Alert archive / Pennsylvania / Areal Flood Warnings in 2021

Areal Flood Warning 34, NWS Philadelphia/Mount Holly

September 1, 20214 counties in Pennsylvania; Warren County, New Jersey

NWS Philadelphia/Mount Holly issued this areal flood warning at Sep 1, 2021, 10:47 PM EDT for 4 counties in Pennsylvania; Warren County, New Jersey. It was in force for 23 hr. 7 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
Sep 1, 2021, 10:47 PM EDT (02:47 UTC)
Expired
Sep 2, 2021, 10:16 PM EDT
In force
23 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Warren County, NJ, Bucks County, PA, Carbon County, PA, Lehigh County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 127 km from the middle of the area, began a volume at 02:49 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
Sep 1, 10:58 PM EDTFLASH FLOOD2 Sw Salisbury Twp, PASTATE ROUTE 145 CLOSED FROM FLOODING NORTH OF I-78. TIME BASED ON DISPATCH REPORT.
Sep 1, 11:26 PM EDTHEAVY RAIN 5.95Neffs, PASTORM TOTAL.
Sep 1, 11:50 PM EDTFLASH FLOOD2 S Hellertown, PALEITHSVILLE ROAD CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.
Sep 2, 12:30 AM EDTFLOOD1 Ne Fountain Hill, PATHE GAUGE ON THE LEHIGH RIVER AT BETHLEHEM (BETP1) REACHED FLOOD STAGE AT 1230 AM 9/2, CRESTING AT 19.53 FEET (MINOR FLOODING) AT 730 AM 9/2.
Sep 2, 4:30 AM EDTFLOOD1 Wsw Whitehall Twp, PATHE GAUGE ON JORDAN CREEK AT ALLENTOWN (ALNP1) REACHED FLOOD STAGE AT 430 AM 9/2, CRESTING AT 10.71 FEET (MODERATE FLOODING) AT 800 AM 9/2.
Sep 2, 6:45 AM EDTFLOODEaston, PATHE GAUGE ON THE DELAWARE RIVER AT EASTON (ESTN4) REACHED FLOOD STAGE AT 645 AM 9/2, CRESTING AT 25.73 FEET (MINOR FLOODING) AT 215 AM 9/2.
Sep 2, 7:45 AM EDTFLOOD3 W Holland Twp, NJTHE GAUGE ON THE DELAWARE RIVER AT RIEGELSVILLE (RGLN4) REACHED FLOOD STAGE AT 745 AM 9/2, CRESTING AT 24.92 FEET (MINOR FLOODING) AT 300 PM 9/2.

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, 2.8 hours before the alert went out and 225 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 2021-09-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 123 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 00:00Z on 2021-09-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 279 square meters per square second.19395878Sfc1 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
123 J/kg
Mixed-layer CIN
-47 J/kg
Mixed-layer LCL
512 m above ground
0-6 km bulk shear
53 kt
0-1 km storm-relative helicity
279 m²/s²
0-3 km storm-relative helicity
456 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

Open this sounding in Storm Lab

The text

As transmitted.

369 
WGUS41 KPHI 020247
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
1047 PM EDT Wed Sep 1 2021

NJC041-PAC017-025-077-095-021500-
/O.NEW.KPHI.FA.W.0034.210902T0247Z-210902T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Warren NJ-Bucks PA-Carbon PA-Lehigh PA-Northampton PA-
1047 PM EDT Wed Sep 1 2021

The National Weather Service in Mount Holly has issued a

* Flood Warning for...
  Southwestern Warren County in northwestern New Jersey...
  Lehigh County in eastern Pennsylvania...
  Northampton County in eastern Pennsylvania...
  Southeastern Carbon County in northeastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...

* Until 1100 AM EDT Thursday.

* At 1047 PM EDT, local law enforcement reported widespread flooding 
  in the warned area. Numerous road are closed, and several stream 
  and river gauges are in flood. Avoid unnecessary travel in the 
  warned area. Flooding is already occurring.

