Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

April 10, 2021Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Apr 10, 2021, 2:34 AM EDT for Chester County, Pennsylvania. It was in force for 41 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
Apr 10, 2021, 2:34 AM EDT (06:34 UTC)
Expired
Apr 10, 2021, 3:15 AM EDT
In force
41 min
Issued by
NWS Philadelphia/Mount Holly

County Chester County, PA

The radar

The Dover AFB radar (KDOX), 113 km from the middle of the area, began a volume at 06:37 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 00:00Z, 6.6 hours before the alert went out and 172 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 00:00Z on 2021-04-10Temperature 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 00:00Z on 2021-04-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 161 square meters per square second.193958Sfc1 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
537 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
161 m²/s²
0-3 km storm-relative helicity
238 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

486 
WWUS81 KPHI 100634
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
234 AM EDT Sat Apr 10 2021

DEZ001-PAZ102-100715-
New Castle-Eastern Chester-
234 AM EDT Sat Apr 10 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN NEW CASTLE AND
SOUTH CENTRAL CHESTER COUNTIES...

At 233 AM EDT, a strong thunderstorm was located over Ladenberg, or 7
miles north of Newark, moving east at 10 mph.

Wind gusts up to 30 mph are possible with this storm.

Locations impacted include...
Wilmington, Newark, Elsmere, Kennett Square, West Grove, Newport,
Greenville, Stanton, North Star, Ladenberg, Pike Creek, Kemblesville,
Hockessin, Ashland, Wilmington Manor, Avondale, Toughkenamon and
Brookside.

This includes Interstate 95 in Delaware between mile markers 8 and
16.
 
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3984 7590 3985 7586 3986 7585 3996 7564
      3986 7559 3986 7560 3984 7559 3984 7558
      3971 7551 3966 7579 3972 7579 3972 7587
      3981 7591
TIME...MOT...LOC 0633Z 249DEG 9KT 3978 7579 

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 10, 3:22 AM EDTAreal Flood AdvisoryPHIBurlington, Camden, Gloucester, Salem2 hr
Apr 10, 3:44 AM EDTSpecial Weather StatementPHIGloucester46 min
Apr 10, 4:42 AM EDTSpecial Weather StatementPHIGloucester48 min
Apr 10, 4:00 PM EDTSmall Craft AdvisoryPHI3 days
Apr 10, 1:19 AM EDTSpecial Weather StatementPHIChester56 min
Apr 10, 2:35 AM EDTSpecial Weather StatementPHIDelaware40 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.