Alert archive / Pennsylvania / Flash Flood Warnings in 2020

Flash Flood Warning 47, NWS Philadelphia/Mount Holly

August 7, 2020Chester County, Delaware County, Pennsylvania; New Castle County, Delaware; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 7, 2020, 5:03 PM EDT for Chester County, Delaware County, Pennsylvania; New Castle County, Delaware; Cecil County, Maryland. It was in force for 5 hr. 36 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, 5:03 PM EDT (21:03 UTC)
Expired: Aug 7, 2020, 9:51 PM EDT
In force: 5 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties New Castle County, DE, Cecil County, MD, Chester County, PA, Delaware County, PA

The radar

The Dover AFB radar (KDOX), 105 km from the middle of the area, began a volume at 21:04 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

Time	Report	Where	Remark
Aug 7, 5:45 PM EDT	FLASH FLOOD	Hockessin, DE	SIGNIFICANT FLOODING ACROSS LANCASTER PIKE IN HOCKESSIN WITH AT LEAST ONE CAR STUCK IN THE FLOOD WATERS.
Aug 7, 5:52 PM EDT	FLASH FLOOD	1 S Kennett Square, PA	ONE VEHICLE STUCK IN RISING WATER AT SOUTH ST. AND HARVEY CIRCLE IN KENNETT SQUARE. TIME ESTIMATED FROM DISPATCH.
Aug 7, 5:56 PM EDT	FLOOD	2 S Kennett Square, PA	STREAM WAS REPORTED BLOCKED AND CREATING A LAKE ON THE ROADWAY AT THE INTERSECTION OF BUCKTOE RD. AND CHANDLER MILL RD.
Aug 7, 5:58 PM EDT	FLASH FLOOD	1 Ne Toughkenamon, PA	ROADWAY FLOODED AT BANCROFT RD AND CRESTVIEW DR IN NEW GARDEN TOWNSHIP. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:00 PM EDT	HEAVY RAIN 3.37	2 N Avondale, PA	MESONET STATION AVOP1 2.4 N AVONDALE.
Aug 7, 6:03 PM EDT	FLASH FLOOD	1 Ese Trainer, PA	WATER RESCUE REPORTED.
Aug 7, 6:03 PM EDT	FLASH FLOOD	1 S Kennett Square, PA	WATER RESCUE AT THE INTERSECTION OF SOUTH STREET AND HARVEY CIRCLE.
Aug 7, 6:10 PM EDT	FLASH FLOOD	1 Nw Ashland, DE	A HOME IN YORKLYN WAS TAKING ON WATER.
Aug 7, 6:10 PM EDT	FLASH FLOOD	Aston Twp., PA	WATER RESCUE AT WEIR RD AND PENNELL RD. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:11 PM EDT	FLASH FLOOD	Aston Twp., PA	WATER RESCUE REPORTED ON RAYMOND AVENUE IN ASHTON TOWNSHIP.
Aug 7, 6:12 PM EDT	FLASH FLOOD	Green Ridge, PA	ROAD CLOSURE AT E DUTTON MILL RD AND CHESTER CREEK RD. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:15 PM EDT	FLASH FLOOD	2 N Avondale, PA	WATER RESCUE AT THE INTERSECTION OF MCCUE ROAD AND WOODVIEW ROAD.
Aug 7, 6:15 PM EDT	FLASH FLOOD	Upper Chichester Twp, PA	PICTURE SHOWS DEEP WATER CLOSING A ROAD IN UPPER CHICHESTER TOWNSHIP. TIME ESTIMATED FROM RADAR AND NEARBY REPORTS.
