Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

August 13, 2021Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 13, 2021, 5:31 PM EDT for Chester County, Pennsylvania. It was in force for 44 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
Aug 13, 2021, 5:31 PM EDT (21:31 UTC)
Expired
Aug 13, 2021, 6:15 PM EDT
In force
44 min
Issued by
NWS Philadelphia/Mount Holly
Hail
0.00 in
Wind
40

County Chester County, PA

The radar

The Dover AFB radar (KDOX), 119 km from the middle of the area, began a volume at 21:33 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, 9.5 hours before the alert went out and 152 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 2021-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 313 joules per kilogram.LCLLFCEL10008507005003002001001 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 2021-08-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -11 square meters per square second.1939Sfc1 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
313 J/kg
Mixed-layer CIN
-199 J/kg
Mixed-layer LCL
1675 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
-11 m²/s²
0-3 km storm-relative helicity
58 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

531 
WWUS81 KPHI 132131
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
531 PM EDT Fri Aug 13 2021
 
PAZ101-102-132215-
Western Chester PA-Eastern Chester PA-
531 PM EDT Fri Aug 13 2021

...A strong thunderstorm will impact portions of southwestern Chester
County through 615 PM EDT...

At 530 PM EDT, Doppler radar was tracking a strong thunderstorm near
Delta, or 14 miles south of Willow Street, moving east at 35 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

A Severe Thunderstorm Watch remains in effect until 800 PM EDT for
southeastern Pennsylvania.

&&

LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
      3981 7603 3983 7604 3983 7602 3987 7601
      3987 7599 3991 7599 3994 7577 3972 7578
      3972 7613
TIME...MOT...LOC 2130Z 269DEG 29KT 3977 7632 

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

$$

PO

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 12, 11:49 PM EDTSpecial Weather StatementPHIHunterdon, Middlesex, Morris, Somerset, Sussex, Warren56 min
Aug 13, 7:32 PM EDTSpecial Marine WarningPHI88 min
Aug 12, 10:27 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon48 min
Aug 12, 11:20 PM EDTSpecial Weather StatementPHICarbon, Lehigh, Northampton40 min
Aug 13, 3:21 PM EDTSpecial Weather StatementPHISussex24 min
Aug 13, 6:04 PM EDTSpecial Weather StatementPHISussex26 min
Aug 13, 6:45 PM EDTSevere Thunderstorm WarningPHIKent30 min
Aug 13, 6:47 PM EDTSpecial Weather StatementPHISussex43 min
Aug 13, 6:53 PM EDTSevere Thunderstorm WarningPHISussex37 min
Aug 13, 7:12 PM EDTSevere Thunderstorm WarningPHIKent, Sussex33 min
Aug 13, 7:30 PM EDTSpecial Weather StatementPHISussex45 min
Aug 13, 7:43 PM EDTSevere Thunderstorm WarningPHIKent, Sussex47 min
Aug 13, 7:57 PM EDTAreal Flood AdvisoryPHIKent, Sussex93 min
Aug 13, 6:02 PM EDTSpecial Weather StatementPHIKent, Queen Anne's58 min
Aug 13, 6:29 PM EDTSpecial Weather StatementPHICaroline31 min
Aug 13, 6:29 PM EDTSevere Thunderstorm WarningPHIQueen Anne's, Talbot25 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.