Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

July 25, 2021Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Jul 25, 2021, 3:43 PM EDT for Chester County, Pennsylvania. It was in force for 47 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
Jul 25, 2021, 3:43 PM EDT (19:43 UTC)
Expired
Jul 25, 2021, 4:30 PM EDT
In force
47 min
Issued by
NWS Philadelphia/Mount Holly

County Chester County, PA

The radar

The Dover AFB radar (KDOX), 119 km from the middle of the area, began a volume at 19:42 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, 7.7 hours before the alert went out and 151 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 2021-07-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 375 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 2021-07-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 104 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
375 J/kg
Mixed-layer CIN
-92 J/kg
Mixed-layer LCL
780 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
104 m²/s²
0-3 km storm-relative helicity
68 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted.

576 
WWUS81 KPHI 251943
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
343 PM EDT Sun Jul 25 2021

PAZ101-102-252030-
Western Chester-Eastern Chester-
343 PM EDT Sun Jul 25 2021

...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN CHESTER COUNTY...

At 342 PM EDT, a strong thunderstorm was located near Quarryville in 
Lancaster County, moving southeast at 20 mph.

Wind gusts up to 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Oxford, West Grove, Homeville, Glen Roy, Mount Vernon, Cochranville,
Kemblesville, Avondale and Toughkenamon.

If outdoors, consider seeking shelter inside a building.

LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
      3981 7603 3983 7604 3983 7602 3987 7601
      3987 7599 3992 7600 3987 7572 3972 7583
      3972 7613
TIME...MOT...LOC 1942Z 297DEG 18KT 3985 7611 

$$

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 25, 7:53 PM EDTAreal Flood AdvisoryPHIChester5 hr

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.