Alert archive / New Jersey / Flash Flood Warnings in 2021

Flash Flood Warning 46, NWS Philadelphia/Mount Holly

August 19, 2021Bucks County, Philadelphia County, Pennsylvania; Burlington County, Camden County, Mercer County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 19, 2021, 2:13 AM EDT for Bucks County, Philadelphia County, Pennsylvania; Burlington County, Camden County, Mercer County, New Jersey. It was in force for 4 hr. 2 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, 2:13 AM EDT (06:13 UTC)
Expired
Aug 19, 2021, 6:09 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Burlington County, NJ, Camden County, NJ, Mercer County, NJ, Bucks County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 48 km from the middle of the area, began a volume at 06:13 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 19, 2:51 AM EDTFLASH FLOOD1 Nnw Holmesburg, PATHE PENNYPACK CREEK REACHED MINOR FLOOD STAGE WITH A CREST OF 7.58 FT.
Aug 19, 2:51 AM EDTFLASH FLOOD1 Ssw Summerdale, PAFRANKFORD CREEK CRESTED AT MODERATE FLOOD STAGE OF 9.62 FT.

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, 6.2 hours before the alert went out and 199 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, Brookhaven, NY at 00:00Z on 2021-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 491 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, Brookhaven, NY at 00:00Z on 2021-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.1939Sfc1 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
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

Open this sounding in Storm Lab

The text

As transmitted.

257 
WGUS51 KPHI 190613
FFWPHI
NJC005-007-021-PAC017-101-191015-
/O.NEW.KPHI.FF.W.0046.210819T0613Z-210819T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
213 AM EDT Thu Aug 19 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  South Central Mercer County in central New Jersey...
  Northwestern Burlington County in southern New Jersey...
  Northern Camden County in southern New Jersey...
  Southeastern Bucks County in southeastern Pennsylvania...
  Northeastern Philadelphia County in southeastern Pennsylvania...

* Until 615 AM EDT.

* At 213 AM EDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  0.5 and 1 inch of rain has fallen, with heavier rain still to 
  come. Additional rainfall amounts of 1 to 2 inches are possible in 
  the warned area. Flash flooding is 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, Trenton, Camden, Bensalem, Willingboro, Florence, 
  Burlington, Bristol, Riverside, Palmyra, Bordentown, and Beverly.

This includes the following highways...
	New Jersey Turnpike between exits 6 and 6A.
	Pennsylvania Turnpike between mile markers 352 and 359.
	Interstate 95 in Pennsylvania between mile markers 25 and 40.
	Interstate 295 in New Jersey between mile markers 38 and 61.
	Interstate 195 in New Jersey between mile markers 0 and 1.

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 3997 7509 3999 7514 4025 7485 4017 7465
      3993 7494

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

JEO
2 follow-up statements
229 
WGUS71 KPHI 190653
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
253 AM EDT Thu Aug 19 2021

NJC005-007-190703-
/O.CAN.KPHI.FF.W.0046.000000T0000Z-210819T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Burlington NJ-Camden NJ-
253 AM EDT Thu Aug 19 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN BURLINGTON AND 
NORTHERN CAMDEN COUNTIES...

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

LAT...LON 3999 7510 3999 7514 4025 7485 4017 7465
      4017 7467 4017 7468 4018 7469 4018 7470
      4018 7471 4017 7471 4017 7470 4016 7471
      4015 7472 4014 7473 4012 7479 4013 7482
      4010 7483 4006 7496

$$

NJC021-PAC017-101-191015-
/O.CON.KPHI.FF.W.0046.000000T0000Z-210819T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Bucks PA-Philadelphia PA-
253 AM EDT Thu Aug 19 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 615 AM EDT THIS 
MORNING FOR SOUTH CENTRAL MERCER, SOUTHEASTERN BUCKS, AND 
NORTHEASTERN PHILADELPHIA COUNTIES...

At 253 AM EDT, Doppler radar and automated rain gauges indicated 
thunderstorms producing heavy rain across the warned area. Between 1 
and 3 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 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, Trenton, Bensalem, Burlington, Bristol, Beverly, 
  Yardley, Tullytown, Langhorne, Levittown, Langhorn, and 
  Florence-Roebling.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 351 and 359.
	Interstate 95 in Pennsylvania between mile markers 27 and 40.
	Interstate 295 in New Jersey between mile markers 58 and 61.
	Interstate 195 in New Jersey between mile markers 0 and 1.

