME...MOT...LOC 1947Z 249DEG 29KT 3971 7563 

$$

Fitzsimmons

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 16, 1:39 PM EDTSpecial Weather StatementPHIBerks51 min
Oct 16, 2:32 PM EDTSpecial Weather StatementPHIBerks, Lehigh58 min
Oct 16, 2:44 PM EDTSpecial Weather StatementPHIChester61 min
Oct 16, 3:41 PM EDTSpecial Weather StatementPHIBucks49 min
Oct 16, 4:02 PM EDTSevere Thunderstorm WarningPHIBucks43 min
Oct 16, 4:18 PM EDTSpecial Weather StatementPHIDelaware, Montgomery, Philadelphia57 min
Oct 16, 10:35 AM EDTCoastal Flood StatementPHIOcean2 hr
Oct 16, 3:22 PM EDTSpecial Marine WarningPHI113 min
Oct 16, 5:10 PM EDTSpecial Marine WarningPHI95 min
Oct 16, 5:29 PM EDTSpecial Marine WarningPHI91 min
Oct 16, 6:09 PM EDTSpecial Marine WarningPHI66 min
Oct 16, 6:52 PM EDTCoastal Flood StatementPHIOcean4 hr
Oct 16, 3:40 PM EDTSpecial Weather StatementPHINew Castle50 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2021Severe Thunderstorm Warnings in New Jersey, 2021Severe Thunderstorm Warnings in Delaware, 2021Every severe thunderstorm warning in 2021

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.