Alert archive / New Jersey / Flash Flood Warnings in 2020

Flash Flood Warning 59, NWS Philadelphia/Mount Holly

August 13, 20204 counties in New Jersey; Bucks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 13, 2020, 8:37 AM EDT for 4 counties in New Jersey; Bucks County, Pennsylvania. It was in force for 3 hr. 10 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: Aug 13, 2020, 8:37 AM EDT (12:37 UTC)
Expired: Aug 13, 2020, 11:07 AM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Somerset County, NJ, Bucks County, PA

The radar

The Philadelphia radar (KDIX), 60 km from the middle of the area, began a volume at 12:39 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

Time	Report	Where	Remark
Aug 13, 8:55 AM EDT	FLOOD	1 Se Doylestown, PA	FLOODING AT THE DOYLESTOWN COUNTRY CLUB. TIME BASED ON SOCIAL MEDIA POSTS.
Aug 13, 9:00 AM EDT	FLASH FLOOD	2 Ese Furlong, PA	EM REPORTS SEVERAL ROADS CLOSED IN BUCKINGHAM TOWNSHIP, INCLUDING SMITH ROAD, NEW HOPE ROAD, FOREST GROVE ROAD, ROUTE 413, AND LOWER MOUNTAIN ROAD.
Aug 13, 9:12 AM EDT	FLOOD	1 Ssw Heathcote, NJ	FLOODING ON U.S. HIGHWAY 1 SOUTHBOUND SOUTH OF RAYMOND ROAD. LANE RESTRICTIONS IN PLACE. TIME BASED ON DISPATCH REPORT.
Aug 13, 9:30 AM EDT	FLASH FLOOD	1 Wsw Buckingham Twp, PA	CORRECTS PREVIOUS FLASH FLOOD REPORT FROM 1 WNW FRICKS. FLOODING ON MILL ROAD IN DOYLESTOWN. TIME BASED ON DISPATCH REPORT.
Aug 13, 10:23 AM EDT	FLOOD	2 Se South Bound Brook, NJ	FLOODING ON INTERSTATE 287 SOUTHBOUND SOUTH OF EXIT 9. LANE RESTRICTIONS REQUIRED. TIME BASED ON DISPATCH REPORT.
Aug 13, 11:00 AM EDT	HEAVY RAIN 1.99	1 W Monmmouth Junction, NJ	PERSONAL WEATHER STATION KNJSOUTH112.
Aug 13, 11:00 AM EDT	HEAVY RAIN 2.32	3 W Kendall Park, NJ	PERSONAL WEATHER STATION KNJFRANK42.
Aug 13, 11:00 AM EDT	HEAVY RAIN 2.32	3 W Kendall Park, NJ
Aug 13, 11:00 AM EDT	HEAVY RAIN 2.43	1 Ssw Princeton, NJ
Aug 13, 11:00 AM EDT	HEAVY RAIN 3.15	2 Ese Furlong, PA

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 12:00Z, 0.6 hours before the alert went out and 163 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1326 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 599 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: 26 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

346 
WGUS51 KPHI 131237
FFWPHI
NJC019-021-023-035-PAC017-131630-
/O.NEW.KPHI.FF.W.0059.200813T1237Z-200813T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
837 AM EDT Thu Aug 13 2020

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Southeastern Hunterdon County in northwestern New Jersey...
  Northern Mercer County in central New Jersey...
  Southern Somerset County in northern New Jersey...
  Central Middlesex County in northern New Jersey...
  Central Bucks County in southeastern Pennsylvania...

* Until 1230 PM EDT.

* At 837 AM EDT, Doppler radar and automated gauges indicated
  thunderstorms producing heavy rain across the warned area. Up to
  two inches of rain have already fallen. Flash flooding is ongoing
  or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

  IMPACT...Flooding of small creeks and streams, urban areas, 
           highways, streets and underpasses as well as other 
           drainage and low lying areas.

* Some locations that could experience flooding include...
  New Brunswick, Somerville, Somerset, Edison, East Brunswick, South
  Brunswick, North Brunswick, Ewing, Middlesex, Princeton, Bound
  Brook, Manville, Doylestown, Jamesburg, Cranbury, Pennington, New
  Hope, Hopewell, Rocky Hill and Millstone.

