Alert archive / Pennsylvania / Flash Flood Warnings in 2021

Flash Flood Warning 6, NWS Philadelphia/Mount Holly

June 8, 2021Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 8, 2021, 3:21 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 3 hr. 27 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 8, 2021, 3:21 PM EDT (19:21 UTC)
Expired: Jun 8, 2021, 6:28 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 127 km from the middle of the area, began a volume at 19:24 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

Time	Report	Where	Remark
Jun 8, 3:50 PM EDT	FLASH FLOOD	1 Nne South Coatesville, PA	VEHICLE FLOODED OUT ON FOUNDRY ST NEAR 11TH AVE. ALL OCCUPANTS WERE REMOVED SAFELY.
Jun 8, 4:00 PM EDT	FLASH FLOOD	Coatesville, PA	WATER RESCUE ON FLEETWOOD ST AT 4TH AVE.
Jun 8, 4:00 PM EDT	FLASH FLOOD	Coatesville, PA	WATER RESCUE ON OLIVE ST AT 5TH AVE.
Jun 8, 4:00 PM EDT	FLASH FLOOD	Thorndale, PA	WATER RESCUE ON HAZELWOOD AVE NEAR LINCOLN HWY.
Jun 8, 4:10 PM EDT	FLASH FLOOD	1 E Thorndale, PA	WATER RESCUE NEAR THE INTERSECTION OF W LANCASTER AVE AND S LLOYD AVE.
Jun 8, 4:10 PM EDT	FLASH FLOOD	1 Nne Coatesville, PA	WATER RESCUE NEAR THE INTERSECTION ON MANOR RD AND BUTTERWORTH RD.
Jun 8, 4:11 PM EDT	FLASH FLOOD	Coatesville, PA	LINCOLN HWY CLOSED DUE TO FLOODING.
Jun 8, 4:15 PM EDT	FLASH FLOOD	2 Ne South Coatesville, PA	WATER RESCUE NEAR THE INTERSECTION OF S CALN RD AND LINCOLN HWY.
Jun 8, 4:15 PM EDT	FLASH FLOOD	Coatesville, PA	1ST AVE AT LUMBER ST FLOODED AND CLOSED.
Jun 8, 4:20 PM EDT	FLASH FLOOD	1 Wsw Parkesburg, PA	LOWER VALLEY RD NEAR 6TH AVE FLOODED DUE TO THE NEARBY CREEK OVERFLOWING ITS BANKS. FLOOD WATERS ALSO CAUSED A TREE TO FALL.
Jun 8, 4:20 PM EDT	FLASH FLOOD	2 Ne Coatesville, PA	BLACKHORSE HILL RD FLOODED AND CLOSED NEAR NEW JERSEY AVE.
Jun 8, 4:30 PM EDT	FLASH FLOOD	1 Ssw Coatesville, PA	WATER RESCUE ON FEDERAL ST AT STRODE AVE.
Jun 8, 4:30 PM EDT	FLASH FLOOD	2 Ne South Coatesville, PA	N CALN RD FLOODED AND CLOSED.
Jun 8, 4:35 PM EDT	FLASH FLOOD	1 Wnw Caln Twp, PA	A LANDSLIDE BLOCKED WESTBOUND ROUTE 30 NEAR KINGS HWY.
Jun 8, 4:40 PM EDT	FLASH FLOOD	2 Se Sadsburyville, PA	WATER RESCUE NEAR THE INTERSECTION OF CYNTHIA RD AND MARC DR.
Jun 8, 4:45 PM EDT	FLASH FLOOD	1 Nw Caln Twp, PA	FLOODING NEAR THE INTERSECTION OF CALN MEETINGHOUSE RD AND FISHERVILLE RD. CALLED IN BY A SCHOOL BUS DRIVER WHO STOPPED SHORT OF THE FLOODWATERS BUT WAS UNABLE TO TURN AROUND DUE TO TRAFFIC.
Jun 8, 5:00 PM EDT	FLASH FLOOD	1 Ssw Valley Twp, PA	WATER RESCUE ON N PARK AVE AT VALLEY RD.
Jun 8, 5:02 PM EDT	FLASH FLOOD	1 Nw Coatesville, PA	THE GAUGE ALONG THE WEST BRANCH OF THE BRANDYWINE CREEK AT COATESVILLE REACHED MINOR FLOOD STAGE.
Jun 8, 5:05 PM EDT	FLASH FLOOD	1 Ne Caln Twp, PA	PHOTO WITH FLOOD WATERS OVER A FOOT DEEP AT THE INTERSECTION OF PA 340 AND US 30.
Jun 8, 5:10 PM EDT	FLASH FLOOD	1 N East Brandywine Twp, PA	A COUPLE OF VEHICLES STRANDED NEAR THE INTERSECTION OF LITTLE WASHINGTON RD AND N GUTHRIESVILLE RD.
Jun 8, 5:50 PM EDT	FLASH FLOOD	Thorndale, PA	WATER RESCUE ON G O CARSON BLVD AT BONDSVILLE RD.
Jun 8, 5:55 PM EDT	FLASH FLOOD	Downington, PA	WATER RESCUE NEAR THE INTERSECTION OF JEFFERSON AVE AND GREEN ST.
Jun 8, 5:55 PM EDT	HEAVY RAIN 3	West Caln Twp, PA
Jun 8, 6:14 PM EDT	HEAVY RAIN 5.53	2 Nw Marshallton, PA	PERSONAL WEATHER STATION KPAWESTC93.
Jun 8, 6:15 PM EDT	HEAVY RAIN 5.87	2 Ssw West Bradford Twp, PA	PERSONAL WEATHER STATION KPACOATE73.
Jun 8, 6:16 PM EDT	HEAVY RAIN 7.16	1 E Modena, PA	PERSONAL WEATHER STATION KPAEASTF8. THIS IS THE MAXIMUM RAINFALL AMOUNT WE HAVE SEEN AND CORRESPONDS WELL TO RADAR ESTIMATES.
Jun 8, 6:20 PM EDT	FLASH FLOOD	Downington, PA	FLOODING ON JEFFERSON AVE AT BRANDYWINE AVE. WATER THREATENING HOUSES.

