Alert archive / Pennsylvania / Flash Flood Warnings in 2019

Flash Flood Warning 28, NWS Philadelphia/Mount Holly

June 20, 2019Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 20, 2019, 12:45 AM EDT for Montgomery County, Philadelphia County, Pennsylvania. It was in force for 6 hr. 7 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
Jun 20, 2019, 12:45 AM EDT (04:45 UTC)
Expired
Jun 20, 2019, 6:17 AM EDT
In force
6 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 85 km from the middle of the area, began a volume at 04:45 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
Jun 20, 1:39 AM EDTFLASH FLOOD1 E South Philadelphia, PASEVERAL ROADS CLOSED IN THE AREA OF 38TH STREET, 34TH STREET, 26TH STREET, AND UNIVERSITY AVENUE FROM FLASH FLOODING.
Jun 20, 4:45 AM EDTFLASH FLOOD2 Wsw West Norriton, PASOUTH TROOPER ROAD FLOODED BETWEEN VAN BUREN AVENUE AND MONROE BOULEVARD WITH LANE CLOSURES.
Jun 20, 5:00 AM EDTFLOODLower Providence, PASOUTH PARK AVE CLOSED NEAR WOODLAND AVE.
Jun 20, 5:00 AM EDTFLASH FLOOD1 N Oreland, PAWATER RESCUE ON PENNSYLVANIA AVE.
Jun 20, 5:00 AM EDTFLASH FLOOD1 N Oreland, PAWATER RESCUE ON VIRGINIA DR.
Jun 20, 5:30 AM EDTFLASH FLOOD1 Ssw West Norriton, PAFLOODING ON BEIDLER ROAD AND HENDERSON ROAD, FORCING ROAD CLOSURES. TIME ESTIMATED FROM RADAR AND NEARBY REPORTS.
Jun 20, 5:43 AM EDTFLASH FLOOD2 Wsw West Norriton, PASTATE HIGHWAY 363 CLOSED FROM FLASH FLOODING. WATER RESCUES REPORTED.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 4.8 hours before the alert went out and 216 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 00:00Z on 2019-06-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1341 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 00:00Z on 2019-06-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 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
1341 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
1152 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
76 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.2

Open this sounding in Storm Lab

The text

As transmitted.

667 
WGUS51 KPHI 200445
FFWPHI
PAC091-101-201045-
/O.NEW.KPHI.FF.W.0028.190620T0445Z-190620T1045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1245 AM EDT Thu Jun 20 2019

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Montgomery County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...

* Until 645 AM EDT Thursday.

* At 1240 AM EDT, Doppler radar indicated showers and thunderstorms 
  producing heavy rain across the warned area. Conditions are 
  already saturated. Flash flooding is expected to begin shortly in 
  the areas of heaviest rain.

* Some locations that could experience flooding include...
  Philadelphia, Norristown, Pottstown, Lansdale, West Norriton, East 
  Norriton, Conshohocken, Hatboro, Souderton, Ambler, Collegeville, 
  Royersford, Jenkintown, Narberth, Trappe, Hatfield and East 
  Greenville.

Additional rainfall amounts in excess of an inch are possible in the 
warned area.

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 poor drainage areas and low lying spots.

&&

LAT...LON 4045 7553 4011 7496 4005 7498 3996 7513
      3988 7515 3988 7526 3996 7525 4006 7535
      4006 7539 4009 7542 4009 7545 4013 7546
      4014 7551 4016 7550 4015 7553 4024 7560
      4022 7561 4024 7570

$$

Iovino
1 follow-up statement
547 
WGUS71 KPHI 201017
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
617 AM EDT Thu Jun 20 2019

PAC091-101-201026-
/O.CAN.KPHI.FF.W.0028.000000T0000Z-190620T1045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Philadelphia PA-
617 AM EDT Thu Jun 20 2019

...THE FLASH FLOOD WARNING FOR MONTGOMERY AND PHILADELPHIA COUNTIES
IS CANCELLED...

The Flash Flood Warning has been converted to an areal Flood Warning 
and it is in effect until 12:15 PM this afternoon. Please continue 
to heed any road closures.

LAT...LON 4045 7553 4011 7496 4005 7498 3996 7513
      3988 7515 3988 7526 3996 7525 4006 7535
      4006 7539 4009 7542 4009 7545 4013 7546
      4014 7551 4016 7550 4015 7553 4024 7560
      4022 7561 4024 7570

$$

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 19, 9:09 PM EDTAreal Flood WarningPHIPhiladelphia3 hr
Jun 19, 9:50 PM EDTSpecial Weather StatementPHILebanon55 min
Jun 19, 10:47 PM EDTAreal Flood AdvisoryPHIBerks50 min
Jun 19, 11:11 PM EDTFlash Flood WarningPHIChester, Delaware6 hr
Jun 19, 11:34 PM EDTFlash Flood WarningPHIBerks6 hr
Jun 20, 12:39 AM EDTAreal Flood AdvisoryPHIMontgomery7 min
Jun 20, 3:40 AM EDTRiver Flood WarningPHIDelaware111 min
Jun 20, 3:59 AM EDTRiver Flood WarningPHIChester7 hr
Jun 20, 5:10 AM EDTAreal Flood WarningPHIChester, Delaware12 hr
Jun 20, 5:19 AM EDTRiver Flood WarningPHIChester, Delaware13 hr
Jun 20, 5:24 AM EDTAreal Flood WarningPHIBerks6 hr
Jun 20, 6:14 AM EDTAreal Flood WarningPHIMontgomery, Philadelphia10 hr
Jun 20, 6:31 AM EDTRiver Flood WarningPHIDelaware3 hr
Jun 20, 1:24 PM EDTSpecial Weather StatementPHIBerks, Chester, Montgomery51 min
Jun 20, 1:28 PM EDTAreal Flood AdvisoryPHIBerks4 hr
Jun 20, 2:13 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Chester, Delaware, Lehigh, Montgomery4 hr
Jun 20, 2:26 PM EDTSpecial Weather StatementPHIBucks, Chester, Delaware, Montgomery, Philadelphia94 min
Jun 20, 2:33 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia57 min
Jun 20, 2:48 PM EDTFlash Flood WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia4 hr
Jun 20, 3:20 PM EDTFlash Flood WarningPHIBucks4 hr
Jun 20, 4:58 PM EDTRiver Flood WarningPHIChester4 hr
Jun 20, 6:33 PM EDTAreal Flood WarningPHIMontgomery3 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.