Alert archive / Pennsylvania / Areal Flood Warnings in 2021

Areal Flood Warning 16, NWS Philadelphia/Mount Holly

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

NWS Philadelphia/Mount Holly issued this areal flood warning at Aug 19, 2021, 6:09 AM EDT for Bucks County, Philadelphia County, Pennsylvania; Mercer County, New Jersey. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 19, 2021, 6:09 AM EDT (10:09 UTC)
Expired
Aug 19, 2021, 9:00 AM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

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

The radar

The Philadelphia radar (KDIX), 40 km from the middle of the area, began a volume at 10:10 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.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 10.2 hours before the alert went out and 185 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.

593 
WGUS41 KPHI 191009
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
609 AM EDT Thu Aug 19 2021

NJC021-PAC017-101-191300-
/O.NEW.KPHI.FA.W.0016.210819T1009Z-210819T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Bucks PA-Philadelphia PA-
609 AM EDT Thu Aug 19 2021

The National Weather Service in Mount Holly has issued a

* Flood Warning for...
  South Central Mercer County in central New Jersey...
  Southeastern Bucks County in southeastern Pennsylvania...
  Northeastern Philadelphia County in southeastern Pennsylvania...

* Until 900 AM EDT.

* At 609 AM EDT, Doppler radar and automated rain gauges indicated 
  heavy rain fell across the warned area overnight. The rain has 
  ended, and conditions will continue to gradually improve. However, 
  some road closures remain in place and some small streams and 
  creeks may still be out of their banks. Residual flooding will 
  continue at least through mid-morning.

* Some locations that will experience 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.

&&

LAT...LON 3999 7510 3999 7514 4025 7485 4017 7465
      4017 7468 4018 7470 4018 7471 4017 7471
      4017 7470 4016 7471 4014 7474 4013 7476
      4012 7479 4013 7482 4010 7484 4009 7486
      4006 7496

$$

JEO
1 follow-up statement
175 
WGUS81 KPHI 191252
FLSPHI

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

NJC021-PAC017-101-191302-
/O.EXP.KPHI.FA.W.0016.000000T0000Z-210819T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Bucks PA-Philadelphia PA-
852 AM EDT Thu Aug 19 2021

...FLOOD WARNING WILL EXPIRE AT 9 AM EDT THIS MORNING FOR SOUTH 
CENTRAL MERCER, SOUTHEASTERN BUCKS, AND NORTHEASTERN PHILADELPHIA 
COUNTIES...

Flood waters have receded. The heavy rain has ended. 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 7468 4018 7470 4018 7471 4017 7471
      4017 7470 4016 7471 4014 7474 4013 7476
      4012 7479 4013 7482 4010 7484 4009 7486
      4006 7496

$$

BAH

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, 2:13 AM EDTFlash Flood WarningPHIBucks, Philadelphia4 hr
Aug 19, 4:33 AM EDTAreal Flood WarningPHIChester, Delaware4 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

Areal Flood Warnings in Pennsylvania, 2021Areal Flood Warnings in New Jersey, 2021Every areal 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.