* Some locations that may experience flooding include...
  Allentown, Easton, Bethlehem, Forks, Emmaus, Northampton, Wilson, 
  Hellertown, Nazareth, Slatington, Bath, and Walnutport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4078 7569 4082 7548 4083 7539 4078 7516
      4058 7519 4042 7548 4068 7589 4071 7581

$$

CMS
5 follow-up statements
396 
WGUS41 KPHI 021444
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
1044 AM EDT Thu Sep 2 2021

NJC041-PAC017-025-077-095-021900-
/O.EXT.KPHI.FA.W.0034.000000T0000Z-210902T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Warren NJ-Bucks PA-Carbon PA-Lehigh PA-Northampton PA-
1044 AM EDT Thu Sep 2 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  Southwestern Warren County in northwestern New Jersey...
  Lehigh County in eastern Pennsylvania...
  Northampton County in eastern Pennsylvania...
  Southeastern Carbon County in northeastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...

* Until 300 PM EDT.

* At 1044 AM EDT, local law enforcement reported flooding in the 
  warned area. Flooding is already occurring.

* Some locations that may experience flooding include...
  Allentown, Easton, Bethlehem, Forks, Emmaus, Northampton, Wilson, 
  Hellertown, Nazareth, Slatington, Bath, and Walnutport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4078 7569 4082 7548 4083 7539 4078 7516
      4058 7519 4042 7548 4068 7589 4071 7581

$$

Kruzdlo
108 
WGUS81 KPHI 021837
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
237 PM EDT Thu Sep 2 2021

NJC041-PAC017-025-095-021847-
/O.CAN.KPHI.FA.W.0034.000000T0000Z-210902T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Warren NJ-Bucks PA-Carbon PA-Northampton PA-
237 PM EDT Thu Sep 2 2021

...FLOOD WARNING IS CANCELLED FOR SOUTHWESTERN WARREN, NORTHAMPTON, 
SOUTHEASTERN CARBON, AND NORTHWESTERN BUCKS COUNTIES...

This flood warning will be cancelled for portions of Warren, 
Northampton, southeastern Carbon, and Bucks counties. Additional 
flood warnings remain in effect across the region.

LAT...LON 4062 7559 4067 7549 4067 7548 4066 7548
      4066 7546 4067 7545 4067 7543 4066 7542
      4057 7543 4053 7555 4058 7565 4062 7562

$$

PAC077-021900-
/O.CON.KPHI.FA.W.0034.000000T0000Z-210902T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
237 PM EDT Thu Sep 2 2021

...FLOOD WARNING REMAINS IN EFFECT UNTIL 3 PM EDT THIS AFTERNOON FOR 
EAST CENTRAL LEHIGH COUNTY...

At 237 PM EDT, gauge reports indicated flooding was ongoing.

For Little Lehigh at Allentown:
At 1:45pm the stage was 6.21 feet.
Flood Stage is 5 feet.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4062 7559 4067 7549 4067 7548 4066 7548
      4066 7546 4067 7545 4067 7543 4066 7542
      4057 7543 4053 7555 4058 7565 4062 7562

$$

Kruzdlo
390 
WGUS41 KPHI 021839
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
239 PM EDT Thu Sep 2 2021

PAC077-030100-
/O.EXT.KPHI.FA.W.0034.000000T0000Z-210903T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
239 PM EDT Thu Sep 2 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  East Central Lehigh County in eastern Pennsylvania...

* Until 900 PM EDT Thursday.

* At 239 PM EDT, gauge reports indicated flooding was ongoing.

* For Little Lehigh at Allentown:
  At 2:30pm the stage was 5.92 feet.
  Flood Stage is 5 feet.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4062 7559 4067 7549 4067 7548 4066 7548
      4066 7546 4067 7545 4067 7543 4066 7542
      4057 7543 4053 7555 4058 7565 4062 7562

$$

Kruzdlo
762 
WGUS41 KPHI 022101
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
501 PM EDT Thu Sep 2 2021

PAC077-030300-
/O.EXT.KPHI.FA.W.0034.000000T0000Z-210903T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
501 PM EDT Thu Sep 2 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  East Central Lehigh County in eastern Pennsylvania...

* Until 1100 PM EDT.

* At 501 PM EDT, gauge reports indicated flooding was ongoing.