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 3999 7510 3999 7514 4025 7485 4017 7465
      4017 7467 4017 7468 4018 7469 4018 7470
      4018 7471 4017 7471 4017 7470 4016 7471
      4015 7472 4014 7473 4012 7479 4013 7482
      4010 7483 4006 7496

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

JEO
594 
WGUS71 KPHI 191009
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
609 AM EDT Thu Aug 19 2021

NJC021-PAC017-101-191019-
/O.CAN.KPHI.FF.W.0046.000000T0000Z-210819T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Bucks PA-Philadelphia PA-
609 AM EDT Thu Aug 19 2021

...FLASH FLOOD WARNING FOR SOUTH CENTRAL MERCER, SOUTHEASTERN BUCKS, 
AND NORTHEASTERN PHILADELPHIA COUNTIES HAS BEEN REPLACED WITH A 
FLOOD WARNING...

LAT...LON 3999 7510 3999 7514 4025 7485 4017 7465
      4017 7467 4017 7468 4018 7469 4018 7470
      4018 7471 4017 7471 4017 7470 4016 7471
      4015 7472 4014 7473 4012 7479 4013 7482
      4010 7483 4006 7496

$$

JEO

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 8:53 PM EDTAreal Flood AdvisoryPHIBerks3 hr
Aug 18, 9:10 PM EDTAreal Flood AdvisoryPHILehigh, Monroe, Northampton3 hr
Aug 18, 9:30 PM EDTFlash Flood WarningPHIBerks2 hr
Aug 18, 9:35 PM EDTAreal Flood AdvisoryPHIBerks, Lehigh3 hr
Aug 18, 9:45 PM EDTAreal Flood AdvisoryPHIBerks3 hr
Aug 18, 9:47 PM EDTSpecial Weather StatementPHIBerks58 min
Aug 18, 10:16 PM EDTFlash Flood WarningPHIBerks, Lehigh3 hr
Aug 18, 10:44 PM EDTFlash Flood WarningPHILehigh, Monroe, Northampton4 hr
Aug 18, 10:50 PM EDTFlash Flood WarningPHIBucks, Chester, Montgomery4 hr
Aug 18, 11:19 PM EDTAreal Flood AdvisoryPHIBucks, Lehigh, Northampton3 hr
Aug 18, 11:19 PM EDTSpecial Weather StatementPHIBucks, Chester, Montgomery41 min
Aug 18, 11:47 PM EDTFlash Flood WarningPHIChester2 hr
Aug 19, 12:04 AM EDTSpecial Weather StatementPHIBucks, Delaware, Montgomery71 min
Aug 19, 12:26 AM EDTTornado WarningPHIBucks, Montgomery34 min
Aug 19, 12:31 AM EDTFlash Flood WarningPHIBucks, Chester, Delaware, Montgomery4 hr
Aug 19, 12:44 AM EDTRiver Flood WarningPHIChester5 hr
Aug 19, 12:47 AM EDTTornado WarningPHIChester, Delaware, Montgomery, Philadelphia28 min
Aug 19, 12:48 AM EDTTornado WarningPHIBucks27 min
Aug 19, 1:14 AM EDTSpecial Weather StatementPHIBucks, Delaware, Philadelphia91 min
Aug 19, 1:30 AM EDTFlash Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia4 hr
Aug 19, 2:05 AM EDTAreal Flood AdvisoryPHIBucks3 hr
Aug 19, 4:33 AM EDTAreal Flood WarningPHIChester, Delaware4 hr
Aug 19, 6:09 AM EDTAreal Flood WarningPHIBucks, Philadelphia3 hr
Aug 19, 8:50 AM EDTAreal Flood WarningPHIMontgomery, Philadelphia3 hr
Aug 19, 10:40 AM EDTAreal Flood WarningPHIDelaware3 hr
Aug 19, 1:32 AM EDTSmall Craft AdvisoryPHI5 hr
Aug 19, 2:33 AM EDTTornado WarningPHIMorris27 min
Aug 19, 2:40 AM EDTTornado WarningPHIMorris24 min
Aug 19, 3:09 AM EDTTornado WarningPHIMercer, Middlesex, Monmouth36 min

Nearby

Flash Flood Warnings in New Jersey, 2021Flash 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.