Alert archive / Pennsylvania / Flash Flood Warnings in 2021
Flash Flood Warning 5, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 8, 2021, 1:35 PM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 5 hr. 1 report 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
- Jun 8, 2021, 1:35 PM EDT (17:35 UTC)
- Expired
- Jun 8, 2021, 6:25 PM EDT
- In force
- 5 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Flood severity
- None
Counties Chester County, PA, Delaware County, PA, Montgomery County, PA
The radar
The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 17:35 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 |
|---|---|---|---|
| Jun 8, 5:30 PM EDT | FLASH FLOOD | 1 E Chadds Ford Twp, PA | BRIDGE FLOODED OUT ON RING RD. |
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, 5.6 hours before the alert went out and 194 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
- 254 J/kg
- Mixed-layer CIN
- -121 J/kg
- Mixed-layer LCL
- 1088 m above ground
- 0-6 km bulk shear
- 12 kt
- 0-1 km storm-relative helicity
- -39 m²/s²
- 0-3 km storm-relative helicity
- 23 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
807
WGUS51 KPHI 081735
FFWPHI
PAC029-045-091-082145-
/O.NEW.KPHI.FF.W.0005.210608T1735Z-210608T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
135 PM EDT Tue Jun 8 2021
The National Weather Service in Mount Holly has issued a
* Flash Flood Warning for...
Southeastern Chester County in southeastern Pennsylvania...
Delaware County in southeastern Pennsylvania...
South Central Montgomery County in southeastern Pennsylvania...
* Until 545 PM EDT.
* At 135 PM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 1 and 2 inches of rain
have fallen. Additional rainfall amounts of 1 to 2 inches are
possible in the warned area. Flash flooding is ongoing or expected
to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
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 may experience flash flooding include...
West Chester, Norristown, Chester, West Norriton, East Norriton,
Westtown, Conshohocken, Swarthmore, Kennett Square, Narberth, and
East Lansdowne.
This includes the following highways...
Pennsylvania Turnpike between mile markers 322 and 331.
Interstate 95 in Pennsylvania between mile markers 0 and 4.
Interstate 76 in Pennsylvania between mile markers 327 and 338.
Interstate 476 in Pennsylvania between mile markers 1 and 18.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 3984 7580 4016 7538 4001 7521 3997 7528
3996 7525 3981 7542 3983 7550 3984 7558
3982 7566 3979 7572
FLASH FLOOD...RADAR INDICATED
$$
Iovino4 follow-up statements
147
WGUS71 KPHI 081903
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
303 PM EDT Tue Jun 8 2021
PAC029-045-091-082145-
/O.CON.KPHI.FF.W.0005.000000T0000Z-210608T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Delaware PA-Montgomery PA-
303 PM EDT Tue Jun 8 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM EDT THIS
AFTERNOON FOR SOUTHEASTERN CHESTER, DELAWARE, AND SOUTH CENTRAL
MONTGOMERY COUNTIES...
At 303 PM EDT, Doppler radar indicated another round of
thunderstorms producing heavy rain approaching the warned area.
Between 1 and 2.5 inches of rain have fallen in spots. Additional
rainfall amounts of 1 to 2 inches are possible in the warned area.
Flash flooding is ongoing or expected to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
IMPACT...Flooding of small creeks and streams, urban areas,
highways, streets, and underpasses as well as other
drainage and low lying areas.
Some locations that may experience flash flooding include...
West Chester, Norristown, Chester, West Norriton, East Norriton,
Westtown, Conshohocken, Swarthmore, Kennett Square, Narberth, and
East Lansdowne.
This includes the following highways...
Pennsylvania Turnpike between mile markers 322 and 331.
Interstate 95 in Pennsylvania between mile markers 0 and 4.
Interstate 76 in Pennsylvania between mile markers 327 and 338.
Interstate 476 in Pennsylvania between mile markers 1 and 18.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 3984 7580 4016 7538 4001 7521 3997 7528
3996 7525 3981 7542 3983 7550 3984 7558
3982 7566 3979 7572
FLASH FLOOD...RADAR INDICATED
$$
Iovino123
WGUS51 KPHI 082031
FFWPHI
PAC029-045-091-082330-
/O.EXT.KPHI.FF.W.0005.000000T0000Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
431 PM EDT Tue Jun 8 2021
The National Weather Service in Mount Holly has extended the
* Flash Flood Warning for...
Southeastern Chester County in southeastern Pennsylvania...
Delaware County in southeastern Pennsylvania...
South Central Montgomery County in southeastern Pennsylvania...
* Until 730 PM EDT.
* At 431 PM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 1 and 4 inches of rain
have fallen. Additional rainfall amounts of 0.5 to 1 inch are
possible in the warned area. Flash flooding is ongoing or expected
to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
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 will experience flash flooding include...
West Chester, Norristown, Chester, West Norriton, East Norriton,
Westtown, Conshohocken, Swarthmore, Kennett Square, Narberth, and
East Lansdowne.
This includes the following highways...
Pennsylvania Turnpike between mile markers 322 and 331.
Interstate 95 in Pennsylvania between mile markers 0 and 4.
Interstate 76 in Pennsylvania between mile markers 327 and 338.