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, 7.4 hours before the alert went out and 169 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: 254 J/kg
Mixed-layer CIN: -121 J/kg
Mixed-layer LCL: 1088 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -39 m²/s²
0-3 km storm-relative helicity: 23 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

038 
WGUS51 KPHI 081921
FFWPHI
PAC029-091-082330-
/O.NEW.KPHI.FF.W.0006.210608T1921Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
321 PM EDT Tue Jun 8 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Chester County in southeastern Pennsylvania...
  West Central Montgomery County in southeastern Pennsylvania...

* Until 730 PM EDT.

* At 321 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 1 to 2 inches 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...
  West Chester, Pottstown, Phoenixville, West Norriton, Coatesville, 
  Downingtown, Collegeville, Oxford, Royersford, Parkesburg, Trappe, 
  and West Grove.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 301 and 323.

This includes the following streams and drainages...
  Schuylkill, Chester-Sassafras, Lower Delaware, Lower Susquehanna, 
  and Brandywine-Christina.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4024 7570 4035 7561 4015 7537 3983 7579
      3979 7572 3972 7577 3972 7612 3976 7608
      3976 7606 3983 7604 3983 7602 3985 7602
      3985 7601 3987 7600 3987 7599 3993 7600
      3993 7598 3995 7599 4004 7594 4011 7594

FLASH FLOOD...RADAR INDICATED

$$

Iovino

2 follow-up statements

532 
WGUS71 KPHI 082011
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
411 PM EDT Tue Jun 8 2021

PAC091-082021-
/O.CAN.KPHI.FF.W.0006.000000T0000Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-
411 PM EDT Tue Jun 8 2021

...FLASH FLOOD WARNING IS CANCELLED FOR WEST CENTRAL MONTGOMERY 
COUNTY...

