Alert archive / New Jersey / Flash Flood Warnings in 2018

Flash Flood Warning 102, NWS Philadelphia/Mount Holly

September 25, 2018Mercer County, Middlesex County, Somerset County, New Jersey; Bucks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 25, 2018, 5:14 PM EDT for Mercer County, Middlesex County, Somerset County, New Jersey; Bucks County, Pennsylvania. It was in force for 4 hr. 3 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 25, 2018, 5:14 PM EDT (21:14 UTC)
Expired
Sep 25, 2018, 9:15 PM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

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

The radar

The Philadelphia radar (KDIX), 46 km from the middle of the area, began a volume at 21:18 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.

What was reported inside it

TimeReportWhereRemark
Sep 25, 6:15 PM EDTFLASH FLOOD1 Wsw White Horse, NJFLOODING AT UNDERPASSES AT THE INTERSECTION OF I-195 AND I-295.
Sep 25, 6:15 PM EDTFLASH FLOODTrenton, NJMULTIPLE INTERSECTIONS AND ROADWAYS ARE BEGINNING TO FLOOD. 2.5 INCHES OF RAIN RECEIVED SO FAR TODAY.
Sep 25, 6:47 PM EDTFLOODMorrisville, PASEVERAL ROADWAYS FLOODED IN THE AREA.

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, 9.2 hours before the alert went out and 175 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 2018-09-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCLEL10008507005003002001001 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 2018-09-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 413 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
457 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
413 m²/s²
0-3 km storm-relative helicity
577 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

202 
WGUS51 KPHI 252114
FFWPHI
NJC021-023-035-PAC017-260115-
/O.NEW.KPHI.FF.W.0102.180925T2114Z-180926T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
514 PM EDT TUE SEP 25 2018

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Mercer County in central New Jersey...
  South central Somerset County in northern New Jersey...
  Southwestern Middlesex County in northern New Jersey...
  Southeastern Bucks County in southeastern Pennsylvania...

* Until 915 PM EDT.

* At 513 PM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Flash flooding is expected to
  begin shortly in the areas of heaviest rain.

* Some locations that could experience flooding include...
  Trenton, Ewing, Princeton, Bristol, Hightstown, Cranbury,
  Pennington, Yardley, Hopewell, Tullytown, Rocky Hill, Washington
  Crossing, Skillman, Princeton Meadows, Windsor, Kingston,
  Plainsboro Center, Clearbrook Park, Edinburg and White Horse.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

LAT...LON 4009 7489 4024 7484 4032 7493 4046 7463
      4030 7445

$$

Fitzsimmons
2 follow-up statements
154 
WGUS71 KPHI 252346
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
746 PM EDT TUE SEP 25 2018

NJC021-023-035-PAC017-260115-
/O.CON.KPHI.FF.W.0102.000000T0000Z-180926T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Somerset NJ-Middlesex NJ-Bucks PA-
746 PM EDT TUE SEP 25 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 PM EDT FOR
MERCER...SOUTH CENTRAL SOMERSET...SOUTHWESTERN MIDDLESEX AND
SOUTHEASTERN BUCKS COUNTIES...

At 742 PM EDT, the heavy rain that prompted the Flash Flood Warning 
has moved out of the area. However there have been reports of 
multiple flooded roadways across Mercer County and rises continue on 
area creeks, streams, and rivers as the water makes its way through 
the river system. Therefore, the Flash Flood Warning remains in 
effect. 

Some locations that could experience flooding include...
Trenton, Ewing, Princeton, Bristol, Hightstown, Cranbury, Pennington,
Yardley, Hopewell, Tullytown, Rocky Hill, Washington Crossing,
Skillman, Princeton Meadows, Windsor, Kingston, Plainsboro Center,
Clearbrook Park, Edinburg and White Horse.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

LAT...LON 4009 7489 4024 7484 4032 7493 4046 7463
      4030 7445

$$

Fitzsimmons
747 
WGUS71 KPHI 260113
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
913 PM EDT TUE SEP 25 2018

NJC021-023-035-PAC017-260122-
/O.EXP.KPHI.FF.W.0102.000000T0000Z-180926T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Somerset NJ-Middlesex NJ-Bucks PA-
913 PM EDT TUE SEP 25 2018

...THE FLASH FLOOD WARNING FOR MERCER...SOUTH CENTRAL SOMERSET...
SOUTHWESTERN MIDDLESEX AND SOUTHEASTERN BUCKS COUNTIES WILL EXPIRE AT
915 PM EDT...

The heavy rain has ended. Flash flooding is no longer expected to 
pose a threat. Please continue to heed any remaining road closures.

LAT...LON 4009 7489 4024 7484 4032 7493 4046 7463
      4030 7445

$$

Fitzsimmons

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 25, 12:07 PM EDTSpecial Weather StatementPHIHunterdon, Morris, Somerset, Sussex, Warren23 min
Sep 25, 12:33 PM EDTRip Current StatementPHIAtlantic, Cape May, Monmouth, Ocean8 hr
Sep 25, 12:47 PM EDTSpecial Weather StatementPHIMorris, Somerset, Sussex43 min
Sep 25, 2:30 PM EDTAreal Flood AdvisoryPHIHunterdon, Morris, Somerset3 hr
Sep 25, 4:03 PM EDTAreal Flood AdvisoryPHIBurlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 1 more3 hr
Sep 25, 4:19 PM EDTFlash Flood WarningPHICamden4 hr
Sep 25, 5:35 PM EDTFlash Flood WarningPHIBurlington, Camden, Gloucester, Mercer4 hr
Sep 25, 6:03 PM EDTFlash Flood WarningPHIMercer, Middlesex, Monmouth3 hr
Sep 25, 6:39 PM EDTAreal Flood AdvisoryPHIAtlantic, Burlington, Camden, Gloucester, Ocean3 hr
Sep 25, 6:47 PM EDTTornado WarningPHIBurlington32 min
Sep 25, 7:21 PM EDTSevere Thunderstorm WarningPHIMonmouth17 min
Sep 25, 2:59 PM EDTAreal Flood AdvisoryPHIBucks, Chester, Delaware, Lehigh, Montgomery4 hr

Nearby

Flash Flood Warnings in New Jersey, 2018Flash Flood Warnings in Pennsylvania, 2018Every flash flood warning in 2018

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.