* For Little Lehigh at Allentown:
  At 4:30pm the stage was 5.17 feet.
  Flood Stage is 5 feet.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4062 7559 4067 7549 4067 7548 4066 7548
      4066 7546 4067 7545 4067 7543 4066 7542
      4057 7543 4053 7555 4058 7565 4062 7562

$$

Kruzdlo
845 
WGUS81 KPHI 030216
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
1016 PM EDT Thu Sep 2 2021

PAC077-030226-
/O.CAN.KPHI.FA.W.0034.000000T0000Z-210903T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
1016 PM EDT Thu Sep 2 2021

...FLOOD WARNING IS CANCELLED FOR EAST CENTRAL LEHIGH COUNTY...

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

LAT...LON 4062 7559 4067 7549 4067 7548 4066 7548
      4066 7546 4067 7545 4067 7543 4066 7542
      4057 7543 4053 7555 4058 7565 4062 7562

$$

SFJ

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 1, 8:29 PM EDTRiver Flood WarningPHILehigh10 hr
Sep 1, 9:47 PM EDTRiver Flood WarningPHIBerks18 hr
Sep 1, 10:24 PM EDTFlash Flood WarningPHIBucks, Philadelphia4 hr
Sep 1, 10:29 PM EDTRiver Flood WarningPHIBucks49 hr
Sep 1, 10:32 PM EDTRiver Flood WarningPHIBucks31 hr
Sep 1, 10:42 PM EDTAreal Flood WarningPHIBerks, Bucks, Montgomery12 hr
Sep 1, 10:52 PM EDTAreal Flood WarningPHIBucks12 hr
Sep 1, 11:38 PM EDTAreal Flood WarningPHIBerks, Chester, Delaware, Montgomery10 hr
Sep 2, 12:01 AM EDTAreal Flood WarningPHIMonroe, Northampton40 hr
Sep 2, 2:23 AM EDTAreal Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia9 hr
Sep 2, 2:29 AM EDTAreal Flood WarningPHIBucks, Philadelphia5 hr
Sep 2, 2:41 AM EDTAreal Flood WarningPHIBucks14 hr
Sep 2, 3:52 AM EDTAreal Flood WarningPHIBucks8 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIBucks37 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHINorthampton37 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIBucks37 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIBucks33 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIBucks34 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIMonroe, Northampton5 hr
Sep 2, 5:02 AM EDTRiver Flood WarningPHILehigh11 hr
Sep 2, 6:05 AM EDTCoastal Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia6 hr
Sep 2, 6:44 PM EDTCoastal Flood AdvisoryPHIBucks, Delaware, Philadelphia7 hr
Sep 1, 8:02 PM EDTFlash Flood Warning EmergencyCatastrophic damage threatPHIMiddlesex, Morris, Somerset5 hr
Sep 1, 9:01 PM EDTFlash Flood WarningPHIBurlington, Mercer, Middlesex, Monmouth, Ocean5 hr
Sep 1, 9:43 PM EDTRiver Flood WarningPHIMercer33 hr
Sep 1, 10:05 PM EDTFlash Flood Warning Considerable damage threatPHIMorris, Somerset4 hr
Sep 1, 10:23 PM EDTCoastal Flood StatementPHIOcean13 hr
Sep 1, 10:35 PM EDTRiver Flood WarningPHIBergen, Morris, Passaic30 hr
Sep 1, 10:37 PM EDTRiver Flood WarningPHIMorris, Passaic41 hr
Sep 1, 10:38 PM EDTRiver Flood WarningPHIMorris, Somerset21 days
Sep 2, 12:28 AM EDTAreal Flood AdvisoryPHIAtlantic, Burlington, Camden, Gloucester3 hr
Sep 2, 12:31 AM EDTAreal Flood AdvisoryPHIMonmouth, Ocean2 hr
Sep 2, 1:38 AM EDTAreal Flood WarningPHIBurlington, Mercer, Middlesex, Monmouth, Ocean4 hr
Sep 2, 1:52 AM EDTAreal Flood WarningPHIMorris, Somerset13 hr
Sep 2, 3:53 AM EDTAreal Flood WarningPHIHunterdon, Mercer, Middlesex, Morris, Somerset8 hr
Sep 2, 4:00 AM EDTRiver Flood WarningPHIMorris48 hr
Sep 2, 1:20 PM EDTAreal Flood WarningPHIMiddlesex21 hr

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.