Aug 7, 6:16 PM EDT	FLASH FLOOD	1 Wnw Springfield Twp, PA	CORRECTS PREVIOUS FLASH FLOOD REPORT FROM 1 WNW SPRINGFIELD TWP. WATER RESCUE REPORTED ON OLD MARPLE RD MARPLE TOWNSHIP. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:16 PM EDT	FLASH FLOOD	1 Wnw Springfield Twp, PA	WATER RESCUE REPORTED ON OLD MARPLE RD MARPLE TOWNSHIP. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:17 PM EDT	FLASH FLOOD	Aston Twp., PA	WATER RESCUE REPORTED AT CONCORD RD IN ASHTON TOWNSHIP.
Aug 7, 6:21 PM EDT	FLASH FLOOD	3 S Kennett Square, PA	CREEK FLOODING AT KAOLIN RD AND CALDWELL LN. ROAD CLOSED. TIMES ESTIMATED FROM DISPATCH.
Aug 7, 6:25 PM EDT	FLASH FLOOD	1 Ese Landenberg, PA	CORRECTS PREVIOUS FLASH FLOOD REPORT FROM 1 ESE LANDENBERG. BROAD RUN RD AT NEWARK RD ROAD CLOSED DUE TO HIGH WATER. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:25 PM EDT	FLASH FLOOD	1 Ese Landenberg, PA	BROAD RUN RD AT NEWARK RD ROAD CLOSED DUE TO HIGH WATER. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:26 PM EDT	FLASH FLOOD	1 Ene Concordville, PA	WATER RESCUE AT BALTIMORE PIKE AND CHEYNEY RD. TIME ESTIMATED FROM DISPATCH.
Aug 7, 6:30 PM EDT	FLASH FLOOD	1 Ssw Kennett Square, PA	WATER RESCUE AT W HILLENDALE RD AND CHANDLER MILL RD. TIME BASED OFF OF DISPATCH.
Aug 7, 6:30 PM EDT	HEAVY RAIN 4.06	Winterthur, DE	GREENVILLE DEOS STATION. 4.06 INCHES OF RAIN OCCURRED IN AN HOUR WITH MOST OF THAT FALLING IN A 30 MINUTE PERIOD.
Aug 7, 6:40 PM EDT	FLASH FLOOD	1 Ene Ashbourne Hills, DE	INTERSTATE 95 SOUTHBOUND IS CLOSED AT THE PENNSYLVANIA LINE DUE TO FLOODING.
Aug 7, 6:40 PM EDT	FLASH FLOOD	1 Ssw Boothwyn, PA	PICTURE ON SOCIAL MEDIA SHOWS FLOODING AT A LOCAL BUSINESS NEAR THE WEST BRANCH NAAMAN CREEK. TIME ESTIMATED FROM RADAR AND NEARBY REPORTS.
Aug 7, 6:40 PM EDT	HEAVY RAIN 3.51	Aston Twp., PA	3.51 INCHES OF RAIN IN 50 MINUTES ENDING AT 6:40 PM.
Aug 7, 6:43 PM EDT	HEAVY RAIN 2.93	1 Se New London Twp., PA	MESONET STATION AU860 NEW LONDON.
Aug 7, 6:45 PM EDT	HEAVY RAIN 2.58	Boothwyn, PA	MESONET STATION FW6806 UPPER CHICHESTER.
Aug 7, 6:45 PM EDT	HEAVY RAIN 3.26	1 Ne Talleyville, DE	MESONET STATION 3035D TALLEYVILLE.
Aug 7, 6:47 PM EDT	HEAVY RAIN 2.42	1 Nnw Lima, PA	MESONET STATION FW6794 MEDIA.
Aug 7, 6:47 PM EDT	HEAVY RAIN 3.21	1 Sse Birmingham Twp, PA	MESONET STATION CW4403 CHADDS FORD.
Aug 7, 6:47 PM EDT	HEAVY RAIN 3.21	2 Ssw Lincoln Universit, PA	MESONET STATION AV071 OXFORD.
Aug 7, 6:48 PM EDT	HEAVY RAIN 2.25	2 Ssw Cheyney, PA	MESONET STATION EW8556 THORNTON.
Aug 7, 6:49 PM EDT	HEAVY RAIN 2.45	1 Ene Westwood Manor, DE	MESONET STATION WILMG WILMINGTON (ST. EDMONS).
Aug 7, 6:50 PM EDT	HEAVY RAIN 2.11	1 S Lima, PA	MESONET STATION FW3096 MEDIA.
Aug 7, 7:00 PM EDT	FLASH FLOOD	Middletown Twp., PA	ROUTE 1 CLOSED IN SEVERAL LOCATIONS DUE TO FLOODING.
Aug 7, 9:45 PM EDT	FLASH FLOOD	Elkton, MD	WATER RESCUE ON DELAWARE AVE NEAR MEADOW PARK. ROAD WAS CLOSED DUE TO FLOODING. TIME ESTIMATED FROM RADAR.

