Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

April 21, 2021Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Apr 21, 2021, 12:54 PM EDT for Delaware County, Pennsylvania. It was in force for 36 min. 2 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 21, 2021, 12:54 PM EDT (16:54 UTC)
Expired
Apr 21, 2021, 1:30 PM EDT
In force
36 min
Issued by
NWS Philadelphia/Mount Holly

County Delaware County, PA

The radar

The Philadelphia radar (KDIX), 103 km from the middle of the area, began a volume at 16:56 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

TimeReportWhereRemark
Apr 21, 12:55 PM EDTHAIL 0.25Kennett Square, PA
Apr 21, 1:15 PM EDTHAIL 0.251 Ne Brookfield, PA

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, 4.9 hours before the alert went out and 181 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 2021-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 8 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2021-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 128 square meters per square second.19395878Sfc1 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
8 J/kg
Mixed-layer CIN
-277 J/kg
Mixed-layer LCL
1577 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
128 m²/s²
0-3 km storm-relative helicity
109 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

243 
WWUS81 KPHI 211654
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
1254 PM EDT Wed Apr 21 2021

DEZ001-NJZ016-PAZ070-102-104-211730-
New Castle-Salem-Eastern Montgomery-Delaware-Eastern Chester-
1254 PM EDT Wed Apr 21 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHERN NEW CASTLE...
NORTHWESTERN SALEM...SOUTH CENTRAL MONTGOMERY...SOUTHEASTERN CHESTER
AND DELAWARE COUNTIES...

At 1253 PM EDT, radar indicated strong thunderstorms were located
along a line extending from Kennett Square to Elkton. Movement was
northeast at 55 mph.

Wind gusts up to 40 mph and half inch hail are possible with these
storms.

Locations impacted include...
Wilmington, Newark, West Chester, Norristown, Chester, West Norriton,
East Norriton, Pennsville, Westtown, Carneys Point, Elsmere, Kennett
Square, New Castle, Penns Grove, Newport, Arden, Stanton, Cheyney,
Glasgow and Talleyville.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 328 and 332.
 Interstate 95 in Pennsylvania between mile markers 0 and 3.
 Interstate 95 in Delaware between mile markers 1 and 23.
 Interstate 76 in Pennsylvania between mile markers 327 and 331.
 Interstate 295 in New Jersey between mile markers 0 and 5.
 Interstate 476 in Pennsylvania near mile marker 5, and between mile
markers 10 and 17.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3988 7579 4015 7529 3979 7541 3978 7544
      3978 7541 3970 7544 3955 7578 3972 7579
      3972 7584
TIME...MOT...LOC 1653Z 230DEG 47KT 3986 7572 3961 7581 

$$

JEO

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 20, 8:48 PM EDTFreeze WatchPHIHunterdon, Morris, Somerset, Sussex, Warren7 hr
Apr 21, 3:26 AM EDTFreeze WarningPHIHunterdon, Morris, Somerset, Sussex, Warren30 hr
Apr 21, 12:25 PM EDTSevere Thunderstorm WarningPHIWarren50 min
Apr 21, 12:51 PM EDTSevere Thunderstorm WarningPHISussex, Warren21 min
Apr 21, 12:55 PM EDTSevere Thunderstorm WarningPHIHunterdon, Warren27 min
Apr 21, 1:10 PM EDTSevere Thunderstorm WarningPHIBurlington, Camden, Gloucester, Mercer, Salem50 min
Apr 21, 1:17 PM EDTSpecial Weather StatementPHIHunterdon, Morris, Somerset, Sussex58 min
Apr 21, 1:28 PM EDTSevere Thunderstorm WarningPHIAtlantic, Burlington, Camden, Gloucester36 min
Apr 21, 1:30 PM EDTSpecial Marine WarningPHI60 min
Apr 21, 1:43 PM EDTSevere Thunderstorm WarningPHIHunterdon, Middlesex, Morris, Somerset33 min
Apr 21, 1:58 PM EDTSpecial Weather StatementPHIBurlington, Camden, Monmouth, Ocean62 min
Apr 21, 2:02 PM EDTSevere Thunderstorm WarningPHIBurlington, Camden, Monmouth, Ocean43 min
Apr 21, 2:03 PM EDTSpecial Weather StatementPHICumberland27 min
Apr 21, 2:17 PM EDTSevere Thunderstorm WarningPHIAtlantic, Cumberland, Gloucester, Salem43 min
Apr 21, 2:28 PM EDTSpecial Weather StatementPHIMiddlesex, Monmouth47 min
Apr 21, 2:30 PM EDTSpecial Marine WarningPHI60 min
Apr 21, 2:38 PM EDTSevere Thunderstorm WarningPHIMonmouth, Ocean37 min
Apr 21, 2:40 PM EDTSpecial Marine WarningPHI55 min
Apr 21, 2:43 PM EDTSpecial Weather StatementPHICape May32 min
Apr 21, 2:50 PM EDTSevere Thunderstorm WarningPHIAtlantic, Burlington, Ocean40 min
Apr 21, 3:02 PM EDTSevere Thunderstorm WarningPHIAtlantic28 min
Apr 21, 3:07 PM EDTSpecial Marine WarningPHI53 min
Apr 21, 12:03 PM EDTSpecial Weather StatementPHIChester, Lehigh42 min
Apr 21, 12:17 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery, Northampton43 min
Apr 21, 1:23 PM EDTSevere Thunderstorm WarningPHIKent37 min
Apr 21, 2:09 PM EDTSpecial Weather StatementPHISussex36 min
Apr 21, 2:18 PM EDTSevere Thunderstorm WarningPHIKent, Sussex42 min
Apr 21, 2:47 PM EDTSevere Thunderstorm WarningPHISussex16 min
Apr 21, 12:50 PM EDTSevere Thunderstorm WarningPHICaroline, Kent, Queen Anne's, Talbot40 min

Nearby

Special Weather Statements in Pennsylvania, 2021Every special weather statement 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.