Alert archive / Pennsylvania / Flood Watches in 2020

Flood Watch 4, NWS Philadelphia/Mount Holly

December 22, 20207 counties in New Jersey; 10 counties in Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this flood watch at Dec 22, 2020, 3:22 PM EST for 7 counties in New Jersey; 10 counties in Pennsylvania; New Castle County, Delaware. It took effect at Dec 24, 2020, 4:00 PM EST. It was in force for 18 hr.

The area

The counties it named.

The facts

Issued
Dec 22, 2020, 3:22 PM EST (20:22 UTC)
In effect from
Dec 24, 2020, 4:00 PM EST
Expired
Dec 25, 2020, 9:36 AM EST
In force
18 hr
Issued by
NWS Philadelphia/Mount Holly
Flood severity
None

Counties New Castle County, DE, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris 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), 87 km from the middle of the area, began a volume at 20:24 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, 8.4 hours before the alert went out and 200 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 2020-12-22Temperature 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 2020-12-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 18 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
790 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
18 m²/s²
0-3 km storm-relative helicity
10 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

406 
WGUS61 KPHI 222022
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Mount Holly NJ
322 PM EST Tue Dec 22 2020

.Heavy rain may fall on a deep primed snowpack leading to the melt 
increasing. Flows in rivers may increase quickly and reach critical 
levels.

NJZ001-007-PAZ054-055-060>062-231100-
/O.NEW.KPHI.FA.A.0004.201224T2300Z-201225T1100Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex-Warren-Carbon-Monroe-Berks-Lehigh-Northampton-
Including the cities of Jim Thorpe, Allentown, Newton, Washington, 
Bethlehem, Stroudsburg, Reading, and Easton
322 PM EST Tue Dec 22 2020

...FLOOD WATCH IN EFFECT FROM THURSDAY EVENING THROUGH LATE THURSDAY 
NIGHT...

The National Weather Service in Mount Holly has issued a

* 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, 
  Lehigh, Monroe, and Northampton.

* From Thursday evening through late Thursday night

* Heavy rain will move into the region Thursday night, with between 
  1 and 2 inches of rain over the region and as much as 2 to 3 
  inches of rain over the southern Poconos.

* The heaviest rain will fall over snowpack with as much as an inch 
  of liquid equivalent rainfall, leading to rapid melting of the 
  snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away or be swept away. River banks and culverts can become 
unstable and unsafe.

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

MPS
7 follow-up statements
013 
WGUS61 KPHI 230928
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Mount Holly NJ
428 AM EST Wed Dec 23 2020

.Heavy rain will fall on a deep primed snowpack leading to the melt 
increasing. Flows in rivers may increase quickly and reach critical 
levels.

NJZ008-009-PAZ101>103-105-232100-
/O.EXB.KPHI.FA.A.0004.201224T2100Z-201225T1500Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris-Hunterdon-Western Chester-Eastern Chester-Western Montgomery-
Upper Bucks-
Including the cities of Chalfont, Flemington, West Chester, 
Collegeville, Pottstown, Morristown, Oxford, Perkasie, Honey Brook, 
and Kennett Square
428 AM EST Wed Dec 23 2020

...FLOOD WATCH IN EFFECT FROM THURSDAY AFTERNOON THROUGH FRIDAY 
MORNING...

The National Weather Service in Mount Holly has expanded the

* Flood Watch to include portions of New Jersey...and southeast 
  Pennsylvania...including the following areas...in New Jersey...
  Hunterdon and Morris. In southeast Pennsylvania...Eastern Chester, 
  Upper Bucks, Western Chester, and Western Montgomery.

* From Thursday afternoon through Friday morning

* Heavy rain will move into the region Thursday night, with between 
  1 and 2 inches of rain over the region and as much as 2 to 3 
  inches of rain over the southern Poconos.

