Alert archive / New Jersey / Flash Flood Watches in 2021

Flash Flood Watch 5, NWS Philadelphia/Mount Holly

July 16, 202110 counties in Pennsylvania; 14 counties in New Jersey; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood watch at Jul 16, 2021, 3:17 PM EDT for 10 counties in Pennsylvania; 14 counties in New Jersey; New Castle County, Delaware. It took effect at Jul 17, 2021, 2:00 PM EDT. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued
Jul 16, 2021, 3:17 PM EDT (19:17 UTC)
In effect from
Jul 17, 2021, 2:00 PM EDT
Expired
Jul 18, 2021, 1:49 AM EDT
In force
12 hr
Issued by
NWS Philadelphia/Mount Holly
Flood severity
None
All 25 counties

New Castle County, DE, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Delaware County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 66 km from the middle of the area, began a volume at 19:18 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 12:00Z, 7.3 hours before the alert went out and 196 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 12:00Z on 2021-07-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1044 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 12:00Z on 2021-07-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 108 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
1044 J/kg
Mixed-layer CIN
-56 J/kg
Mixed-layer LCL
994 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
108 m²/s²
0-3 km storm-relative helicity
105 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

498 
WGUS61 KPHI 161917
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Mount Holly NJ
317 PM EDT Fri Jul 16 2021

DEZ001-NJZ001-007>010-012>020-025>027-PAZ054-055-060>062-070-071-
101>106-171215-
/O.NEW.KPHI.FF.A.0005.210717T1800Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Western
Monmouth-Eastern Monmouth-Mercer-Salem-Gloucester-Camden-
Northwestern Burlington-Ocean-Coastal Atlantic-Coastal Ocean-
Southeastern Burlington-Carbon-Monroe-Berks-Lehigh-Northampton-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Glassboro, Jim Thorpe, Flemington, Atlantic 
City, Easton, Philadelphia, Doylestown, Chalfont, Morristown, 
Jackson, Pennsville, Reading, Lansdale, Norristown, Honey Brook, 
Mount Holly, Cherry Hill, Moorestown, Freehold, Pottstown, 
Allentown, Oxford, Wharton State Forest, Kennett Square, Sandy Hook, 
West Chester, Morrisville, Wilmington, New Brunswick, Media, 
Trenton, Newton, Washington, Collegeville, Long Beach Island, 
Camden, Bethlehem, Stroudsburg, Perkasie, and Somerville
317 PM EDT Fri Jul 16 2021

...FLASH FLOOD WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH LATE 
SATURDAY NIGHT...

The National Weather Service in Mount Holly has issued a

* Flash Flood Watch for portions of northern Delaware...New Jersey...
  and Pennsylvania...including the following areas...in northern 
  Delaware...New Castle. In New Jersey...Camden, Coastal Atlantic, 
  Coastal Ocean, Eastern Monmouth, Gloucester, Hunterdon, Mercer, 
  Middlesex, Morris, Northwestern Burlington, Ocean, Salem, 
  Somerset, Southeastern Burlington, Sussex, Warren, and Western 
  Monmouth. In Pennsylvania...Berks, Carbon, Delaware, Eastern 
  Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, 
  Northampton, Philadelphia, Upper Bucks, Western Chester, and 
  Western Montgomery.

* From Saturday afternoon through late Saturday night.

* Thunderstorms with locally heavy rain are expected to affect 
  eastern Pennsylvania, northern Delaware and New Jersey from 
  Saturday afternoon into Saturday evening. Rainfall totals of 1 to 
  2 inches are anticipated in a short amount of time with local 
  amounts up to 3 to 5 inches possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Iovino
5 follow-up statements
694 
WGUS61 KPHI 170916
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
516 AM EDT Sat Jul 17 2021

