Alert archive / Pennsylvania / Special Weather Statements in 2020

Special Weather Statement, NWS Philadelphia/Mount Holly

August 7, 2020Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 7, 2020, 4:47 PM EDT for Chester County, Pennsylvania. It was in force for 28 min. 6 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
Aug 7, 2020, 4:47 PM EDT (20:47 UTC)
Expired
Aug 7, 2020, 5:15 PM EDT
In force
28 min
Issued by
NWS Philadelphia/Mount Holly

County Chester County, PA

The radar

The Dover AFB radar (KDOX), 130 km from the middle of the area, began a volume at 20:46 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
Aug 7, 5:02 PM EDTTSTM WND DMG2 Nnw Sadsburyville, PADOWN TREE IN WIRES ON OLD WILMINGTON ROAD AND OAK STREET. TIME ESTIMATED FROM RADAR.
Aug 7, 5:03 PM EDTTSTM WND DMGMount Vernon, PADOWNED TREE INTO WIRES ON PA 472 NEAR OXFORD. TIME ESTIMATED FROM RADAR.
Aug 7, 5:05 PM EDTTSTM WND DMGCochranville, PATREE BLOWN DOWN BLOCKING SOUTHBOUND LANE AT THE INTERSECTION OF LIMESTONE RD AND GAP NEWPORT PIKE. TIME ESTIMATED FROM RADAR.
Aug 7, 5:08 PM EDTTSTM WND DMG1 Ne Londonderry Twp, PASEVERAL TREES DOWN ALONG PORTIONS OF ROUTE 41. TIME ESTIMATED FROM RADAR.
Aug 7, 5:12 PM EDTTSTM WND DMG1 Ssw East Brandywine T, PASEVERAL TREES AND POLES DOWN JUST NORTH OF FISHERVILLE ROAD. TIME ESTIMATED FROM RADAR.
Aug 7, 5:25 PM EDTTSTM WND GST 522 E Londonderry Twp, PA52 MPH WIND GUST MEASURED AT WEST GROVE DEOS (DSCR) MESONET.

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, 8.8 hours before the alert went out and 164 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 2020-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 301 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 2020-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -37 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
301 J/kg
Mixed-layer CIN
-67 J/kg
Mixed-layer LCL
665 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
-37 m²/s²
0-3 km storm-relative helicity
18 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

799 
WWUS81 KPHI 072047
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
447 PM EDT Fri Aug 7 2020

PAZ101-102-072115-
Western Chester-Eastern Chester-
447 PM EDT Fri Aug 7 2020

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

At 445 PM EDT, a strong thunderstorm was located over Parkesburg, or
11 miles southeast of New Holland, moving east at 20 mph.

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

Heavy rainfall is also occurring with this storm...and may cause 
ponding on roadways and poor drainage areas. Do not drive your 
vehicle through flooded roadways.

Frequent lightning is occurring with this storm. Lightning can 
strike 15 miles away from a thunderstorm. If you see lightning or 
hear thunder seek a safe shelter inside a building or vehicle.

Locations impacted include...
Coatesville, Oxford, Parkesburg, West Grove, Honey Brook, Homeville,
Cochranville, Glenmoore, Mount Vernon, Kemblesville, Atglen, South
Coatesville, Modena and Thorndale.

This includes Pennsylvania Turnpike between mile markers 304 and 308.
 
LAT...LON 3983 7604 3983 7602 3985 7602 3987 7599
      3992 7600 3994 7598 3995 7600 4004 7593
      4011 7594 4013 7591 4014 7571 3973 7583
      3979 7605
TIME...MOT...LOC 2045Z 275DEG 16KT 3995 7597 

$$

Robertson

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 7, 5:15 PM EDTAreal Flood AdvisoryPHIHunterdon, Warren3 hr
Aug 7, 5:25 PM EDTAreal Flood AdvisoryPHIBurlington, Camden, Gloucester, Salem3 hr
Aug 7, 5:43 PM EDTFlash Flood WarningPHICamden, Gloucester4 hr
Aug 7, 5:57 PM EDTSevere Thunderstorm WarningPHIAtlantic, Burlington, Camden, Cumberland, Gloucester, Salem48 min
Aug 7, 6:00 PM EDTTornado WarningPHIGloucester, Salem30 min
Aug 7, 6:08 PM EDTAreal Flood AdvisoryPHICumberland, Gloucester, Salem3 hr
Aug 7, 6:16 PM EDTAreal Flood AdvisoryPHIMercer2 hr
Aug 7, 6:24 PM EDTSpecial Marine WarningPHI66 min
Aug 7, 6:39 PM EDTSevere Thunderstorm WarningPHIBurlington, Hunterdon, Mercer27 min
Aug 7, 6:41 PM EDTSevere Thunderstorm WarningPHIAtlantic, Camden, Cumberland, Gloucester, Salem49 min
Aug 7, 6:57 PM EDTSevere Thunderstorm WarningPHIAtlantic, Camden, Cumberland, Gloucester, Salem48 min
Aug 7, 7:24 PM EDTSpecial Marine WarningPHI66 min
Aug 7, 7:25 PM EDTFlash Flood WarningPHIAtlantic, Cape May, Cumberland, Gloucester4 hr
Aug 7, 7:28 PM EDTSevere Thunderstorm WarningPHIAtlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 1 more62 min
Aug 7, 6:49 AM EDTAreal Flood AdvisoryPHIBerks4 hr
Aug 7, 9:22 AM EDTAreal Flood AdvisoryPHIBucks3 hr
Aug 7, 10:34 AM EDTSevere Thunderstorm WarningPHICarbon, Lehigh56 min
Aug 7, 11:28 AM EDTSpecial Weather StatementPHICarbon, Lehigh47 min
Aug 7, 2:34 PM EDTAreal Flood AdvisoryPHIBerks4 hr
Aug 7, 3:46 PM EDTAreal Flood AdvisoryPHICarbon, Lehigh, Northampton4 hr
Aug 7, 4:10 PM EDTFlash Flood WarningPHIBerks2 hr
Aug 7, 4:20 PM EDTAreal Flood AdvisoryPHIChester, Montgomery4 hr
Aug 7, 4:32 PM EDTFlash Flood WarningPHIChester3 hr
Aug 7, 5:00 PM EDTSevere Thunderstorm WarningPHIChester60 min
Aug 7, 5:03 PM EDTFlash Flood WarningPHIChester, Delaware5 hr
Aug 7, 5:38 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia52 min
Aug 7, 5:49 PM EDTTornado WarningPHIChester, Delaware26 min
Aug 7, 7:10 PM EDTRiver Flood WarningPHIDelaware7 hr
Aug 7, 7:17 PM EDTAreal Flood WarningPHIBucks, Montgomery3 hr
Aug 7, 6:12 PM EDTSevere Thunderstorm WarningPHIKent, New Castle63 min
Aug 7, 6:43 PM EDTAreal Flood AdvisoryPHIKent, New Castle4 hr
Aug 7, 7:04 PM EDTSevere Thunderstorm WarningPHIKent, New Castle41 min
Aug 7, 7:21 PM EDTFlash Flood WarningPHIKent, New Castle5 hr
Aug 7, 7:28 PM EDTRiver Flood WarningPHINew Castle2 hr
Aug 7, 7:36 PM EDTSpecial Weather StatementPHIKent39 min
Aug 7, 4:41 PM EDTAreal Flood AdvisoryPHICecil3 hr
Aug 7, 7:44 PM EDTFlash Flood WarningPHICaroline, Kent, Queen Anne's4 hr

Nearby

Special Weather Statements in Pennsylvania, 2020Every special weather statement in 2020

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.