Alert archive / Pennsylvania / Flash Flood Warnings in 2020
Flash Flood Warning 32, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 4, 2020, 7:28 AM EDT for New Castle County, Delaware; Chester County, Delaware County, Montgomery County, Pennsylvania; Gloucester County, Salem County, New Jersey. It was in force for 3 hr. 12 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 4, 2020, 7:28 AM EDT (11:28 UTC)
- Expired
- Aug 4, 2020, 10:30 AM EDT
- In force
- 3 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Flood severity
- None
Counties New Castle County, DE, Gloucester County, NJ, Salem County, NJ, Chester County, PA, Delaware County, PA, Montgomery County, PA
The radar
The Philadelphia radar (KDIX), 89 km from the middle of the area, began a volume at 11:31 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 4, 7:30 AM EDT | HEAVY RAIN 2.08 | 1 W Easttown Twp, PA | COCORAHS STATION PA-CH-42 BERWYN. |
| Aug 4, 7:40 AM EDT | FLOOD | 1 Ne Claymont, DE | FLOODING ON EXIT 5 RAMP OF INTERSTATE 495 TO NAAMANS ROAD. TIME BASED ON DISPATCH REPORT. |
| Aug 4, 8:00 AM EDT | HEAVY RAIN 2.11 | 2 W Schwenksville, PA | COCORAHS STATION PA-MT-96 SCHWENKSVILLE 1.6 WSW. |
| Aug 4, 8:00 AM EDT | HEAVY RAIN 3.43 | 1 N Collegeville, PA | COCORAHS STATION PA-MT-91 COLLEGEVILLE. |
| Aug 4, 8:00 AM EDT | HEAVY RAIN 3.43 | Haverford, PA | COCORAHS STATION PA-MT-48 ARDMORE 0.5 NW. |
| Aug 4, 8:30 AM EDT | FLASH FLOOD | Norristown, PA | MULTIPLE WATER RESCUES IN NORRISTOWN AREA. |
| Aug 4, 8:30 AM EDT | FLASH FLOOD | Upper Merion, PA | MULTIPLE WATER RESCUES IN UPPER MERION. |
| Aug 4, 8:33 AM EDT | HEAVY RAIN 2.74 | 1 Nne Skippack, PA | COCORAHS STATION PA-MT-51 HARLEYSVILLE 2.9 S. |
| Aug 4, 8:40 AM EDT | FLOOD | 1 Ssw Collegeville, PA | PARTS OF ROUTE 113 AND ROUTE 29 FLOODED. |
| Aug 4, 9:38 AM EDT | FLASH FLOOD | 1 Ne Wayne, PA | LIVE VIDEO SHOWING FLASH FLOODING IN RADNOR TWP. |
| Aug 4, 10:30 AM EDT | FLASH FLOOD | 1 Ne Lawrence Park, PA | DARBY CREEK ROAD CLOSED NEAR LAWRENCE ROAD FROM FLASH FLOODING. TIME BASED ON DISPATCH REPORT. |
| Aug 4, 10:37 AM EDT | FLASH FLOOD | 1 N Trout Lake, PA | FLASH FLOODING CLOSED BRYN MAWR AVENUE NEAR MILL ROAD. TIME BASED ON DISPATCH REPORT. |
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 00:00Z, 11.5 hours before the alert went out and 207 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.
- Mixed-layer CAPE
- 89 J/kg
- Mixed-layer CIN
- -54 J/kg
- Mixed-layer LCL
- 889 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 65 m²/s²
- 0-3 km storm-relative helicity
- 140 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
116
WGUS51 KPHI 041128
FFWPHI
DEC003-NJC015-033-PAC029-045-091-041430-
/O.NEW.KPHI.FF.W.0032.200804T1128Z-200804T1430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
728 AM EDT Tue Aug 4 2020
The National Weather Service in Mount Holly NJ has issued a
* Flash Flood Warning for...
Northeastern New Castle County in northern Delaware...
North central Salem County in southern New Jersey...
Northwestern Gloucester County in southern New Jersey...
Central Montgomery County in southeastern Pennsylvania...
Northeastern Chester County in southeastern Pennsylvania...
Delaware County in southeastern Pennsylvania...
* Until 1030 AM EDT.
* At 728 AM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Up to two inches of rain have
already fallen. Flash flooding is ongoing or 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
drainage and low lying areas.
* Some locations that could experience flooding include...
Norristown, Chester, Phoenixville, West Norriton, East Norriton,
Carneys Point, Conshohocken, Folcroft, Swarthmore, Collegeville,
Royersford, Trappe, Swedesboro, Schwenksville, Arden, Darby
Township, Cheyney, Bryn Mawr, Trout Lake and Chelsea.
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.
A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.