DEZ001-NJZ001-007>010-012>020-025>027-PAZ054-055-060>062-070-071-
101>106-172130-
/O.CON.KPHI.FF.A.0005.210717T1800Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Western
Monmouth-Eastern Monmouth-Mercer-Salem-Gloucester-Camden-
Northwestern Burlington-Ocean-Coastal Atlantic-Coastal Ocean-
Southeastern Burlington-Carbon-Monroe-Berks-Lehigh-Northampton-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Glassboro, Jim Thorpe, Flemington, Atlantic 
City, Easton, Philadelphia, Doylestown, Chalfont, Morristown, 
Jackson, Pennsville, Reading, Lansdale, Norristown, Honey Brook, 
Mount Holly, Cherry Hill, Moorestown, Freehold, Pottstown, 
Allentown, Oxford, Wharton State Forest, Kennett Square, Sandy Hook, 
West Chester, Morrisville, Wilmington, New Brunswick, Media, 
Trenton, Newton, Washington, Collegeville, Long Beach Island, 
Camden, Bethlehem, Stroudsburg, Perkasie, and Somerville
516 AM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 2 PM EDT THIS AFTERNOON 
THROUGH LATE TONIGHT...

The Flash Flood Watch continues for

* Portions of northern Delaware...New Jersey...and Pennsylvania...
  including the following areas...in northern Delaware...New Castle. 
  In New Jersey...Camden, Coastal Atlantic, Coastal Ocean, Eastern 
  Monmouth, Gloucester, Hunterdon, Mercer, Middlesex, Morris, 
  Northwestern Burlington, Ocean, Salem, Somerset, Southeastern 
  Burlington, Sussex, Warren, and Western Monmouth. In 
  Pennsylvania...Berks, Carbon, Delaware, Eastern Chester, Eastern 
  Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, 
  Philadelphia, Upper Bucks, Western Chester, and Western Montgomery.

* From 2 PM EDT this afternoon through late tonight.

* Thunderstorms with locally heavy rain are expected to affect 
  eastern Pennsylvania, northern Delaware and New Jersey from 
  Saturday afternoon into Saturday evening. Rainfall totals of 1 to 
  2 inches are anticipated in a short amount of time with local 
  amounts up to 3 to 5 inches possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Staarmann
457 
WGUS61 KPHI 171904
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
304 PM EDT Sat Jul 17 2021

DEZ001-NJZ001-007>010-012>020-025>027-PAZ054-055-060>062-070-071-
101>106-180600-
/O.CON.KPHI.FF.A.0005.000000T0000Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Western
Monmouth-Eastern Monmouth-Mercer-Salem-Gloucester-Camden-
Northwestern Burlington-Ocean-Coastal Atlantic-Coastal Ocean-
Southeastern Burlington-Carbon-Monroe-Berks-Lehigh-Northampton-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Glassboro, Jim Thorpe, Flemington, Atlantic 
City, Easton, Philadelphia, Doylestown, Chalfont, Morristown, 
Jackson, Pennsville, Reading, Lansdale, Norristown, Honey Brook, 
Mount Holly, Cherry Hill, Moorestown, Freehold, Pottstown, 
Allentown, Oxford, Wharton State Forest, Kennett Square, Sandy Hook, 
West Chester, Morrisville, Wilmington, New Brunswick, Media, 
Trenton, Newton, Washington, Collegeville, Long Beach Island, 
Camden, Bethlehem, Stroudsburg, Perkasie, and Somerville
304 PM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 2 AM EDT SUNDAY...

The Flash Flood Watch continues for

* Portions of northern Delaware...New Jersey...and Pennsylvania...
  including the following areas...in northern Delaware...New Castle. 
  In New Jersey...Camden, Coastal Atlantic, Coastal Ocean, Eastern 
  Monmouth, Gloucester, Hunterdon, Mercer, Middlesex, Morris, 
  Northwestern Burlington, Ocean, Salem, Somerset, Southeastern 
  Burlington, Sussex, Warren, and Western Monmouth. In 
  Pennsylvania...Berks, Carbon, Delaware, Eastern Chester, Eastern 
  Montgomery, Lehigh, Lower Bucks, Monroe, Northampton, 
  Philadelphia, Upper Bucks, Western Chester, and Western Montgomery.

* Until 2 AM EDT Sunday.

