Alert archive / Pennsylvania / Flash Flood Warnings in 2021

Flash Flood Warning 1, NWS Philadelphia/Mount Holly

June 3, 2021Berks County, Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 3, 2021, 5:59 PM EDT for Berks County, Chester County, Pennsylvania. It was in force for 108 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 3, 2021, 5:59 PM EDT (21:59 UTC)
Expired: Jun 3, 2021, 7:47 PM EDT
In force: 108 min
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 22:01 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, 10.0 hours before the alert went out and 185 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 73 J/kg
Mixed-layer CIN: -52 J/kg
Mixed-layer LCL: 511 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 116 m²/s²
0-3 km storm-relative helicity: 118 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

628 
WGUS51 KPHI 032159
FFWPHI
PAC011-029-040100-
/O.NEW.KPHI.FF.W.0001.210603T2159Z-210604T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
559 PM EDT Thu Jun 3 2021

The National Weather Service in Mount Holly has issued a

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

* Until 900 PM EDT.

* At 559 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1.5 and 2 inches of 
  rain have fallen. Flash flooding is ongoing or expected to begin 
  shortly. Some additional rainfall is expected.

  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...
  Honey Brook, Elverson, New Morgan, and Glenmoore.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 296 and 307.
	Interstate 176 in Pennsylvania between mile markers 1 and 2.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Motorists should not attempt to drive around barricades or drive 
cars through flooded areas.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 4014 7588 4014 7587 4016 7590 4016 7592
      4017 7593 4023 7584 4024 7576 4021 7569
      4008 7574 4001 7595 4004 7593 4006 7594
      4008 7594 4009 7594 4011 7594 4011 7593
      4012 7592

FLASH FLOOD...RADAR INDICATED

$$

NC

1 follow-up statement

130 
WGUS71 KPHI 032347
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
747 PM EDT Thu Jun 3 2021

PAC011-029-032357-
/O.CAN.KPHI.FF.W.0001.000000T0000Z-210604T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Chester PA-
747 PM EDT Thu Jun 3 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTH CENTRAL BERKS AND 
NORTH CENTRAL CHESTER COUNTIES...

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

A separate and larger flash flood warning remains in effect for 
Chester county.

A Flash Flood Watch remains in effect until 1000 PM EDT for portions 
of northern Delaware...southern New Jersey...and southeast 
Pennsylvania.

LAT...LON 4014 7588 4014 7587 4016 7590 4016 7592
      4017 7593 4023 7584 4024 7576 4021 7569
      4008 7574 4001 7595 4004 7593 4006 7594
      4008 7594 4009 7594 4011 7594 4011 7593
      4012 7592

$$

NC

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 3, 9:37 AM EDT	Flash Flood Watch	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	12 hr
Jun 3, 3:02 PM EDT	Special Weather Statement	PHI	Berks	43 min
Jun 3, 3:54 PM EDT	Special Weather Statement	PHI	Berks	36 min
Jun 3, 5:14 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester	27 min
Jun 3, 5:20 PM EDT	Areal Flood Advisory	PHI	Berks, Chester, Delaware, Montgomery, Philadelphia	3 hr
Jun 3, 6:19 PM EDT	Flash Flood Warning	PHI	Berks, Chester, Montgomery	115 min
Jun 3, 7:09 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	2 hr
Jun 3, 7:13 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	3 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2021 Every 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.