Alert archive / New Jersey / Flood Watches in 2026

Flood Watch 5, NWS Philadelphia/Mount Holly

July 20, 2026New Castle County, Delaware; 9 counties in New Jersey; 5 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flood watch at Jul 20, 2026, 2:44 PM EDT for New Castle County, Delaware; 9 counties in New Jersey; 5 counties in Pennsylvania. It took effect at Jul 21, 2026, 6:00 AM EDT. It was in force for 16 hr.

The area

The counties it named.

The facts

Issued
Jul 20, 2026, 2:44 PM EDT (18:44 UTC)
In effect from
Jul 21, 2026, 6:00 AM EDT
Expired
Jul 21, 2026, 9:39 PM EDT
In force
16 hr
Issued by
NWS Philadelphia/Mount Holly
Flood severity
None

Counties New Castle County, DE, Burlington County, NJ, Camden County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Somerset County, NJ, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 53 km from the middle of the area, began a volume at 18:43 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, 6.7 hours before the alert went out and 194 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 2026-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2026-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 22 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1548 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
22 m²/s²
0-3 km storm-relative helicity
129 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

850 
WGUS61 KPHI 201844
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Mount Holly NJ
244 PM EDT Mon Jul 20 2026

DEZ001-NJZ008>010-012>015-017>019-PAZ070-071-101>106-211000-
/O.NEW.KPHI.FA.A.0005.260721T1000Z-260722T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-
Eastern Monmouth-Mercer-Gloucester-Camden-Northwestern Burlington-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Honey Brook, Wilmington, Doylestown,
Morristown, West Chester, Mount Holly, Perkasie, Somerville,
Norristown, Media, Morrisville, Sandy Hook, Cherry Hill,
Collegeville, Lansdale, Moorestown, Trenton, New Brunswick,
Kennett Square, Glassboro, Pottstown, Philadelphia, Flemington,
Chalfont, Camden, Oxford, and Freehold
244 PM EDT Mon Jul 20 2026

...FLOOD WATCH IN EFFECT FROM TUESDAY MORNING THROUGH LATE TUESDAY 
NIGHT...

* WHAT...Flash flooding caused by excessive rainfall is possible.

* WHERE...Portions of northern Delaware, including the following 
  area, New Castle, New Jersey, including the following areas, 
  Camden, Eastern Monmouth, Gloucester, Hunterdon, Mercer, 
  Middlesex, Morris, Northwestern Burlington, Somerset and Western 
  Monmouth, and southeast Pennsylvania, including the following 
  areas, Delaware, Eastern Chester, Eastern Montgomery, Lower Bucks, 
  Philadelphia, Upper Bucks, Western Chester and Western Montgomery.

* WHEN...From Tuesday morning through late Tuesday night.

* IMPACTS...Excessive runoff may result in flooding of rivers, 
  creeks, streams, and other low-lying and flood-prone locations. 
  Flooding may occur in poor drainage and urban areas.

* ADDITIONAL DETAILS...
  - Multiple rounds of heavy showers and thunderstorms are
    expected beginning Tuesday morning through Tuesday night.
    Rainfall rates of up to 2 inches per hour will be possible at
    times.
  - http://www.weather.gov/safety/flood

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

MJL
3 follow-up statements
508 
WGUS61 KPHI 210707
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
307 AM EDT Tue Jul 21 2026

DEZ001-NJZ008>010-012>015-017>019-PAZ070-071-101>106-212100-
/O.CON.KPHI.FA.A.0005.260721T1000Z-260722T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-
Eastern Monmouth-Mercer-Gloucester-Camden-Northwestern Burlington-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Chalfont, Glassboro, Kennett Square,
Doylestown, West Chester, Wilmington, Mount Holly, Flemington,
Oxford, Sandy Hook, Moorestown, Norristown, New Brunswick,
Lansdale, Perkasie, Pottstown, Honey Brook, Cherry Hill,
Philadelphia, Somerville, Camden, Trenton, Media, Morristown,
Collegeville, Freehold, and Morrisville
307 AM EDT Tue Jul 21 2026

...FLOOD WATCH REMAINS IN EFFECT THROUGH LATE TONIGHT...

* WHAT...Flash flooding caused by excessive rainfall continues to be 
  possible.

* WHERE...Portions of northern Delaware, including the following 
  area, New Castle, New Jersey, including the following areas, 
  Camden, Eastern Monmouth, Gloucester, Hunterdon, Mercer, 
  Middlesex, Morris, Northwestern Burlington, Somerset and Western 
  Monmouth, and southeast Pennsylvania, including the following 
  areas, Delaware, Eastern Chester, Eastern Montgomery, Lower Bucks, 
  Philadelphia, Upper Bucks, Western Chester and Western Montgomery.

