Alert archive / Pennsylvania / Flash Flood Warnings in 2021

Flash Flood Warning 66, NWS Philadelphia/Mount Holly

September 1, 2021Berks County, Lehigh County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 1, 2021, 1:29 PM EDT for Berks County, Lehigh 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
Sep 1, 2021, 1:29 PM EDT (17:29 UTC)
Expired
Sep 1, 2021, 7:23 PM EDT
In force
6 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Berks County, PA, Lehigh County, PA

The radar

The Philadelphia radar (KDIX), 149 km from the middle of the area, began a volume at 17:29 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 1, 3:20 PM EDTFLASH FLOOD1 Ssw Temple, PAMULTIPLE REPORTS FROM MPING: OF STREET/ROAD FLOODING ACROSS CENTRAL BERKS COUNTY.
Sep 1, 4:32 PM EDTFLASH FLOOD1 Ssw Bernville, PANORTH HEIDELBERG ROAD AND BERNVILLE ROAD CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.
Sep 1, 5:34 PM EDTFLASH FLOOD1 S Muhlenberg Twp, PAROUTE 12 CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.
Sep 1, 5:42 PM EDTFLASH FLOOD3 N Exeter Twp, PASPIES CHURCH ROAD AND MONOCACY CREEK ROAD CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.
Sep 1, 6:19 PM EDTFLASH FLOODStrausstown, PAFLOODING CLOSED OLD ROUTE 22 AT STATE HIGHWAY 183. TIME BASED ON DISPATCH REPORT.
Sep 1, 6:24 PM EDTFLASH FLOOD2 Sw South Heidelberg T, PAFLOODING CLOSED FRITZTOWN ROAD NEAR THE LANCASTER COUNTY BORDER. TIME BASED ON DISPATCH REPORT.
Sep 1, 6:45 PM EDTFLASH FLOOD3 Sw Earl Twp, PATHE GAUGE ON MANATAWNY CREEK AT SPANGVILLE (SPGP1) REACHED FLOOD STAGE AT 645 PM 9/1, CRESTING AT 8.54 FEET (MAJOR FLOODING) AT 1030 PM 9/1.

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, 5.5 hours before the alert went out and 206 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 2021-09-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 558 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 12:00Z on 2021-09-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 122 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
558 J/kg
Mixed-layer CIN
-21 J/kg
Mixed-layer LCL
575 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
122 m²/s²
0-3 km storm-relative helicity
223 m²/s²
Significant tornado parameter
0.4
Supercell composite
2.6

Open this sounding in Storm Lab

The text

As transmitted.

563 
WGUS51 KPHI 011729
FFWPHI
PAC011-077-012130-
/O.NEW.KPHI.FF.W.0066.210901T1729Z-210901T2130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
129 PM EDT Wed Sep 1 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Berks County in eastern Pennsylvania...
  Southwestern Lehigh County in eastern Pennsylvania...

* Until 530 PM EDT.

* At 129 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly. Several inches of rain are expected through the afternoon.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets, and underpasses as well as other
           drainage and low lying areas.

* Some locations that may experience flash flooding include...
  Reading, Wyomissing, Birdsboro, Kutztown, Hamburg, Fleetwood, 
  Sinking Spring, Laureldale, Womelsdorf, Wernersville, Topton, and 
  Robesonia.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 296 and 298.
	Interstate 78 in Pennsylvania between mile markers 10 and 45.
	Interstate 176 in Pennsylvania between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4068 7589 4051 7562 4024 7573 4015 7590
      4031 7615 4036 7621 4037 7623 4050 7644
      4054 7617 4058 7604 4057 7602 4064 7599

FLASH FLOOD...RADAR INDICATED

$$

NC
2 follow-up statements
972 
WGUS51 KPHI 012115
FFWPHI
PAC011-077-012330-
/O.EXT.KPHI.FF.W.0066.000000T0000Z-210901T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
515 PM EDT Wed Sep 1 2021

The National Weather Service in Mount Holly has extended the

* Flash Flood Warning for...
  Berks County in eastern Pennsylvania...
  Southwestern Lehigh County in eastern Pennsylvania...

* Until 730 PM EDT.

* At 515 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain in the Reading area. Between 2 and 4 inches of rain 
  have fallen, and an additional 1 to 2 inches of rainfall are 
  expected over the next few hours. Flash flooding is already 
  occurring.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets, and underpasses as well as other
           drainage and low lying areas.