&&
LAT...LON 4027 7559 4029 7535 3961 7521 3977 7551
FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR
$$
Kruzdlo2 follow-up statements
600
WGUS71 KPHI 041201
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
801 AM EDT Tue Aug 4 2020
DEC003-NJC015-033-PAC029-045-091-041430-
/O.CON.KPHI.FF.W.0032.000000T0000Z-200804T1430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Salem NJ-Gloucester NJ-Montgomery PA-Chester PA-
Delaware PA-
801 AM EDT Tue Aug 4 2020
...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 AM EDT FOR
NORTHEASTERN NEW CASTLE...NORTH CENTRAL SALEM...NORTHWESTERN
GLOUCESTER...CENTRAL MONTGOMERY...NORTHEASTERN CHESTER AND DELAWARE
COUNTIES...
At 755 AM EDT, Doppler radar indicated up to three inches of rain
have fallen across portions of the warned area. Flash flooding is
occurring. Water rescues have been reported in Darby and Marple
Township. Ridley Creek, Chester Creek, and Valley Creek are all
rising rapidly in response to the runoff.
HAZARD...Flash flooding caused by heavy rain.
SOURCE...Radar indicated.
IMPACT...Flooding of small creeks and streams, urban areas,
highways, streets and underpasses as well as other drainage
and low lying areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Protecting yourself from immediate threats to life and safety shall
take priority. Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.
Turn around...don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 4027 7559 4029 7535 3961 7521 3977 7551
FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR
$$
Kruzdlo036 WGUS71 KPHI 041426 FFSPHI Flash Flood Statement National Weather Service Mount Holly NJ 1026 AM EDT Tue Aug 4 2020 DEC003-NJC015-033-PAC029-045-091-041434- /O.EXP.KPHI.FF.W.0032.000000T0000Z-200804T1430Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ New Castle DE-Salem NJ-Gloucester NJ-Montgomery PA-Chester PA- Delaware PA- 1026 AM EDT Tue Aug 4 2020 ...THE FLASH FLOOD WARNING FOR NORTHEASTERN NEW CASTLE...NORTH CENTRAL SALEM...NORTHWESTERN GLOUCESTER...CENTRAL MONTGOMERY... NORTHEASTERN CHESTER AND DELAWARE COUNTIES WILL EXPIRE AT 1030 AM EDT... This flash flood warning will be allowed to expire. It's been updated and replaced with another warning. LAT...LON 4027 7559 4029 7535 3961 7521 3977 7551 $$ Kruzdlo
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 4, 4:50 AM EDT | Tornado Warning | PHI | Sussex | 25 min |
| Aug 4, 5:17 AM EDT | Areal Flood Advisory | PHI | New Castle | 4 hr |
| Aug 4, 7:39 AM EDT | Tornado Warning | PHI | Sussex | 36 min |
| Aug 4, 7:51 AM EDT | Tornado Warning | PHI | Sussex | 24 min |
| Aug 4, 8:15 AM EDT | Tornado Warning | PHI | Kent | 45 min |
| Aug 4, 8:18 AM EDT | Tornado Warning | PHI | Sussex | 27 min |
| Aug 4, 8:27 AM EDT | Tornado Warning | PHI | Kent | 33 min |
| Aug 4, 8:56 AM EDT | Tornado Warning | PHI | Kent, New Castle | 34 min |
| Aug 4, 8:58 AM EDT | Flash Flood Warning | PHI | Kent, New Castle, Sussex | 3 hr |
| Aug 4, 9:06 AM EDT | River Flood Warning | PHI | New Castle | 11 hr |
| Aug 4, 9:23 AM EDT | Flash Flood Warning | PHI | New Castle | 4 hr |
| Aug 4, 9:23 AM EDT | Tornado Warning | PHI | New Castle | 22 min |
| Aug 4, 10:02 AM EDT | Flash Flood Warning | PHI | New Castle | 4 hr |
| Aug 4, 10:38 AM EDT | River Flood Warning | PHI | New Castle | 14 hr |
| Aug 4, 12:27 PM EDT | River Flood Warning | PHI | New Castle | 10 hr |
| Aug 4, 12:48 PM EDT | River Flood Warning | PHI | New Castle | 24 hr |
| Aug 4, 1:59 PM EDT | Areal Flood Warning | PHI | New Castle | 9 hr |