* The heaviest rain will fall over snowpack with as much as an inch 
  of liquid equivalent rainfall, leading to rapid melting of the 
  snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

NJZ001-007-PAZ054-055-060>062-232100-
/O.EXT.KPHI.FA.A.0004.201224T2100Z-201225T1500Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex-Warren-Carbon-Monroe-Berks-Lehigh-Northampton-
Including the cities of Jim Thorpe, Allentown, Newton, Washington, 
Bethlehem, Stroudsburg, Reading, and Easton
428 AM EST Wed Dec 23 2020

...FLOOD WATCH NOW IN EFFECT FROM THURSDAY AFTERNOON THROUGH FRIDAY 
MORNING...

The Flood Watch is now in effect for

* Portions of northern New Jersey...and Pennsylvania...including the 
  following areas...in northern New Jersey...Sussex and Warren. In 
  Pennsylvania...Berks, Carbon, Lehigh, Monroe, and Northampton.

* From Thursday afternoon through Friday morning

* Heavy rain will move into the region Thursday night, with between 
  1 and 2 inches of rain over the region and as much as 2 to 3 
  inches of rain over the southern Poconos.

* The heaviest rain will fall over snowpack with as much as an inch 
  of liquid equivalent rainfall, leading to rapid melting of the 
  snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

Staarmann
839 
WGUS61 KPHI 232035
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
335 PM EST Wed Dec 23 2020

.Heavy rain may fall on a deep primed snowpack leading to the melt 
increasing. Flows in Rivers may increase quickly and reach critical 
levels.

NJZ001-007>009-PAZ054-055-060>062-101>103-105-241100-
/O.CON.KPHI.FA.A.0004.201224T2100Z-201225T1500Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex-Warren-Morris-Hunterdon-Carbon-Monroe-Berks-Lehigh-
Northampton-Western Chester-Eastern Chester-Western Montgomery-Upper
Bucks-
Including the cities of Chalfont, Honey Brook, Jim Thorpe, 
Flemington, West Chester, Allentown, Newton, Washington, 
Collegeville, Pottstown, Morristown, Bethlehem, Stroudsburg, Oxford, 
Perkasie, Reading, Kennett Square, and Easton
335 PM EST Wed Dec 23 2020

...FLOOD WATCH REMAINS IN EFFECT FROM THURSDAY AFTERNOON THROUGH 
FRIDAY MORNING...

The Flood Watch continues for

* Portions of New Jersey...and Pennsylvania...including the 
  following areas...in New Jersey...Hunterdon, Morris, Sussex, and 
  Warren. In Pennsylvania...Berks, Carbon, Eastern Chester, Lehigh, 
  Monroe, Northampton, Upper Bucks, Western Chester, and Western 
  Montgomery.

* From Thursday afternoon through Friday morning

* Heavy rain will move into the region late Thursday and Thursday 
  night, with between 1 and 2 inches of rain over the region and as 
  much as 3 to 4 inches of rain over the southern Poconos.

* The heaviest rain will fall over snowpack with as much as an inch 
  of liquid equivalent rainfall, leading to rapid melting of the 
  snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

MPS
899 
WGUS61 KPHI 240828
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Mount Holly NJ
328 AM EST Thu Dec 24 2020

.Heavy rain may fall on a deep primed snowpack leading to the melt 
increasing. Flows in Rivers may increase quickly and reach critical 
levels.

DEZ001-NJZ010-012-015-PAZ070-071-104-106-241630-
/O.EXB.KPHI.FA.A.0004.201224T2100Z-201225T1700Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Somerset-Middlesex-Mercer-Delaware-Philadelphia-Eastern
Montgomery-Lower Bucks-
Including the cities of Trenton, Lansdale, Media, Morrisville, 
Wilmington, Philadelphia, Doylestown, Somerville, New Brunswick, and 
Norristown
328 AM EST Thu Dec 24 2020

...FLOOD WATCH IN EFFECT FROM THIS AFTERNOON THROUGH FRIDAY 
MORNING...

The National Weather Service in Mount Holly has expanded the

* Flood Watch to include portions of northern Delaware...New 
  Jersey...and southeast Pennsylvania...including the following 
  areas...in northern Delaware...New Castle. In New Jersey...Mercer, 
  Middlesex, and Somerset. In southeast Pennsylvania...Delaware, 
  Eastern Montgomery, Lower Bucks, and Philadelphia.