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, 9.1 hours before the alert went out and 174 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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.

210 
WGUS51 KPHI 072103
FFWPHI
DEC003-MDC015-PAC029-045-080300-
/O.NEW.KPHI.FF.W.0047.200807T2103Z-200808T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
503 PM EDT Fri Aug 7 2020

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Northern New Castle County in northern Delaware...
  Cecil County in northeastern Maryland...
  Southern Chester County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 1100 PM EDT.

* At 500 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain moving into the warned area. Flash flooding is expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar indicated.

  IMPACT...Flooding of small creeks and streams, urban areas, 
           highways, streets and underpasses as well as other 
           poor drainage and low lying areas.

* Some locations that could experience flooding include...
  Wilmington, Newark, Elkton, Calvert, Chester, Yeadon, Folcroft,
  Swarthmore, Elsmere, Kennett Square, New Castle, Oxford, North
  East, West Grove, Rising Sun, East Lansdowne, Delaware City,
  Charlestown, Newport and Arden.

Additional rainfall amounts of 1 to 3 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets, and underpasses
as well as other poor drainage areas and low lying spots.

&&

LAT...LON 3972 7623 3973 7610 3987 7599 3991 7599
      3989 7557 4006 7536 3996 7525 3988 7526
      3987 7521 3984 7536 3977 7546 3971 7549
      3972 7552 3962 7561 3959 7561 3960 7558
      3953 7557 3954 7570 3955 7608

FLASH FLOOD...RADAR INDICATED

$$

Iovino

2 follow-up statements

180 
WGUS71 KPHI 080008
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
808 PM EDT Fri Aug 7 2020

MDC015-080014-
/O.CAN.KPHI.FF.W.0047.000000T0000Z-200808T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Cecil MD-
808 PM EDT Fri Aug 7 2020

...THE FLASH FLOOD WARNING FOR CECIL COUNTY IS CANCELLED...

Flooding is no longer expected to pose a threat. Please continue to
heed any remaining road closures.

LAT...LON 3976 7606 3987 7599 3991 7599 3989 7557
      4006 7536 3996 7525 3988 7526 3987 7521
      3984 7536 3977 7546 3971 7549 3972 7552
      3962 7561 3959 7561 3960 7558 3953 7557
      3954 7578 3972 7579 3972 7613

$$

DEC003-PAC029-045-080300-
/O.CON.KPHI.FF.W.0047.000000T0000Z-200808T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Chester PA-Delaware PA-
808 PM EDT Fri Aug 7 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1100 PM EDT FOR
NORTHERN NEW CASTLE...SOUTHERN CHESTER AND DELAWARE COUNTIES...

At 804 PM EDT, flooding continued as a result of today's heavy 
rainfall.

Flooding was occurring along parts of the White Clay Creek, Red Clay 
Creek, Brandywine Creek, Chester Creek and Ridley Creek.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar indicated.

IMPACT...Flooding of small creeks and streams, urban areas, 
         highways, streets and underpasses as well as other 
         poor drainage and low lying areas.

Some locations are experiencing flooding include...Wilmington, 
Newark, Chester, Yeadon, Folcroft, Swarthmore, Elsmere, Kennett 
Square, New Castle, Oxford, West Grove, East Lansdowne, Delaware 
City, Newport, Arden, Glen Roy, Darby Township, Stanton, Glasgow and 
Talleyville.

Little additional rainfall is expected.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Excessive runoff from heavy rainfall will continue to cause flooding 
of small creeks and streams, urban areas, highways, streets, and 
underpasses as well as other poor drainage areas and low lying spots.

