Alert archive / Pennsylvania / Flash Flood Warnings in 2015

Flash Flood Warning 46, NWS Philadelphia/Mount Holly

August 19, 2015Bucks County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 19, 2015, 4:35 PM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 19, 2015, 4:35 PM EDT (20:35 UTC)
Expired
Aug 19, 2015, 7:30 PM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Bucks County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 69 km from the middle of the area, began a volume at 20:36 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, 8.6 hours before the alert went out and 205 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 2015-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 605 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, Brookhaven, NY at 12:00Z on 2015-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -23 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
605 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
642 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
-23 m²/s²
0-3 km storm-relative helicity
-1 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

811 
WGUS51 KPHI 192035
FFWPHI
PAC017-091-101-192330-
/O.NEW.KPHI.FF.W.0046.150819T2035Z-150819T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
435 PM EDT WED AUG 19 2015

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ  HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL BUCKS COUNTY IN SOUTHEASTERN PENNSYLVANIA...
  SOUTHEASTERN MONTGOMERY COUNTY IN SOUTHEASTERN PENNSYLVANIA...
  NORTHWESTERN PHILADELPHIA COUNTY IN SOUTHEASTERN PENNSYLVANIA...

* UNTIL 730 PM EDT
    
* AT 433 PM EDT...DOPPLER RADAR INDICATED A THUNDERSTORM PRODUCING 
  HEAVY RAIN ACROSS THE WARNED AREA. BETWEEN ONE AND TWO INCHES OF 
  RAIN HAVE ALREADY FALLEN. FLASH FLOODING IS EXPECTED TO BEGIN 
  SHORTLY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE... NORTHEAST 
  PHILADELPHIA...DOYLESTOWN...HATBORO...AMBLER...JENKINTOWN...  
  CHALFONT...ABINGTON...BRYN ATHYN...IVYLAND...GERMANTOWN... 
  GARDENVILLE...WILLOW GROVE...CHESTNUT HILL...RICHBORO...HORSHAM... 
  NEW BRITAIN...ORELAND...BRITTANY FARMS-HIGHLANDS...WYNDMOOR AND 
  GLENSIDE.

ADDITIONAL RAINFALL AMOUNTS OF UP TO TWO INCHES ARE POSSIBLE IN THE 
WARNED AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOVE TO HIGHER GROUND NOW. ACT QUICKLY TO PROTECT YOUR LIFE.

PLEASE REPORT FLOODING TO YOUR LOCAL LAW ENFORCEMENT AGENCY WHEN YOU
CAN DO SO SAFELY.

&&

LAT...LON 4001 7515 4006 7524 4029 7523 4039 7518
      4042 7509 4034 7503 4025 7499

$$

JRK
2 follow-up statements
105 
WGUS71 KPHI 192135
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
535 PM EDT WED AUG 19 2015

PAC017-091-101-192330-
/O.CON.KPHI.FF.W.0046.000000T0000Z-150819T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BUCKS PA-MONTGOMERY PA-PHILADELPHIA PA-
535 PM EDT WED AUG 19 2015

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM EDT FOR
CENTRAL BUCKS...SOUTHEASTERN MONTGOMERY AND NORTH CENTRAL
PHILADELPHIA COUNTIES...

AT 529 PM EDT...DOPPLER RADAR INDICATED UP TO TWO INCHES OF RAIN HAS 
FALLEN ACROSS THE WARNED AREA. THE HEAVY RAIN HAS ENDED BUT 
EXCESSIVE RUNOFF FROM EARLIER RAINFALL COULD STILL LEAD TO FLASH 
FLOODING...ESPECIALLY IN URBAN AND POOR DRAINAGE AREAS.

SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE... 
PHILADELPHIA...DOYLESTOWN...HATBORO...JENKINTOWN...ABINGTON...BRYN 
ATHYN...IVYLAND...WILLOW GROVE...GARDENVILLE...HORSHAM...NEW 
BRITAIN...WYNDMOOR...ORELAND...GLENSIDE...WYNCOTE...MAPLE 
GLEN...FORT WASHINGTON...WARMINSTER HEIGHTS AND FLOURTOWN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TURN AROUND...DON'T DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

PLEASE REPORT FLOODING TO YOUR LOCAL LAW ENFORCEMENT AGENCY WHEN YOU
CAN DO SO SAFELY.

&&

LAT...LON 4004 7513 4004 7518 4005 7520 4016 7521
      4024 7516 4037 7519 4038 7518 4042 7509
      4031 7502 4018 7505 4014 7507

$$

JRK
503 
WGUS71 KPHI 192218
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
618 PM EDT WED AUG 19 2015

PAC017-091-101-192227-
/O.CAN.KPHI.FF.W.0046.000000T0000Z-150819T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BUCKS PA-MONTGOMERY PA-PHILADELPHIA PA-
618 PM EDT WED AUG 19 2015

...THE FLASH FLOOD WARNING FOR CENTRAL BUCKS...SOUTHEASTERN
MONTGOMERY AND NORTH CENTRAL PHILADELPHIA COUNTIES IS CANCELLED...

A BRIEF DOWNPOUR IS STILL POSSIBLE WITH A SHOWER OVER THE AREA BUT 
THE HEAVY RAINFALL HAS ENDED...AND FLOODING IS NO LONGER EXPECTED TO 
POSE A THREAT.

LAT...LON 4004 7513 4004 7518 4005 7520 4016 7521
      4024 7516 4037 7519 4038 7518 4042 7509
      4031 7502 4018 7505 4014 7507

$$

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 19, 12:46 PM EDTAreal Flood AdvisoryPHIChester119 min
Aug 19, 4:19 PM EDTAreal Flood AdvisoryPHIBucks, Montgomery, Philadelphia116 min

Nearby

Flash Flood Warnings in Pennsylvania, 2015Every flash flood warning in 2015

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.