* From this afternoon through Friday morning

* Heavy rain will move into the region late Thursday and Thursday 
  night, with between 1 and 3 inches of rain over the region and as 
  much as 3 to 4 inches of rain over the southern Poconos.

* Excessive rainfall and snowmelt will result in rises on rivers and 
  streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

NJZ001-007>009-PAZ054-055-060>062-101>103-105-241630-
/O.EXT.KPHI.FA.A.0004.201224T2100Z-201225T1700Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex-Warren-Morris-Hunterdon-Carbon-Monroe-Berks-Lehigh-
Northampton-Western Chester-Eastern Chester-Western Montgomery-Upper
Bucks-
Including the cities of Chalfont, Honey Brook, Jim Thorpe, 
Flemington, West Chester, Allentown, Newton, Washington, 
Collegeville, Pottstown, Morristown, Bethlehem, Stroudsburg, Oxford, 
Perkasie, Reading, Kennett Square, and Easton
328 AM EST Thu Dec 24 2020

...FLOOD WATCH NOW IN EFFECT FROM THIS AFTERNOON THROUGH FRIDAY 
MORNING...

The Flood Watch is now in effect for

* Portions of New Jersey...and Pennsylvania...including the 
  following areas...in New Jersey...Hunterdon, Morris, Sussex, and 
  Warren. In Pennsylvania...Berks, Carbon, Eastern Chester, Lehigh, 
  Monroe, Northampton, Upper Bucks, Western Chester, and Western 
  Montgomery.

* From this afternoon through Friday morning

* Heavy rain will move into the region late Thursday and Thursday 
  night, with between 1 and 3 inches of rain over the region and as 
  much as 3 to 4 inches of rain over the southern Poconos.

* Excessive rainfall and snowmelt will result in rises on rivers and 
  streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

Staarmann
072 
WGUS61 KPHI 241557
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
1057 AM EST Thu Dec 24 2020

.Heavy rain may fall on a deep primed snowpack leading to the melt 
increasing. Flows in Rivers may increase quickly and reach critical 
levels.

DEZ001-NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-
250400-
/O.CON.KPHI.FA.A.0004.201224T2100Z-201225T1700Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-
Carbon-Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western
Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper
Bucks-Lower Bucks-
Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, 
Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, 
Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West 
Chester, Morrisville, Wilmington, New Brunswick, Trenton, Newton, 
Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and 
Somerville
1057 AM EST Thu Dec 24 2020

...FLOOD WATCH REMAINS IN EFFECT FROM 4 PM EST THIS AFTERNOON 
THROUGH FRIDAY MORNING...

The Flood Watch continues for

* Portions of northern Delaware...New Jersey...and Pennsylvania...
  including the following areas...in northern Delaware...New Castle. 
  In New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, 
  Sussex, and Warren. In Pennsylvania...Berks, Carbon, Delaware, 
  Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, 
  Northampton, Philadelphia, Upper Bucks, Western Chester, and 
  Western Montgomery.

* From 4 PM EST this afternoon through Friday morning

* Heavy rain will move into the region late Thursday and Thursday 
  night, with between 1 and 3 inches of rain over the region and as 
  much as 3 to 4 inches of rain over the southern Poconos.

* Excessive rainfall and snowmelt will result in rises on rivers and 
  streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

MPS
911 
WGUS61 KPHI 242016
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
316 PM EST Thu Dec 24 2020

.Heavy rain may fall on a deep primed snowpack leading to the melt 
increasing. Flows in Rivers may increase quickly and reach critical 
levels.

DEZ001-NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-
250830-
/O.CON.KPHI.FA.A.0004.201224T2100Z-201225T1700Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-
Carbon-Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western
Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper
Bucks-Lower Bucks-
Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, 
Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, 
Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West 
Chester, Morrisville, Wilmington, New Brunswick, Trenton, Newton, 
Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and 
Somerville
316 PM EST Thu Dec 24 2020

...FLOOD WATCH REMAINS IN EFFECT THROUGH FRIDAY MORNING...