Interstate 476 in Pennsylvania between mile markers 1 and 18.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 3984 7580 4016 7538 4001 7521 3997 7528
3996 7525 3981 7542 3983 7550 3984 7558
3982 7566 3979 7572
FLASH FLOOD...RADAR INDICATED
$$
Iovino167
WGUS71 KPHI 082056
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
456 PM EDT Tue Jun 8 2021
PAC091-082106-
/O.CAN.KPHI.FF.W.0005.000000T0000Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-
456 PM EDT Tue Jun 8 2021
...FLASH FLOOD WARNING IS CANCELLED FOR SOUTH CENTRAL MONTGOMERY
COUNTY...
Flooding is no longer expected to pose a threat. Please continue to
heed remaining road closures.
LAT...LON 3984 7580 4010 7546 4009 7546 4010 7542
4006 7539 4007 7537 4002 7532 4002 7531
3997 7528 3996 7525 3981 7542 3983 7550
3984 7558 3982 7566 3979 7572
$$
PAC029-045-082330-
/O.CON.KPHI.FF.W.0005.000000T0000Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Delaware PA-
456 PM EDT Tue Jun 8 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM EDT THIS
EVENING FOR SOUTHEASTERN CHESTER AND DELAWARE COUNTIES...
At 456 PM EDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Between 1 and 4 inches of rain have
fallen. Additional rainfall amounts of 0.5 to 1 inch are possible in
the warned area. Flash flooding is ongoing or expected to begin
shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
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 will experience flash flooding include...
West Chester, Chester, Westtown, Swarthmore, Kennett Square, East
Lansdowne, Cheyney, Gradyville, Concordville, Lima, Chelsea, and
Elam.
This includes the following highways...
Pennsylvania Turnpike between mile markers 322 and 326.
Interstate 95 in Pennsylvania between mile markers 0 and 4.
Interstate 476 in Pennsylvania between mile markers 1 and 14.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 3984 7580 4010 7546 4009 7546 4010 7542
4006 7539 4007 7537 4002 7532 4002 7531
3997 7528 3996 7525 3981 7542 3983 7550
3984 7558 3982 7566 3979 7572
FLASH FLOOD...RADAR INDICATED
$$
Iovino072
WGUS71 KPHI 082225
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
625 PM EDT Tue Jun 8 2021
PAC029-045-082235-
/O.CAN.KPHI.FF.W.0005.000000T0000Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Delaware PA-
625 PM EDT Tue Jun 8 2021
...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHEASTERN CHESTER AND
DELAWARE COUNTIES...
The heavy rain has ended but significant flooding continues in the
Brandywine Creek basin. A Flood Warning is in effect for the
Brandywine Creek basin in Chester County and far western Delaware
County until 8:00 AM on Wednesday. Do not drive on flooded roadways.
LAT...LON 3984 7580 4010 7546 4009 7546 4010 7542
4006 7539 4007 7537 4002 7532 4002 7531
3997 7528 3996 7525 3981 7542 3983 7550
3984 7558 3982 7566 3979 7572
$$
IovinoThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 8, 11:54 AM EDT | Areal Flood Advisory | PHI | Monroe | 2 hr |
| Jun 8, 12:34 PM EDT | Flash Flood Warning | PHI | Monroe | 2 hr |
| Jun 8, 12:40 PM EDT | Special Weather Statement | PHI | Monroe | 35 min |
| Jun 8, 1:09 PM EDT | Special Weather Statement | PHI | Monroe | 21 min |
| Jun 8, 1:17 PM EDT | Special Weather Statement | PHI | Chester | 13 min |
| Jun 8, 1:18 PM EDT | Areal Flood Advisory | PHI | Chester, Delaware, Montgomery, Philadelphia | 3 hr |
| Jun 8, 1:24 PM EDT | Special Weather Statement | PHI | Delaware | 21 min |
| Jun 8, 1:27 PM EDT | Areal Flood Advisory | PHI | Carbon, Lehigh, Monroe, Northampton | 3 hr |
| Jun 8, 2:07 PM EDT | Special Weather Statement | PHI | Bucks | 23 min |
| Jun 8, 2:19 PM EDT | Areal Flood Advisory | PHI | Bucks | 2 hr |
| Jun 8, 2:43 PM EDT | Special Weather Statement | PHI | Montgomery | 32 min |
| Jun 8, 3:15 PM EDT | Special Weather Statement | PHI | Chester | 30 min |
| Jun 8, 3:21 PM EDT | Flash Flood Warning | PHI | Chester, Montgomery | 3 hr |
| Jun 8, 3:43 PM EDT | Special Weather Statement | PHI | Chester | 32 min |
| Jun 8, 4:20 PM EDT | Special Weather Statement | PHI | Chester | 25 min |
| Jun 8, 4:25 PM EDT | River Flood Warning | PHI | Chester | 11 hr |
| Jun 8, 6:21 PM EDT | Areal Flood Warning | PHI | Chester, Delaware | 15 hr |
| Jun 8, 7:14 PM EDT | River Flood Warning | PHI | Chester, Delaware | 18 hr |
Nearby
Flash Flood Warnings in Pennsylvania, 2021Every flash flood warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.