Alert archive / Pennsylvania / Flash Flood Warnings in 2021
Flash Flood Warning 45, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 19, 2021, 1:30 AM EDT for 4 counties in Pennsylvania. It was in force for 4 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 19, 2021, 1:30 AM EDT (05:30 UTC)
- Expired
- Aug 19, 2021, 5:30 AM EDT
- In force
- 4 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Flood severity
- None
Counties Bucks County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 63 km from the middle of the area, began a volume at 05:30 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 19, 1:48 AM EDT | FLASH FLOOD | 1 Sse Flourtown, PA | WATER RESCUE IN THE AREA OF PAPER MILL RD AT HARSTON LN. |
| Aug 19, 2:09 AM EDT | FLASH FLOOD | Abington, PA | WATER RESCUE ON HIGHLAND AVE. |
| Aug 19, 2:11 AM EDT | FLASH FLOOD | 1 Nnw Abington, PA | DELAYED REPORT. WATER RESCUE NEAR THE INTERSECTION OF EASTON ROAD AND WOODLAND ROAD. TIME BASED ON DISPATCH REPORT. |
| Aug 19, 2:30 AM EDT | FLASH FLOOD | 1 E Lower Moreland Twp, PA | DELAYED REPORT OF FLOODING ON PHILMONT AVENUE, FORCING ITS CLOSURE NEAR PINE ROAD. TIME BASED ON NEARBY REPORTS. |
| Aug 19, 2:45 AM EDT | FLASH FLOOD | 1 Se Manayunk, PA | THE GAUGE ON THE WISSAHICKON CREEK NEAR WISSAHICKON CRESTED AT MINOR FLOOD STAGE OF 6.30 FEET. |
| Aug 19, 2:45 AM EDT | FLASH FLOOD | 1 S Penn Wynne, PA | COBBS CREEK CRESTED AT MODERATE FLOOD STAGE OF 8.35 FT. |
| Aug 19, 2:45 AM EDT | FLASH FLOOD | Cheltenham, PA | WATER RESCUE ON ASHMEADE RD. |
| Aug 19, 2:47 AM EDT | FLOOD | Jenkintown, PA | DELAYED REPORT. FLOODING ON SHOEMAKER AVENUE AND CEDAR STREET. TIME BASED ON DISPATCH REPORT. |
| Aug 19, 2:51 AM EDT | FLASH FLOOD | 1 Ssw Summerdale, PA | FRANKFORD CREEK CRESTED AT MODERATE FLOOD STAGE OF 9.62 FT. |
| Aug 19, 2:55 AM EDT | FLASH FLOOD | 1 Sse Abington, PA | WATER RESCUE ON BROOK RD. |
| Aug 19, 3:19 AM EDT | HEAVY RAIN 3.73 | Wynnewood, PA | STORM TOTAL. |
| Aug 19, 3:26 AM EDT | FLASH FLOOD | 1 Sw Shawmont, PA | DELAYED REPORT. WATER RESCUE ON THE RAMP TO SCHUYLKILL EXPRESSWAY VIA HOLLOW 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
Brookhaven, NY (KOKX), launched 00:00Z, 5.5 hours before the alert went out and 210 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
- 491 J/kg
- Mixed-layer CIN
- -11 J/kg
- Mixed-layer LCL
- 580 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 62 m²/s²
- 0-3 km storm-relative helicity
- 103 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
608
WGUS51 KPHI 190530
FFWPHI
PAC017-045-091-101-190930-
/O.NEW.KPHI.FF.W.0045.210819T0530Z-210819T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
130 AM EDT Thu Aug 19 2021
The National Weather Service in Mount Holly has issued a
* Flash Flood Warning for...
South Central Bucks County in southeastern Pennsylvania...
East Central Delaware County in southeastern Pennsylvania...
Southeastern Montgomery County in southeastern Pennsylvania...
Northwestern Philadelphia County in southeastern Pennsylvania...
* Until 530 AM EDT.
* At 130 AM EDT, Doppler radar and automated rain gauges indicated
thunderstorms producing heavy rain across the warned area. Between
0.5 and 1.5 inches of rain have fallen. Heavier rain is
approaching the area, and 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 and automated gauges.
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...
Philadelphia, Yeadon, Hatboro, Folcroft, Swarthmore, Jenkintown,
Narberth, East Lansdowne, Rockledge, Abington, Langhorne, and Bryn
Athyn.
This includes the following highways...
Pennsylvania Turnpike between mile markers 339 and 351.
Interstate 76 in Pennsylvania between mile markers 336 and 346.
Interstate 676 in Pennsylvania near mile marker 0.
Interstate 476 in Pennsylvania between mile markers 2 and 3.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 4027 7509 4021 7489 4017 7493 3989 7524
3989 7526 3990 7538
FLASH FLOOD...RADAR AND GAUGE INDICATED
$$
JEO2 follow-up statements
080
WGUS71 KPHI 190552
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
152 AM EDT Thu Aug 19 2021
PAC017-045-091-101-190930-
/O.CON.KPHI.FF.W.0045.000000T0000Z-210819T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bucks PA-Delaware PA-Montgomery PA-Philadelphia PA-
152 AM EDT Thu Aug 19 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 AM EDT EARLY THIS
MORNING FOR SOUTH CENTRAL BUCKS, EAST CENTRAL DELAWARE, SOUTHEASTERN
MONTGOMERY, AND NORTHWESTERN PHILADELPHIA COUNTIES...
