Alert archive / Pennsylvania / Flash Flood Warnings in 2020

Flash Flood Warning 27, NWS Philadelphia/Mount Holly

July 24, 2020Bucks County, Montgomery County, Philadelphia County, Pennsylvania; Burlington County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 24, 2020, 2:26 PM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania; Burlington County, New Jersey. It was in force for 2 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: Jul 24, 2020, 2:26 PM EDT (18:26 UTC)
Expired: Jul 24, 2020, 4:31 PM EDT
In force: 2 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Burlington County, NJ, Bucks County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 48 km from the middle of the area, began a volume at 18:28 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
Jul 24, 3:24 PM EDT	FLASH FLOOD	1 Ssw Summerdale, PA	FRANKFORD CREEK CRESTED AT 8.04 FT, OR IN MODERATE FLOOD STAGE.

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 12:00Z, 6.4 hours before the alert went out and 202 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: 473 J/kg
Mixed-layer CIN: -70 J/kg
Mixed-layer LCL: 792 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: -17 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

456 
WGUS51 KPHI 241826
FFWPHI
NJC005-PAC017-091-101-242230-
/O.NEW.KPHI.FF.W.0027.200724T1826Z-200724T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
226 PM EDT Fri Jul 24 2020

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Northwestern Burlington County in southern New Jersey...
  East central Montgomery County in southeastern Pennsylvania...
  South central Bucks County in southeastern Pennsylvania...
  Northeastern Philadelphia County in southeastern Pennsylvania...

* Until 630 PM EDT.

* At 226 PM 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...
  Philadelphia, Bensalem, Mount Laurel, Willingboro, Burlington,
  Bristol, Riverside, Palmyra, Beverly, Rockledge, Bryn Athyn,
  Wissinoming, Ramblewood, Feasterville-Trevose, Northeast
  Philadelphia, Feasterville, Tacony, Marlton, Andalusia and
  Holmesburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...


Turn around...don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 4010 7480 3991 7487 3990 7493 3996 7502
      3998 7501 4000 7504 3999 7507 4002 7514
      4018 7504

FLASH FLOOD...RADAR INDICATED

$$

NC

2 follow-up statements

708 
WGUS71 KPHI 241943
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
343 PM EDT Fri Jul 24 2020

NJC005-PAC017-091-101-242230-
/O.CON.KPHI.FF.W.0027.000000T0000Z-200724T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Burlington NJ-Montgomery PA-Bucks PA-Philadelphia PA-
343 PM EDT Fri Jul 24 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM EDT FOR
NORTHWESTERN BURLINGTON...EAST CENTRAL MONTGOMERY...SOUTH CENTRAL
BUCKS AND NORTHEASTERN PHILADELPHIA COUNTIES...

Following earlier heavier rainfall the water level has risen in 
several small streams in the warned area, with the most noticeable 
rise at Frankford Creek in Philadelphia where as of 340 PM moderate 
flood stage had been reached.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...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 could experience flooding include...
Philadelphia, Bensalem, Mount Laurel, Willingboro, Burlington,
Bristol, Riverside, Palmyra, Beverly, Rockledge, Bryn Athyn,
Wissinoming, Ramblewood, Feasterville-Trevose, Northeast
Philadelphia, Feasterville, Tacony, Marlton, Andalusia and
Holmesburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...


Turn around...don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 4010 7480 3991 7487 3990 7493 3996 7502
      3998 7501 4000 7504 3999 7507 4002 7514
      4018 7504

FLASH FLOOD...GAUGE INDICATED

$$

NC

547 
WGUS71 KPHI 242031
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
431 PM EDT Fri Jul 24 2020

NJC005-PAC017-091-101-242040-
/O.CAN.KPHI.FF.W.0027.000000T0000Z-200724T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Burlington NJ-Montgomery PA-Bucks PA-Philadelphia PA-
431 PM EDT Fri Jul 24 2020

...THE FLASH FLOOD WARNING FOR NORTHWESTERN BURLINGTON...EAST CENTRAL
MONTGOMERY...SOUTH CENTRAL BUCKS AND NORTHEASTERN PHILADELPHIA
COUNTIES IS CANCELLED...