* WHEN...Through late tonight.

* IMPACTS...Excessive runoff may result in flooding of rivers, 
  creeks, streams, and other low-lying and flood-prone locations. 
  Flooding may occur in poor drainage and urban areas.

* ADDITIONAL DETAILS...
  - Showers and thunderstorms will increase today into tonight,
    with the most widespread activity occurring this afternoon
    and this evening. Some heavy showers and thunderstorms will
    produce torrential rainfall, with 2 to 3 inches of rain per
    hour possible. The excessive rainfall within a short period
    of time, especially in urban areas, could lead to flash
    flooding.
  - http://www.weather.gov/safety/flood

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

MJL/Gorse
671 
WGUS61 KPHI 212046
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
446 PM EDT Tue Jul 21 2026

DEZ001-NJZ008>010-012>015-017>019-PAZ070-071-101>106-220600-
/O.CON.KPHI.FA.A.0005.000000T0000Z-260722T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-
Eastern Monmouth-Mercer-Gloucester-Camden-Northwestern Burlington-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of West Chester, Flemington, Moorestown,
Sandy Hook, Mount Holly, New Brunswick, Media, Lansdale,
Wilmington, Philadelphia, Honey Brook, Chalfont, Perkasie,
Doylestown, Morristown, Pottstown, Cherry Hill, Camden, Kennett
Square, Morrisville, Glassboro, Somerville, Oxford, Norristown,
Trenton, Collegeville, and Freehold
446 PM EDT Tue Jul 21 2026

...FLOOD WATCH REMAINS IN EFFECT UNTIL 2 AM EDT WEDNESDAY...

* WHAT...Flash flooding caused by excessive rainfall continues to be 
  possible.

* WHERE...Portions of northern Delaware, including the following 
  area, New Castle, New Jersey, including the following areas, 
  Camden, Eastern Monmouth, Gloucester, Hunterdon, Mercer, 
  Middlesex, Morris, Northwestern Burlington, Somerset and Western 
  Monmouth, and southeast Pennsylvania, including the following 
  areas, Delaware, Eastern Chester, Eastern Montgomery, Lower Bucks, 
  Philadelphia, Upper Bucks, Western Chester and Western Montgomery.

* WHEN...Until 2 AM EDT Wednesday.

* IMPACTS...Excessive runoff may result in flooding of rivers, 
  creeks, streams, and other low-lying and flood-prone locations. 
  Flooding may occur in poor drainage and urban areas.

* ADDITIONAL DETAILS...
  - Showers and thunderstorms will continue into tonight with the
    most widespread activity occurring through this evening. Some
    heavy showers and thunderstorms will produce torrential
    rainfall, with 2 to 3 inches of rain per hour possible. The
    excessive rainfall within a short period of time, especially
    in urban areas, could lead to flash flooding.
  - http://www.weather.gov/safety/flood

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

Hoeflich
256 
WGUS61 KPHI 220139
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
939 PM EDT Tue Jul 21 2026

DEZ001-NJZ008>010-012>015-017>019-PAZ070-071-101>106-220245-
/O.CAN.KPHI.FA.A.0005.000000T0000Z-260722T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Morris-Hunterdon-Somerset-Middlesex-Western Monmouth-
Eastern Monmouth-Mercer-Gloucester-Camden-Northwestern Burlington-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Mount Holly, Collegeville, Norristown,
Flemington, Freehold, New Brunswick, Camden, Cherry Hill,
Perkasie, Moorestown, Lansdale, Media, Morristown, Chalfont,
Morrisville, Trenton, Wilmington, Pottstown, Kennett Square,
Honey Brook, Oxford, Sandy Hook, Glassboro, West Chester,
Doylestown, Somerville, and Philadelphia
939 PM EDT Tue Jul 21 2026

...FLOOD WATCH IS CANCELLED...

The Flash Flood Watch is cancelled for portions of northern 
Delaware, including the following area, New Castle, New Jersey, 
including the following areas, Camden, Eastern Monmouth, Gloucester, 
Hunterdon, Mercer, Middlesex, Morris, Northwestern Burlington, 
Somerset and Western Monmouth, and southeast Pennsylvania, including 
the following areas, Delaware, Eastern Chester, Eastern Montgomery, 
Lower Bucks, Philadelphia, Upper Bucks, Western Chester and Western 
Montgomery.

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

$$

Fitzsimmons

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 1:06 AM EDTSmall Craft AdvisoryPHI71 hr

Nearby

Flood Watches in New Jersey, 2026Flood Watches in Pennsylvania, 2026Flood Watches in Delaware, 2026Every flood watch in 2026

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.