&&

LAT...LON 3976 7606 3987 7599 3991 7599 3989 7557
      4006 7536 3996 7525 3988 7526 3987 7521
      3984 7536 3977 7546 3971 7549 3972 7552
      3962 7561 3959 7561 3960 7558 3953 7557
      3954 7578 3972 7579 3972 7613

FLASH FLOOD...RADAR INDICATED

$$

Iovino

823 
WGUS71 KPHI 080151
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
951 PM EDT Fri Aug 7 2020

DEC003-PAC029-045-080159-
/O.CAN.KPHI.FF.W.0047.000000T0000Z-200808T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Chester PA-Delaware PA-
951 PM EDT Fri Aug 7 2020

...THE FLASH FLOOD WARNING FOR NORTHERN NEW CASTLE...SOUTHERN CHESTER
AND DELAWARE COUNTIES IS CANCELLED...

Flood waters are receding. Additional flooding is no longer expected 
to pose a threat. Please continue to heed any remaining road 
closures.

Flood Warnings remain in effect for the White Clay Creek, Red Clay 
Creek, Chester Creek and Ridley Creek.

LAT...LON 3976 7606 3987 7599 3991 7599 3989 7557
      4006 7536 3996 7525 3988 7526 3987 7521
      3984 7536 3977 7546 3971 7549 3972 7552
      3962 7561 3959 7561 3960 7558 3953 7557
      3954 7578 3972 7579 3972 7613

$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 7, 6:49 AM EDT	Areal Flood Advisory	PHI	Berks	4 hr
Aug 7, 9:22 AM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Aug 7, 10:34 AM EDT	Severe Thunderstorm Warning	PHI	Carbon, Lehigh	56 min
Aug 7, 11:28 AM EDT	Special Weather Statement	PHI	Carbon, Lehigh	47 min
Aug 7, 2:34 PM EDT	Areal Flood Advisory	PHI	Berks	4 hr
Aug 7, 3:46 PM EDT	Areal Flood Advisory	PHI	Carbon, Lehigh, Northampton	4 hr
Aug 7, 4:10 PM EDT	Flash Flood Warning	PHI	Berks	2 hr
Aug 7, 4:20 PM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	4 hr
Aug 7, 4:32 PM EDT	Flash Flood Warning	PHI	Chester	3 hr
Aug 7, 4:47 PM EDT	Special Weather Statement	PHI	Chester	28 min
Aug 7, 5:00 PM EDT	Severe Thunderstorm Warning	PHI	Chester	60 min
Aug 7, 5:15 PM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Aug 7, 5:25 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	3 hr
Aug 7, 5:38 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	52 min
Aug 7, 5:43 PM EDT	Flash Flood Warning	PHI	Montgomery, Philadelphia	4 hr
Aug 7, 5:49 PM EDT	Tornado Warning	PHI	Chester, Delaware	26 min
Aug 7, 5:57 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	48 min
Aug 7, 6:00 PM EDT	Tornado Warning	PHI	Delaware	30 min
Aug 7, 6:39 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	27 min
Aug 7, 7:10 PM EDT	River Flood Warning	PHI	Delaware	7 hr
Aug 7, 7:17 PM EDT	Areal Flood Warning	PHI	Bucks, Montgomery	3 hr
Aug 7, 6:12 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	63 min
Aug 7, 6:43 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	4 hr
Aug 7, 7:04 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	41 min
Aug 7, 7:21 PM EDT	Flash Flood Warning	PHI	Kent, New Castle	5 hr
Aug 7, 7:28 PM EDT	River Flood Warning	PHI	New Castle	2 hr
Aug 7, 7:36 PM EDT	Special Weather Statement	PHI	Kent	39 min
Aug 7, 4:41 PM EDT	Areal Flood Advisory	PHI	Cecil	3 hr
Aug 7, 7:44 PM EDT	Flash Flood Warning	PHI	Caroline, Kent, Queen Anne's	4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2020 Flash Flood Warnings in Delaware, 2020 Flash Flood Warnings in Maryland, 2020 Every flash flood warning 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.