Alert archive / Pennsylvania / Flash Flood Warnings in 2018

Flash Flood Warning 85, NWS Philadelphia/Mount Holly

August 31, 2018Berks County, Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 31, 2018, 3:59 PM EDT for Berks County, Chester County, Pennsylvania. It was in force for 4 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
Aug 31, 2018, 3:59 PM EDT (19:59 UTC)
Expired
Aug 31, 2018, 8:00 PM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Berks County, PA, Chester County, PA

The radar

The Philadelphia radar (KDIX), 127 km from the middle of the area, began a volume at 19:59 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
Aug 31, 4:50 PM EDTFLASH FLOOD1 Ssw Wyomissing, PAAPPROXIMATELY 12 APARTMENT UNITS IN CAMBRIDGE COMMONS WERE DAMAGED DUE TO SIGNIFICANT FLOODING ALONG A TRIBUTARY OF THE WYOMISSING CREEK. RESIDENTS IN THE APARTMENT COMPLEX WERE EVACUATED BEFOREHAND.
Aug 31, 4:50 PM EDTFLASH FLOOD1 Ssw Wyomissing, PARESIDENTS IN AN APARTMENT BUILDING IN CAMBRIDGE COMMONS HAD TO BE EVACUATED DUE FLOODWATERS FROM A NEARBY CREEK.
Aug 31, 5:00 PM EDTFLASH FLOODSinking Spring, PAAT LEAST 10 WATER RESCUES REPORTED BETWEEN 4 AND 5 PM IN THE TOWNS OF SPRING TWP, SINKING SPRING AND WYOMISSING.
Aug 31, 5:09 PM EDTFLASH FLOOD1 Ese Sinking Spring, PAPHOTO SHOWS TWO CARS STUCK IN A FLOODED INTERSECTION AT PA 724 (SHILLINGTON ROAD) AND SPOHN ROAD.
Aug 31, 6:27 PM EDTFLASH FLOODWernersville, PAWIDESPREAD ROADWAY AND STREAM FLOODING THROUGHOUT THE AREA.
Aug 31, 6:27 PM EDTHEAVY RAIN 5Wernersville, PA
Aug 31, 7:03 PM EDTFLOOD2 Nne Mount Vernon, PAFLOODING ON SCROGGY AND CREAM ROADS ALONG THE OCTORARO CREEK. ALL LANES COVERED.

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 12:00Z, 8.0 hours before the alert went out and 173 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 2018-08-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 425 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 2018-08-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 20 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
425 J/kg
Mixed-layer CIN
-35 J/kg
Mixed-layer LCL
930 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
20 m²/s²
0-3 km storm-relative helicity
68 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

763 
WGUS51 KPHI 311959
FFWPHI
PAC011-029-010000-
/O.NEW.KPHI.FF.W.0085.180831T1959Z-180901T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
359 PM EDT FRI AUG 31 2018

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  South central Berks County in eastern Pennsylvania...
  Chester County in southeastern Pennsylvania...

* Until 800 PM EDT.

* At 357 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to two to three inches of 
  rain have already fallen with additional rainfall occuring. Flash 
  flooding is expected to begin shortly in the areas of heaviest 
  rain.

* Some locations that could experience flooding include...
  Reading, Coatesville, Wyomissing, Downingtown, Kennett Square,
  Birdsboro, Oxford, Sinking Spring, Laureldale, Parkesburg, West
  Grove, Wernersville, Leesport, Honey Brook, Elverson, New Morgan,
  Homeville, Glen Roy, Spring Ridge and Cochranville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.

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 4051 7593 3988 7558 3986 7560 3984 7558
      3982 7568 3972 7577 3972 7614 3976 7606
      3983 7604 3983 7602 3987 7599 3995 7600
      4004 7593 4011 7594 4014 7588 4034 7618

$$

Robertson
2 follow-up statements
704 
WGUS71 KPHI 312218
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
618 PM EDT FRI AUG 31 2018

PAC011-029-010000-
/O.CON.KPHI.FF.W.0085.000000T0000Z-180901T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Chester PA-
618 PM EDT FRI AUG 31 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 800 PM EDT FOR
SOUTH CENTRAL BERKS AND CHESTER COUNTIES...

At 615 PM EDT, the public reported flooding across the warned area, 
in particular near Sinking Spring with flooded roadways due to 3 to 
5 inches of rainfall from earlier storms. Several creeks and streams 
continue to rise, in particular the West Branch Brandywine Creek 
near Honey Brook which may exceed flood stage. Rainfall continues 
across the area and is expected to continue to lead to Flash 
flooding.

Some locations that could experience flooding include...
Reading, Coatesville, Wyomissing, Downingtown, Kennett Square,
Birdsboro, Oxford, Sinking Spring, Laureldale, Parkesburg, West
Grove, Wernersville, Leesport, Honey Brook, Elverson, New Morgan,
Homeville, Glen Roy, Spring Ridge and Cochranville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.

&&

LAT...LON 4051 7593 3988 7558 3986 7560 3984 7558
      3982 7568 3972 7577 3972 7614 3976 7606
      3983 7604 3983 7602 3987 7599 3995 7600
      4004 7593 4011 7594 4014 7588 4034 7618

$$

Robertson
048 
WGUS71 KPHI 312352
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
752 PM EDT FRI AUG 31 2018

PAC011-029-010000-
/O.EXP.KPHI.FF.W.0085.000000T0000Z-180901T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Chester PA-
752 PM EDT FRI AUG 31 2018

...THE FLASH FLOOD WARNING FOR SOUTH CENTRAL BERKS AND CHESTER
COUNTIES WILL EXPIRE AT 800 PM EDT...

The heavy rain has ended. Flash Flooding is no longer expected to 
pose a threat, however, many local creeks and stream continue to run 
high and there continues to be some roadway flooding. An Areal Flood 
Warning will be issued for any residual flooding. There will 
continue to be light to moderate rain through this evening as well 
which many exacerbate any flooding. Please continue to heed any 
remaining road closures.

LAT...LON 4051 7593 3988 7558 3986 7560 3984 7558
      3982 7568 3972 7577 3972 7614 3976 7606
      3983 7604 3983 7602 3987 7599 3995 7600
      4004 7593 4011 7594 4014 7588 4034 7618

$$

Robertson

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 31, 6:52 AM EDTAreal Flood AdvisoryPHIPhiladelphia4 hr
Aug 31, 7:55 AM EDTAreal Flood AdvisoryPHIDelaware3 hr
Aug 31, 10:09 AM EDTFlash Flood WarningPHIBerks7 hr
Aug 31, 10:14 AM EDTAreal Flood AdvisoryPHIChester3 hr
Aug 31, 1:22 PM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Northampton4 hr
Aug 31, 1:54 PM EDTAreal Flood AdvisoryPHIBerks, Chester, Lehigh, Montgomery4 hr
Aug 31, 5:13 PM EDTAreal Flood WarningPHIBerks7 hr

Nearby

Flash 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.