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

LAT...LON 4024 7567 4022 7561 4024 7560 4015 7552
      4016 7550 4014 7551 4012 7546 4009 7546
      4009 7545 3983 7579 3979 7572 3972 7577
      3972 7612 3976 7606 3983 7604 3987 7599
      3993 7600 3993 7598 4004 7593 4011 7594

$$

PAC029-082330-
/O.CON.KPHI.FF.W.0006.000000T0000Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
411 PM EDT Tue Jun 8 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM EDT THIS 
EVENING FOR CHESTER COUNTY...

At 411 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 4 inches of rain have 
fallen. Additional rainfall amounts of 0.5 to 1.5 inches are 
possible in the warned area. Flash flooding is ongoing or expected 
to begin shortly.

HAZARD...Life threatening flash flooding caused by thunderstorms.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets, and underpasses.

Some locations that will experience flash flooding include...
  West Chester, Phoenixville, Coatesville, Downingtown, Oxford, 
  Parkesburg, West Grove, Honey Brook, Elverson, Marshallton, 
  Glenmoore, and Lionville.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 301 and 323.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4024 7567 4022 7561 4024 7560 4015 7552
      4016 7550 4014 7551 4012 7546 4009 7546
      4009 7545 3983 7579 3979 7572 3972 7577
      3972 7612 3976 7606 3983 7604 3987 7599
      3993 7600 3993 7598 4004 7593 4011 7594

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Iovino

778 
WGUS71 KPHI 082228
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
628 PM EDT Tue Jun 8 2021

PAC029-082238-
/O.CAN.KPHI.FF.W.0006.000000T0000Z-210608T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
628 PM EDT Tue Jun 8 2021

...FLASH FLOOD WARNING IS CANCELLED FOR CHESTER COUNTY...

The heavy rain has ended but significant flooding continues in the 
Brandywine Creek basin. A Flood Warning is in effect for the 
Brandywine Creek basin in Chester County and far western Delaware 
County until 8:00 AM on Wednesday. Do not drive on flooded roadways.

LAT...LON 4024 7567 4022 7561 4024 7560 4015 7552
      4016 7550 4014 7551 4012 7546 4009 7546
      4009 7545 3983 7579 3979 7572 3972 7577
      3972 7612 3976 7606 3983 7604 3987 7599
      3993 7600 3993 7598 4004 7593 4011 7594

$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 8, 11:54 AM EDT	Areal Flood Advisory	PHI	Monroe	2 hr
Jun 8, 12:34 PM EDT	Flash Flood Warning	PHI	Monroe	2 hr
Jun 8, 12:40 PM EDT	Special Weather Statement	PHI	Monroe	35 min
Jun 8, 1:09 PM EDT	Special Weather Statement	PHI	Monroe	21 min
Jun 8, 1:17 PM EDT	Special Weather Statement	PHI	Chester	13 min
Jun 8, 1:18 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware, Montgomery, Philadelphia	3 hr
Jun 8, 1:24 PM EDT	Special Weather Statement	PHI	Delaware	21 min
Jun 8, 1:27 PM EDT	Areal Flood Advisory	PHI	Carbon, Lehigh, Monroe, Northampton	3 hr
Jun 8, 1:35 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery	5 hr
Jun 8, 2:07 PM EDT	Special Weather Statement	PHI	Bucks	23 min
Jun 8, 2:19 PM EDT	Areal Flood Advisory	PHI	Bucks	2 hr
Jun 8, 2:43 PM EDT	Special Weather Statement	PHI	Montgomery	32 min
Jun 8, 3:15 PM EDT	Special Weather Statement	PHI	Chester	30 min
Jun 8, 3:43 PM EDT	Special Weather Statement	PHI	Chester	32 min
Jun 8, 4:20 PM EDT	Special Weather Statement	PHI	Chester	25 min
Jun 8, 4:25 PM EDT	River Flood Warning	PHI	Chester	11 hr
Jun 8, 6:21 PM EDT	Areal Flood Warning	PHI	Chester, Delaware	15 hr
Jun 8, 7:14 PM EDT	River Flood Warning	PHI	Chester, Delaware	18 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.