The heavy rain has ended. Flood waters have receded. Flooding is no
longer expected to pose a threat. Please continue to heed any
remaining road closures.

LAT...LON 4010 7480 3991 7487 3990 7493 3996 7502
      3998 7501 4000 7504 3999 7507 4002 7514
      4018 7504

$$

NC

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 23, 10:26 PM EDT	Severe Thunderstorm Warning	PHI	Chester	49 min
Jul 23, 10:44 PM EDT	Areal Flood Advisory	PHI	Chester	2 hr
Jul 23, 11:10 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware	2 hr
Jul 23, 11:16 PM EDT	Severe Thunderstorm Warning	PHI	Delaware	44 min
Jul 23, 11:38 PM EDT	Special Weather Statement	PHI	Chester	37 min
Jul 23, 11:44 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	46 min
Jul 24, 12:24 AM EDT	Flash Flood Warning	PHI	Chester	114 min
Jul 24, 12:32 AM EDT	Special Weather Statement	PHI	Bucks, Montgomery	28 min
Jul 24, 12:42 AM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	48 min
Jul 24, 1:13 AM EDT	Severe Thunderstorm Warning	PHI	Bucks	62 min
Jul 24, 10:43 AM EDT	Flash Flood Warning	PHI	Philadelphia	76 min
Jul 24, 1:43 PM EDT	Areal Flood Advisory	PHI	Bucks, Philadelphia	3 hr
Jul 24, 2:19 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	2 hr
Jul 23, 8:04 PM EDT	Severe Thunderstorm Warning	PHI	Middlesex, Monmouth	26 min
Jul 23, 11:27 PM EDT	Special Marine Warning	PHI		63 min
Jul 24, 12:14 AM EDT	Special Weather Statement	PHI	Middlesex	31 min
Jul 24, 12:23 AM EDT	Severe Thunderstorm Warning	PHI	Mercer, Middlesex, Monmouth, Somerset	52 min
Jul 24, 12:31 AM EDT	Areal Flood Advisory	PHI	Hunterdon, Mercer, Middlesex, Monmouth, Somerset	119 min
Jul 24, 12:51 AM EDT	Special Marine Warning	PHI		54 min
Jul 24, 1:28 AM EDT	Flash Flood Warning	PHI	Mercer, Middlesex, Monmouth, Somerset	4 hr
Jul 24, 1:36 AM EDT	Special Marine Warning	PHI		84 min
Jul 24, 2:18 AM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Middlesex, Morris, Somerset	42 min
Jul 24, 5:04 AM EDT	Special Marine Warning	PHI		56 min
Jul 24, 11:42 AM EDT	Special Marine Warning	PHI		63 min
Jul 24, 12:43 PM EDT	Areal Flood Advisory	PHI	Ocean	3 hr
Jul 24, 1:09 PM EDT	Areal Flood Advisory	PHI	Monmouth, Ocean	110 min
Jul 24, 1:40 PM EDT	Special Weather Statement	PHI	Atlantic	35 min
Jul 24, 2:02 PM EDT	Areal Flood Advisory	PHI	Atlantic, Burlington, Camden, Gloucester	3 hr
Jul 24, 2:39 PM EDT	Areal Flood Advisory	PHI	Burlington, Ocean	3 hr
Jul 24, 2:42 PM EDT	Areal Flood Advisory	PHI	Burlington, Ocean	2 hr
Jul 24, 3:34 PM EDT	Flash Flood Warning	PHI	Atlantic, Burlington, Ocean	2 hr
Jul 24, 4:22 PM EDT	Areal Flood Advisory	PHI	Atlantic, Cape May	3 hr
Jul 24, 4:58 PM EDT	Areal Flood Advisory	PHI	Cape May	2 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2020 Flash Flood Warnings in New Jersey, 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.