* Some locations that may experience flash flooding include...
  Reading, Wyomissing, Birdsboro, Kutztown, Hamburg, Fleetwood, 
  Sinking Spring, Laureldale, Womelsdorf, Wernersville, Topton, and 
  Robesonia.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 296 and 298.
	Interstate 78 in Pennsylvania between mile markers 10 and 45.
	Interstate 176 in Pennsylvania between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4068 7589 4051 7562 4024 7573 4015 7590
      4031 7615 4036 7621 4037 7623 4050 7644
      4054 7617 4058 7604 4057 7602 4064 7599

FLASH FLOOD...RADAR INDICATED

$$

NC
054 
WGUS71 KPHI 012323
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
723 PM EDT Wed Sep 1 2021

PAC011-077-012333-
/O.CAN.KPHI.FF.W.0066.000000T0000Z-210901T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Lehigh PA-
723 PM EDT Wed Sep 1 2021

...FLASH FLOOD WARNING FOR BERKS AND SOUTHWESTERN LEHIGH COUNTIES 
HAS BEEN REPLACED WITH A FLOOD WARNING...

LAT...LON 4068 7589 4051 7562 4024 7573 4015 7590
      4031 7615 4036 7621 4037 7623 4050 7644
      4054 7617 4058 7604 4057 7602 4064 7599

$$

NC

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 1, 6:19 AM EDTAreal Flood AdvisoryPHIChester, Delaware116 min
Sep 1, 6:49 AM EDTFlash Flood WarningPHIChester, Delaware, Philadelphia86 min
Sep 1, 11:24 AM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Northampton3 hr
Sep 1, 12:07 PM EDTFlash Flood WarningPHICarbon, Monroe4 hr
Sep 1, 2:53 PM EDTFlash Flood WarningPHIBerks, Chester, Delaware, Montgomery9 hr
Sep 1, 3:55 PM EDTRiver Flood WarningPHIMontgomery36 hr
Sep 1, 3:55 PM EDTRiver Flood WarningPHIChester, Montgomery, Philadelphia43 hr
Sep 1, 3:55 PM EDTRiver Flood WarningPHIMontgomery, Philadelphia41 hr
Sep 1, 3:55 PM EDTRiver Flood WarningPHIPhiladelphia39 hr
Sep 1, 3:55 PM EDTRiver Flood WarningPHIBerks24 hr
Sep 1, 4:02 PM EDTRiver Flood WarningPHIMonroe24 hr
Sep 1, 4:04 PM EDTAreal Flood WarningPHICarbon, Monroe, Northampton24 hr
Sep 1, 4:10 PM EDTRiver Flood WarningPHIMonroe19 hr
Sep 1, 4:12 PM EDTFlash Flood WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton7 hr
Sep 1, 4:12 PM EDTRiver Flood WarningPHILehigh, Northampton25 hr
Sep 1, 4:12 PM EDTRiver Flood WarningPHILehigh, Northampton24 hr
Sep 1, 4:12 PM EDTRiver Flood WarningPHICarbon15 hr
Sep 1, 4:13 PM EDTTornado WarningPHIChester32 min
Sep 1, 4:20 PM EDTRiver Flood WarningPHIMontgomery22 hr
Sep 1, 4:21 PM EDTRiver Flood WarningPHIBucks29 hr
Sep 1, 4:42 PM EDTFlash Flood Warning EmergencyConsiderable damage threatPHIChester, Delaware, Montgomery6 hr
Sep 1, 5:07 PM EDTRiver Flood WarningPHIChester17 hr
Sep 1, 5:13 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia47 min
Sep 1, 5:15 PM EDTTornado WarningPHIDelaware, Montgomery, Philadelphia30 min
Sep 1, 5:26 PM EDTFlash Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia9 hr
Sep 1, 5:34 PM EDTTornado WarningPHIBucks, Montgomery, Philadelphia26 min
Sep 1, 5:42 PM EDTFlash Flood WarningPHIBucks10 hr
Sep 1, 5:57 PM EDTTornado WarningPHIBucks33 min
Sep 1, 6:08 PM EDTFlash Flood WarningPHIMonroe, Northampton6 hr
Sep 1, 6:20 PM EDTTornado WarningPHIBucks40 min
Sep 1, 6:22 PM EDTTornado Warning Tornado observedPHIPhiladelphia23 min
Sep 1, 6:38 PM EDTRiver Flood WarningPHIChester, Delaware26 hr
Sep 1, 6:42 PM EDTTornado WarningPHIBucks, Philadelphia33 min
Sep 1, 6:59 PM EDTSevere Thunderstorm WarningPHIBucks61 min
Sep 1, 7:04 PM EDTTornado Warning EmergencyTornado observedCatastrophic damage threatPHIBucks26 min
Sep 1, 7:05 PM EDTFlash Flood Warning EmergencyCatastrophic damage threatPHIBucks8 hr
Sep 1, 7:22 PM EDTTornado WarningPHIBucks11 min
Sep 1, 7:23 PM EDTAreal Flood WarningPHIBerks, Lehigh14 hr
Sep 1, 7:31 PM EDTFlash Flood Warning EmergencyCatastrophic damage threatPHIBucks4 hr
Sep 1, 7:53 PM EDTRiver Flood WarningPHIDelaware13 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2021Every flash flood warning in 2021

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.