At 152 AM EDT, Doppler radar and automated rain gauges indicated
thunderstorms producing heavy rain across the warned area. Between 2
and 3 inches of rain have fallen. Additional rainfall amounts of 1
to 2 inches are possible in the warned area. This will likely lead
to significant flash flooding in the warned area, much of which is
highly urbanized and especially susceptible to flooding. Flash
flooding is ongoing or expected to begin shortly.
HAZARD...Life threatening flash flooding caused by thunderstorms.
SOURCE...Radar and automated gauges.
IMPACT...Life threatening flash flooding of creeks and streams,
urban areas, highways, streets, and underpasses.
Some locations that will experience flash flooding include...
Philadelphia, Yeadon, Hatboro, Folcroft, Swarthmore, Jenkintown,
Narberth, East Lansdowne, Rockledge, Abington, Langhorne, and Bryn
Athyn.
This includes the following highways...
Pennsylvania Turnpike between mile markers 339 and 351.
Interstate 76 in Pennsylvania between mile markers 336 and 346.
Interstate 676 in Pennsylvania near mile marker 0.
Interstate 476 in Pennsylvania near mile marker 3...and
near mile marker 7.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
&&
LAT...LON 4027 7509 4021 7489 4017 7493 3989 7524
3989 7526 3990 7538
FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
JEO807
WGUS71 KPHI 190925
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
525 AM EDT Thu Aug 19 2021
PAC017-045-091-101-190935-
/O.EXP.KPHI.FF.W.0045.000000T0000Z-210819T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bucks PA-Delaware PA-Montgomery PA-Philadelphia PA-
525 AM EDT Thu Aug 19 2021
...FLASH FLOOD WARNING WILL EXPIRE AT 530 AM EDT EARLY THIS MORNING
FOR SOUTH CENTRAL BUCKS, EAST CENTRAL DELAWARE, SOUTHEASTERN
MONTGOMERY, AND NORTHWESTERN PHILADELPHIA COUNTIES...
Flood waters are receding. The heavy rain has ended. Please continue
to heed remaining road closures.
LAT...LON 4027 7509 4021 7489 4017 7493 3989 7524
3989 7526 3990 7538
$$
JEOThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 8:53 PM EDT | Areal Flood Advisory | PHI | Berks | 3 hr |
| Aug 18, 9:10 PM EDT | Areal Flood Advisory | PHI | Lehigh, Monroe, Northampton | 3 hr |
| Aug 18, 9:30 PM EDT | Flash Flood Warning | PHI | Berks | 2 hr |
| Aug 18, 9:35 PM EDT | Areal Flood Advisory | PHI | Berks, Lehigh | 3 hr |
| Aug 18, 9:45 PM EDT | Areal Flood Advisory | PHI | Berks | 3 hr |
| Aug 18, 9:47 PM EDT | Special Weather Statement | PHI | Berks | 58 min |
| Aug 18, 10:16 PM EDT | Flash Flood Warning | PHI | Berks, Lehigh | 3 hr |
| Aug 18, 10:44 PM EDT | Flash Flood Warning | PHI | Lehigh, Monroe, Northampton | 4 hr |
| Aug 18, 10:50 PM EDT | Flash Flood Warning | PHI | Bucks, Chester, Montgomery | 4 hr |
| Aug 18, 11:19 PM EDT | Areal Flood Advisory | PHI | Bucks, Lehigh, Northampton | 3 hr |
| Aug 18, 11:19 PM EDT | Special Weather Statement | PHI | Bucks, Chester, Montgomery | 41 min |
| Aug 18, 11:47 PM EDT | Flash Flood Warning | PHI | Chester | 2 hr |
| Aug 19, 12:04 AM EDT | Special Weather Statement | PHI | Bucks, Delaware, Montgomery | 71 min |
| Aug 19, 12:26 AM EDT | Tornado Warning | PHI | Bucks, Montgomery | 34 min |
| Aug 19, 12:31 AM EDT | Flash Flood Warning | PHI | Bucks, Chester, Delaware, Montgomery | 4 hr |
| Aug 19, 12:44 AM EDT | River Flood Warning | PHI | Chester | 5 hr |
| Aug 19, 12:47 AM EDT | Tornado Warning | PHI | Chester, Delaware, Montgomery, Philadelphia | 28 min |
| Aug 19, 12:48 AM EDT | Tornado Warning | PHI | Bucks | 27 min |
| Aug 19, 1:14 AM EDT | Special Weather Statement | PHI | Bucks, Delaware, Philadelphia | 91 min |
| Aug 19, 2:05 AM EDT | Areal Flood Advisory | PHI | Bucks | 3 hr |
| Aug 19, 2:13 AM EDT | Flash Flood Warning | PHI | Bucks, Philadelphia | 4 hr |
| Aug 19, 4:33 AM EDT | Areal Flood Warning | PHI | Chester, Delaware | 4 hr |
| Aug 19, 6:09 AM EDT | Areal Flood Warning | PHI | Bucks, Philadelphia | 3 hr |
| Aug 19, 8:50 AM EDT | Areal Flood Warning | PHI | Montgomery, Philadelphia | 3 hr |
| Aug 19, 10:40 AM EDT | Areal Flood Warning | PHI | Delaware | 3 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.