* Thunderstorms with locally heavy rain are expected to affect 
  eastern Pennsylvania, northern Delaware and New Jersey from this 
  afternoon into tonight. Rainfall totals of 1 to 2 inches are 
  anticipated in a short amount of time with local amounts up to 3 
  to 5 inches possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Iovino
653 
WGUS61 KPHI 180257
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
1057 PM EDT Sat Jul 17 2021

NJZ001-007-PAZ054-055-060>062-101-102-180400-
/O.CAN.KPHI.FF.A.0005.000000T0000Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex-Warren-Carbon-Monroe-Berks-Lehigh-Northampton-Western Chester-
Eastern Chester-
Including the cities of Honey Brook, Jim Thorpe, West Chester, 
Allentown, Newton, Washington, Bethlehem, Stroudsburg, Oxford, 
Reading, Kennett Square, and Easton
1057 PM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH IS CANCELED...

The Flash Flood Watch for portions of northern New Jersey...and 
Pennsylvania...including the following areas...in northern New 
Jersey...Sussex and Warren. In Pennsylvania...Berks, Carbon, Eastern 
Chester, Lehigh, Monroe, Northampton, and Western Chester has been 
cancelled.

The Flood Watch is canceled.

$$

DEZ001-NJZ008>010-012>020-025>027-PAZ070-071-103>106-180600-
/O.CON.KPHI.FF.A.0005.000000T0000Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-
Eastern Monmouth-Mercer-Salem-Gloucester-Camden-Northwestern
Burlington-Ocean-Coastal Atlantic-Coastal Ocean-Southeastern
Burlington-Delaware-Philadelphia-Western Montgomery-Eastern
Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Glassboro, Jackson, Flemington, Media, 
Philadelphia, Doylestown, Chalfont, Morristown, Pennsville, 
Lansdale, Norristown, Mount Holly, Cherry Hill, Moorestown, 
Freehold, Pottstown, Sandy Hook, Morrisville, Wilmington, New 
Brunswick, Trenton, Wharton State Forest, Atlantic City, 
Collegeville, Long Beach Island, Camden, Perkasie, and Somerville
1057 PM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 2 AM EDT SUNDAY...

The Flash Flood Watch continues for

* Portions of northern Delaware...New Jersey...and southeast 
  Pennsylvania...including the following areas...in northern 
  Delaware...New Castle. In New Jersey...Camden, Coastal Atlantic, 
  Coastal Ocean, Eastern Monmouth, Gloucester, Hunterdon, Mercer, 
  Middlesex, Morris, Northwestern Burlington, Ocean, Salem, 
  Somerset, Southeastern Burlington, and Western Monmouth. In 
  southeast Pennsylvania...Delaware, Eastern Montgomery, Lower 
  Bucks, Philadelphia, Upper Bucks, and Western Montgomery.

* Until 2 AM EDT Sunday.

* Thunderstorms with locally heavy rain are expected to affect 
  eastern Pennsylvania, northern Delaware and New Jersey through 
  tonight. Rainfall totals of 1 to 2 inches are anticipated in a 
  short amount of time with local amounts up to 4 to 6 inches 
  possible.

$$

BAH
612 
WGUS61 KPHI 180358
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
1158 PM EDT Sat Jul 17 2021

DEZ001-NJZ016-017-PAZ070-071-103>106-180500-
/O.CAN.KPHI.FF.A.0005.000000T0000Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Salem-Gloucester-Delaware-Philadelphia-Western Montgomery-
Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Glassboro, Chalfont, Media, Morrisville, 
Wilmington, Collegeville, Doylestown, Philadelphia, Pennsville, 
Pottstown, Lansdale, Perkasie, and Norristown
1158 PM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH IS CANCELED...

The Flash Flood Watch for portions of northern Delaware...southern 
New Jersey...and southeast Pennsylvania...including the following 
areas...in northern Delaware...New Castle. In southern New Jersey...
Gloucester and Salem. In southeast Pennsylvania...Delaware, Eastern 
Montgomery, Lower Bucks, Philadelphia, Upper Bucks, and Western 
Montgomery has been cancelled.

