Alert archive / Pennsylvania / Flash Flood Warnings in 2019

Flash Flood Warning 39, NWS Philadelphia/Mount Holly

July 4, 20194 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 4, 2019, 5:49 PM EDT for 4 counties in Pennsylvania. It was in force for 115 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 4, 2019, 5:49 PM EDT (21:49 UTC)
Expired
Jul 4, 2019, 7:44 PM EDT
In force
115 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 77 km from the middle of the area, began a volume at 21:51 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.8 hours before the alert went out and 215 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, Washington/Dulle, VA at 12:00Z on 2019-07-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 494 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, Washington/Dulle, VA at 12:00Z on 2019-07-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 6 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
494 J/kg
Mixed-layer CIN
-76 J/kg
Mixed-layer LCL
1204 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
6 m²/s²
0-3 km storm-relative helicity
59 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

748 
WGUS51 KPHI 042149
FFWPHI
PAC029-045-091-101-050145-
/O.NEW.KPHI.FF.W.0039.190704T2149Z-190705T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
549 PM EDT Thu Jul 4 2019

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  South central Montgomery County in southeastern Pennsylvania...
  East central Chester County in southeastern Pennsylvania...
  Southwestern Philadelphia County in southeastern Pennsylvania...
  Northeastern Delaware County in southeastern Pennsylvania...

* Until 945 PM EDT.

* At 549 PM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to two inches of rain have
  already fallen. Flash flooding is expected to begin shortly in the
  areas of heaviest rain.

* Some locations that could experience flooding include...
  Philadelphia, Yeadon, Narberth, East Lansdowne, Morris Park,
  Germantown, Bryn Mawr, Trout Lake, Radnor Township, Broomall,
  Newtown Square, Roxborough, Drexel Hill, Paoli, King Of Prussia,
  Darby, Lansdowne, Clifton Heights, West Conshohocken and
  Millbourne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Move to higher ground now. Act quickly to protect your life.

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.

Please report flooding to your local law enforcement agency when you
can do so safely.

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 4005 7518 3992 7520 3996 7552 4009 7545

$$

MPS
1 follow-up statement
650 
WGUS71 KPHI 042344
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
744 PM EDT Thu Jul 4 2019

PAC029-045-091-101-042354-
/O.CAN.KPHI.FF.W.0039.000000T0000Z-190705T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
744 PM EDT Thu Jul 4 2019

...THE FLASH FLOOD WARNING FOR SOUTH CENTRAL MONTGOMERY...EAST
CENTRAL CHESTER...SOUTHWESTERN PHILADELPHIA AND NORTHEASTERN DELAWARE
COUNTIES IS CANCELLED...

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

LAT...LON 4005 7518 3992 7520 3996 7552 4009 7545

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 4, 3:26 PM EDTSpecial Weather StatementPHIChester49 min
Jul 4, 4:28 PM EDTFlash Flood WarningPHIChester2 hr
Jul 4, 4:53 PM EDTSpecial Weather StatementPHIDelaware37 min
Jul 4, 5:18 PM EDTAreal Flood AdvisoryPHIChester, Delaware, Montgomery, Philadelphia32 min
Jul 4, 5:42 PM EDTAreal Flood AdvisoryPHIBerks, Chester, Montgomery2 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2019Every flash flood warning in 2019

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.