Additional rainfall amounts of 1 to 2 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 4056 7462 4058 7431 4033 7441 4022 7514
      4031 7513 4045 7477

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

JEO

2 follow-up statements

896 
WGUS71 KPHI 131317
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
917 AM EDT Thu Aug 13 2020

NJC019-021-023-035-PAC017-131630-
/O.CON.KPHI.FF.W.0059.000000T0000Z-200813T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Somerset NJ-Middlesex NJ-Bucks PA-
917 AM EDT Thu Aug 13 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1230 PM EDT FOR
SOUTHEASTERN HUNTERDON...NORTHERN MERCER...SOUTHERN SOMERSET...
CENTRAL MIDDLESEX AND CENTRAL BUCKS COUNTIES...

At 913 AM EDT, Doppler radar and automated gauges indicated 
thunderstorms producing heavy rain across the warned area. Up to two 
and a half inches of rain have already fallen. Flash flooding is 
ongoing or expected to begin shortly. While areas of flooding remain 
possible throughout the warned area, the greatest threat of flooding 
is near the northeastern portion of the warning in Middlesex and 
Somerset Counties, as well as the southwestern portion of the 
warning in Bucks County.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar and automated gauges.

IMPACT...Flooding of small creeks and streams, urban areas, 
         highways, streets and underpasses as well as other drainage 
         and low lying areas.

Some locations that could experience flooding include...
New Brunswick, Somerville, Somerset, Edison, East Brunswick, South
Brunswick, North Brunswick, Ewing, Middlesex, Princeton, Bound Brook,
Manville, Doylestown, Jamesburg, Cranbury, Pennington, New Hope,
Hopewell, Rocky Hill and Millstone.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 4056 7462 4058 7431 4033 7441 4022 7514
      4031 7513 4045 7477

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

JEO

136 
WGUS71 KPHI 131507
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1107 AM EDT Thu Aug 13 2020

NJC019-021-023-035-PAC017-131516-
/O.CAN.KPHI.FF.W.0059.000000T0000Z-200813T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Somerset NJ-Middlesex NJ-Bucks PA-
1107 AM EDT Thu Aug 13 2020

...THE FLASH FLOOD WARNING FOR SOUTHEASTERN HUNTERDON...NORTHERN
MERCER...SOUTHERN SOMERSET...CENTRAL MIDDLESEX AND CENTRAL BUCKS
COUNTIES IS CANCELLED...

The heavy rain has ended. Flood waters are receding. Flooding is no 
longer expected to pose a threat. Please continue to heed any 
remaining road closures.

LAT...LON 4056 7462 4058 7431 4033 7441 4022 7514
      4031 7513 4045 7477

$$

JEO

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 13, 3:02 AM EDT	Flash Flood Watch	PHI	Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 7 more	17 hr
Aug 13, 7:47 AM EDT	Areal Flood Advisory	PHI	Hunterdon, Mercer, Middlesex, Somerset	118 min
Aug 13, 9:36 AM EDT	Areal Flood Advisory	PHI	Hunterdon, Middlesex, Morris, Somerset	114 min
Aug 13, 10:01 AM EDT	Flash Flood Warning	PHI	Middlesex, Morris, Somerset	3 hr
Aug 13, 1:06 PM EDT	Special Weather Statement	PHI	Ocean	39 min
Aug 13, 1:30 PM EDT	Special Weather Statement	PHI	Cumberland	45 min
Aug 13, 1:56 PM EDT	Areal Flood Advisory	PHI	Atlantic, Cape May, Cumberland	2 hr
Aug 13, 1:58 PM EDT	Areal Flood Advisory	PHI	Atlantic, Burlington, Ocean	2 hr
Aug 13, 2:44 PM EDT	Areal Flood Advisory	PHI	Atlantic	2 hr
Aug 13, 3:54 PM EDT	Special Weather Statement	PHI	Cape May	36 min
Aug 13, 4:01 PM EDT	Areal Flood Advisory	PHI	Cape May	2 hr
Aug 13, 4:52 PM EDT	Flash Flood Warning	PHI	Cape May	113 min
Aug 13, 7:25 AM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery	2 hr
Aug 13, 9:07 AM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	3 hr
Aug 13, 3:30 PM EDT	Areal Flood Advisory	PHI	Philadelphia	3 hr
Aug 13, 3:56 PM EDT	Areal Flood Advisory	PHI	Delaware	2 hr
Aug 13, 4:45 PM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	84 min

Nearby

Flash Flood Warnings in New Jersey, 2020 Flash Flood Warnings in Pennsylvania, 2020 Every flash flood warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.