| Aug 4, 7:23 AM EDT | Tornado Warning | PHI | Chester, Delaware, Montgomery, Philadelphia | 20 min |
| Aug 4, 8:11 AM EDT | Flash Flood Warning | PHI | Bucks, Lehigh, Montgomery, Northampton | 4 hr |
| Aug 4, 8:19 AM EDT | River Flood Warning | PHI | Delaware | 15 hr |
| Aug 4, 8:19 AM EDT | Tornado Warning | PHI | Bucks | 26 min |
| Aug 4, 9:29 AM EDT | Tornado Warning | PHI | Monroe, Northampton | 31 min |
| Aug 4, 9:38 AM EDT | Flash Flood Warning | PHI | Monroe, Northampton | 4 hr |
| Aug 4, 9:58 AM EDT | Tornado Warning | PHI | Monroe | 16 min |
| Aug 4, 10:20 AM EDT | Flash Flood Warning | PHI | Bucks, Chester, Delaware, Montgomery, Philadelphia | 4 hr |
| Aug 4, 10:51 AM EDT | Tornado Warning | PHI | Montgomery | 24 min |
| Aug 4, 11:01 AM EDT | Flash Flood Warning | PHI | Bucks | 4 hr |
| Aug 4, 11:13 AM EDT | Areal Flood Advisory | PHI | Berks, Carbon, Lehigh, Monroe, Northampton | 4 hr |
| Aug 4, 11:43 AM EDT | Flash Flood Warning | PHI | Berks, Lehigh, Northampton | 4 hr |
| Aug 4, 12:06 PM EDT | River Flood Warning | PHI | Chester | 11 hr |
| Aug 4, 12:37 PM EDT | River Flood Warning | PHI | Montgomery | 14 hr |
| Aug 4, 12:48 PM EDT | River Flood Warning | PHI | Chester, Delaware | 24 hr |
| Aug 4, 1:01 PM EDT | River Flood Warning | PHI | Bucks | 18 hr |
| Aug 4, 1:12 PM EDT | River Flood Warning | PHI | Berks | 10 hr |
| Aug 4, 1:12 PM EDT | River Flood Warning | PHI | Montgomery | 26 hr |
| Aug 4, 1:12 PM EDT | River Flood Warning | PHI | Chester, Montgomery, Philadelphia | 43 hr |
| Aug 4, 1:12 PM EDT | River Flood Warning | PHI | Montgomery, Philadelphia | 35 hr |
| Aug 4, 2:09 PM EDT | Areal Flood Warning | PHI | Berks, Chester, Delaware, Montgomery, Philadelphia | 15 hr |
| Aug 4, 2:23 PM EDT | River Flood Warning | PHI | Lehigh | 16 hr |
| Aug 4, 2:47 PM EDT | Areal Flood Warning | PHI | Bucks | 9 hr |
| Aug 4, 3:42 PM EDT | Areal Flood Warning | PHI | Lehigh, Northampton | 4 hr |
| Aug 4, 4:39 PM EDT | River Flood Warning | PHI | Monroe | 6 hr |
| Aug 4, 7:29 PM EDT | Areal Flood Warning | PHI | Lehigh, Northampton | 12 hr |
| Aug 3, 8:07 PM EDT | Special Weather Statement | PHI | Hunterdon, Somerset, Warren | 23 min |
| Aug 3, 8:26 PM EDT | Severe Thunderstorm Warning | PHI | Hunterdon, Middlesex, Morris, Somerset | 34 min |
| Aug 3, 9:02 PM EDT | Special Weather Statement | PHI | Morris | 28 min |
| Aug 4, 5:55 AM EDT | Special Marine Warning | PHI | 21 min | |
| Aug 4, 8:38 AM EDT | Special Marine Warning | PHI | 52 min | |
| Aug 4, 9:16 AM EDT | Tornado Warning | PHI | Cumberland | 18 min |
| Aug 4, 9:28 AM EDT | Special Marine Warning | PHI | 32 min | |
| Aug 4, 9:31 AM EDT | Special Marine Warning | PHI | 59 min | |
| Aug 4, 9:42 AM EDT | Tornado Warning | PHI | Atlantic, Cape May | 19 min |
| Aug 4, 10:15 AM EDT | Tornado Warning | PHI | Atlantic, Burlington, Ocean | 14 min |
| Aug 4, 11:00 AM EDT | Tornado Warning | PHI | Monmouth, Ocean | 11 min |
| Aug 4, 11:59 AM EDT | Areal Flood Advisory | PHI | Hunterdon, Middlesex, Monmouth, Morris, Somerset | 4 hr |
| Aug 4, 2:33 PM EDT | River Flood Warning | PHI | Hunterdon, Somerset | 5 hr |
| Aug 4, 4:37 PM EDT | Areal Flood Warning | PHI | Cumberland, Salem | 10 hr |
| Aug 4, 5:04 PM EDT | Small Craft Advisory | PHI | 14 hr | |
| Aug 4, 5:30 PM EDT | Coastal Flood Statement | PHI | Ocean | 103 min |
Nearby
Flash Flood Warnings in Pennsylvania, 2020Flash Flood Warnings in New Jersey, 2020Flash Flood Warnings in Delaware, 2020Every 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.