The Flood Watch continues for

* Portions of northern Delaware...New Jersey...and Pennsylvania...
  including the following areas...in northern Delaware...New Castle. 
  In New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, 
  Sussex, and Warren. In Pennsylvania...Berks, Carbon, Delaware, 
  Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, 
  Northampton, Philadelphia, Upper Bucks, Western Chester, and 
  Western Montgomery.

* Through Friday morning

* Heavy rain will move into the region tonight, with between 1 and 3 
  inches of rain over the region and as much as 3 to 4 inches of 
  rain over the southern Poconos.

* Excessive rainfall and snowmelt will result in rises on rivers and 
  streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

MPS
017 
WGUS61 KPHI 250743
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
243 AM EST Fri Dec 25 2020

.Earlier heavy rain and snow melt has lead to flooding over portions 
of the region. Flows in Rivers may increase quickly and reach 
critical levels.

DEZ001-NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-
251700-
/O.CON.KPHI.FA.A.0004.000000T0000Z-201225T1700Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-
Carbon-Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western
Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper
Bucks-Lower Bucks-
Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, 
Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, 
Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West 
Chester, Morrisville, Wilmington, New Brunswick, Trenton, Newton, 
Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and 
Somerville
243 AM EST Fri Dec 25 2020

...FLOOD WATCH REMAINS IN EFFECT UNTIL NOON EST TODAY...

The Flood Watch continues for

* Portions of northern Delaware...New Jersey...and Pennsylvania...
  including the following areas...in northern Delaware...New Castle. 
  In New Jersey...Hunterdon, Mercer, Middlesex, Morris, Somerset, 
  Sussex, and Warren. In Pennsylvania...Berks, Carbon, Delaware, 
  Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks, Monroe, 
  Northampton, Philadelphia, Upper Bucks, Western Chester, and 
  Western Montgomery.

* Until Noon EST today

* Widespread 1 to 3 inches fell earlier tonight, and some lingering 
  light rain will continue through this morning. Flooding is already 
  ongoing in several locations, therefore, the flood watch continues 
  across the region.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Watch means there is a potential for flooding based on 
current forecasts. You should monitor later forecasts and be alert 
for possible flood warnings. Those living in areas prone to flooding 
should be prepared to take action should flooding develop.

&&

$$

SFJ
683 
WGUS61 KPHI 251436
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
936 AM EST Fri Dec 25 2020

DEZ001-NJZ001-007>010-012-015-PAZ054-055-060>062-070-071-101>106-
251545-
/O.CAN.KPHI.FA.A.0004.000000T0000Z-201225T1700Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle-Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-
Carbon-Monroe-Berks-Lehigh-Northampton-Delaware-Philadelphia-Western
Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper
Bucks-Lower Bucks-
Including the cities of Jim Thorpe, Flemington, Media, Philadelphia, 
Doylestown, Chalfont, Morristown, Honey Brook, Lansdale, Norristown, 
Reading, Pottstown, Allentown, Oxford, Kennett Square, Easton, West 
Chester, Morrisville, Wilmington, New Brunswick, Trenton, Newton, 
Washington, Collegeville, Bethlehem, Stroudsburg, Perkasie, and 
Somerville
936 AM EST Fri Dec 25 2020

...FLOOD WATCH IS CANCELLED...

The Flood Watch for portions of northern Delaware...New Jersey...and 
Pennsylvania...including the following areas...in northern 
Delaware...New Castle. In New Jersey...Hunterdon, Mercer, Middlesex, 
Morris, Somerset, Sussex, and Warren. In Pennsylvania...Berks, 
Carbon, Delaware, Eastern Chester, Eastern Montgomery, Lehigh, Lower 
Bucks, Monroe, Northampton, Philadelphia, Upper Bucks, Western 
Chester, and Western Montgomery has been cancelled.

The Flood Watch is cancelled. There are existing Flood Warnings in 
place, so please continue to heed remaining road closures.

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 22, 3:19 PM ESTGale WatchPHI24 hr

Nearby

Flood Watches in Pennsylvania, 2020Flood Watches in New Jersey, 2020Flood Watches in Delaware, 2020Every flood watch 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.