The Flood Watch is canceled.

$$

NJZ008>010-012>015-018>020-025>027-180600-
/O.CON.KPHI.FF.A.0005.000000T0000Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-Eastern
Monmouth-Mercer-Camden-Northwestern Burlington-Ocean-Coastal
Atlantic-Coastal Ocean-Southeastern Burlington-
Including the cities of Trenton, Mount Holly, Flemington, Cherry 
Hill, Moorestown, Wharton State Forest, Atlantic City, Freehold, 
Long Beach Island, Morristown, Camden, Jackson, Somerville, New 
Brunswick, and Sandy Hook
1158 PM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 2 AM EDT SUNDAY...

The Flash Flood Watch continues for

* Portions of central New Jersey...northern New Jersey...northwest 
  New Jersey...and southern New Jersey...including the following 
  areas...in central New Jersey...Eastern Monmouth, Mercer, and 
  Western Monmouth. In northern New Jersey...Middlesex, Morris, and 
  Somerset. In northwest New Jersey...Hunterdon. In southern New 
  Jersey...Camden, Coastal Atlantic, Coastal Ocean, Northwestern 
  Burlington, Ocean, and Southeastern Burlington.

* Until 2 AM EDT Sunday.

* Thunderstorms with locally heavy rain are expected to affect New 
  Jersey through tonight. Rainfall totals of 1 to 2 inches are 
  anticipated in a short amount of time with local amounts up to 4 
  to 6 inches possible.

$$

BAH
811 
WGUS61 KPHI 180549
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
149 AM EDT Sun Jul 18 2021

NJZ008>010-012>015-018>020-025>027-180700-
/O.CAN.KPHI.FF.A.0005.000000T0000Z-210718T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-Eastern
Monmouth-Mercer-Camden-Northwestern Burlington-Ocean-Coastal
Atlantic-Coastal Ocean-Southeastern Burlington-
Including the cities of Trenton, Mount Holly, Flemington, Cherry 
Hill, Moorestown, Wharton State Forest, Atlantic City, Freehold, 
Long Beach Island, Morristown, Camden, Jackson, Somerville, New 
Brunswick, and Sandy Hook
149 AM EDT Sun Jul 18 2021

...FLASH FLOOD WATCH IS CANCELED...

The Flash Flood Watch for portions of central New Jersey...northern 
New Jersey...northwest New Jersey...and southern New Jersey...
including the following areas...in central New Jersey...Eastern 
Monmouth, Mercer, and Western Monmouth. In northern New Jersey...
Middlesex, Morris, and Somerset. In northwest New Jersey...
Hunterdon. In southern New Jersey...Camden, Coastal Atlantic, 
Coastal Ocean, Northwestern Burlington, Ocean, and Southeastern 
Burlington has been cancelled.

The Flash Flood Watch is canceled. Flooding is no longer expected to 
pose a threat. Please continue to heed remaining road closures.

$$

BAH

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 16, 5:07 PM EDTSpecial Weather StatementPHICarbon23 min
Jul 16, 5:21 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton39 min
Jul 16, 5:25 PM EDTSpecial Weather StatementPHIMonroe35 min
Jul 16, 5:34 PM EDTAreal Flood AdvisoryPHICarbon, Lehigh, Monroe, Northampton112 min
Jul 16, 5:38 PM EDTSevere Thunderstorm WarningPHIMonroe20 min
Jul 16, 7:42 PM EDTSpecial Weather StatementPHIBerks33 min
Jul 16, 2:55 PM EDTAreal Flood AdvisoryPHISussex4 hr
Jul 16, 5:01 PM EDTAreal Flood AdvisoryPHISussex2 hr
Jul 16, 5:21 PM EDTFlash Flood WarningPHISussex2 hr
Jul 16, 5:29 PM EDTSevere Thunderstorm WarningPHISussex46 min
Jul 16, 6:10 PM EDTSpecial Weather StatementPHIWarren35 min
Jul 16, 6:14 PM EDTSpecial Weather StatementPHISussex31 min
Jul 16, 6:27 PM EDTAreal Flood AdvisoryPHISussex59 min
Jul 16, 6:46 PM EDTSpecial Weather StatementPHIWarren29 min
Jul 16, 7:10 PM EDTSpecial Weather StatementPHIWarren35 min

Nearby

Flash Flood Watches in New Jersey, 2021Flash Flood Watches in Pennsylvania, 2021Flash Flood Watches in Delaware, 2021Every flash flood watch 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.