Alert archive / Pennsylvania / Flash Flood Warnings in 2021

Flash Flood Warning 9, NWS Philadelphia/Mount Holly

June 9, 2021Berks County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 9, 2021, 4:54 PM EDT for Berks County, Montgomery County, Pennsylvania. It was in force for 112 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
Jun 9, 2021, 4:54 PM EDT (20:54 UTC)
Expired
Jun 9, 2021, 6:46 PM EDT
In force
112 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Berks County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 115 km from the middle of the area, began a volume at 20:57 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, 8.9 hours before the alert went out and 225 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 2021-06-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 193 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 2021-06-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -75 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
193 J/kg
Mixed-layer CIN
-128 J/kg
Mixed-layer LCL
1225 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
-75 m²/s²
0-3 km storm-relative helicity
3 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

504 
WGUS51 KPHI 092054
FFWPHI
PAC011-091-092345-
/O.NEW.KPHI.FF.W.0009.210609T2054Z-210609T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
454 PM EDT Wed Jun 9 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  East Central Berks County in eastern Pennsylvania...
  Northwestern Montgomery County in southeastern Pennsylvania...

* Until 745 PM EDT.

* At 454 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 0.5 to 1 inch are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  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 will experience flash flooding include...
  Kutztown, Fleetwood, East Greenville, Topton, Bally, 
  Bechtelsville, Lyons, Gilbertsville, Geryville, Boyertown, 
  Pennsburg, and Red Hill.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4028 7569 4032 7585 4050 7594 4055 7580
      4052 7565 4052 7564 4050 7562 4050 7561
      4049 7560 4048 7558 4045 7553 4043 7550
      4042 7548 4041 7547 4040 7546 4038 7543
      4038 7542

FLASH FLOOD...RADAR INDICATED

$$

NC
2 follow-up statements
887 
WGUS71 KPHI 092148
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
548 PM EDT Wed Jun 9 2021

PAC091-092158-
/O.CAN.KPHI.FF.W.0009.000000T0000Z-210609T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-
548 PM EDT Wed Jun 9 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN MONTGOMERY 
COUNTY...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

LAT...LON 4028 7569 4032 7585 4050 7594 4055 7580
      4052 7565 4050 7562 4050 7561 4045 7553
      4029 7566

$$

PAC011-092345-
/O.CON.KPHI.FF.W.0009.000000T0000Z-210609T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
548 PM EDT Wed Jun 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 745 PM EDT THIS 
EVENING FOR EAST CENTRAL BERKS COUNTY...

At 548 PM EDT, Doppler radar and automated rain gauges indicated 
thunderstorms have produced heavy rain across the warned area. 
Between 1.5 and 3 inches of rain have fallen. Flash flooding is 
ongoing or expected to begin shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar and automated gauges.

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 will experience flash flooding include...
  Kutztown, Fleetwood, Topton, Bally, Bechtelsville, Lyons, and 
  Boyertown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4028 7569 4032 7585 4050 7594 4055 7580
      4052 7565 4050 7562 4050 7561 4045 7553
      4029 7566

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

NC
268 
WGUS71 KPHI 092246
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
646 PM EDT Wed Jun 9 2021

PAC011-092256-
/O.CAN.KPHI.FF.W.0009.000000T0000Z-210609T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
646 PM EDT Wed Jun 9 2021

...FLASH FLOOD WARNING IS CANCELLED FOR EAST CENTRAL BERKS COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4028 7569 4032 7585 4050 7594 4055 7580
      4052 7565 4050 7562 4050 7561 4045 7553
      4029 7566

$$

NC

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 9, 3:49 PM EDTFlash Flood WarningPHIBucks, Philadelphia3 hr
Jun 9, 5:27 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh, Northampton23 min
Jun 9, 5:32 PM EDTSevere Thunderstorm WarningPHIBucks28 min

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.