Alert archive / Pennsylvania / Flash Flood Warnings in 2019

Flash Flood Warning 85, NWS Philadelphia/Mount Holly

October 31, 20196 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Oct 31, 2019, 11:08 PM EDT for 6 counties in Pennsylvania. It was in force for 4 hr. 6 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
Oct 31, 2019, 11:08 PM EDT (03:08 UTC)
Expired
Nov 1, 2019, 3:15 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Berks County, PA, Bucks County, PA, Chester County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 109 km from the middle of the area, began a volume at 03:11 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
Oct 31, 11:30 PM EDTFLASH FLOOD1 S Bethlehem Twp, PAWILLOW PARK ROAD CLOSED FROM FLASH FLOODING.
Oct 31, 11:31 PM EDTFLASH FLOOD1 Ese Allentown, PAWATER RESCUE IN PROGRESS ON BASIN STREET.
Nov 1, 12:00 AM EDTFLASH FLOOD2 Ene Steuben, PAFLASH FLOODING ON NEWBURG ROAD NEAR ROUTE 191 WITH ROADS CLOSED.
Nov 1, 12:15 AM EDTFLASH FLOOD1 Sse Coopersburg, PAFLASH FLOODING CLOSED PORTIONS OF STATE HIGHWAY 309 IN SPRINGFIELD TWP.
Nov 1, 1:15 AM EDTFLASH FLOODPerkiomen Creek At East, PATHE GAUGE ON PERKIOMEN CREEK AT EAST GREENVILLE REACHED MINOR FLOOD STAGE.
Nov 1, 2:01 AM EDTFLASH FLOOD2 Se Honey Brook Twp, PATHE WEST BRANCH BRANDYWINE CREEK GAUGE AT HONEY BROOK REACHED MINOR FLOOD STAGE.

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 00:00Z, 3.1 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 00:00Z on 2019-11-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 529 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 00:00Z on 2019-11-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 623 square meters per square second.1939587897Sfc1 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
529 J/kg
Mixed-layer CIN
-20 J/kg
Mixed-layer LCL
827 m above ground
0-6 km bulk shear
72 kt
0-1 km storm-relative helicity
623 m²/s²
0-3 km storm-relative helicity
752 m²/s²
Significant tornado parameter
2.5
Supercell composite
9.8

Open this sounding in Storm Lab

The text

As transmitted.

607 
WGUS51 KPHI 010308
FFWPHI
PAC011-017-029-077-091-095-010715-
/O.NEW.KPHI.FF.W.0085.191101T0308Z-191101T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1108 PM EDT Thu Oct 31 2019

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Eastern Berks County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  Lehigh County in eastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...
  Southwestern Northampton County in eastern Pennsylvania...

* Until 315 AM EDT.

* At 1108 PM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Flash flooding is expected to
  begin shortly in the areas of heaviest rain.

* Some locations that could experience flooding include...
  Allentown, Reading, Easton, West Chester, Bethlehem, Norristown,
  Pottstown, Phoenixville, Lansdale, West Norriton, East Norriton,
  Coatesville, Emmaus, Northampton, Quakertown, Perkasie, Doylestown,
  Byram, Wilson and Downingtown.

This includes Interstate 78 in Pennsylvania between mile markers 45
and 76.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3976 7606 3987 7599 3995 7600 4004 7593
      4011 7594 4014 7588 4023 7601 4057 7575
      4083 7541 4066 7519 4057 7519 4058 7512
      4054 7507 4045 7507 4040 7504 3972 7582
      3972 7613

$$

CMS
4 follow-up statements
285 
WGUS71 KPHI 010347
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1147 PM EDT Thu Oct 31 2019

PAC011-017-029-077-091-095-010715-
/O.CON.KPHI.FF.W.0085.000000T0000Z-191101T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Montgomery PA-Lehigh PA-Bucks PA-Chester PA-Northampton PA-
1147 PM EDT Thu Oct 31 2019

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 AM EDT FOR
EASTERN BERKS...MONTGOMERY...LEHIGH...NORTHWESTERN BUCKS...CHESTER
AND SOUTHWESTERN NORTHAMPTON COUNTIES...

At 1146 PM EDT, local law enforcement reported flash flooding in the 
Allentown area. Several reports of street flooding have also been 
received from Pottstown. Flash flooding will continue for the next 
few hours.

Some locations that could experience flooding include...
Allentown, Reading, Easton, West Chester, Bethlehem, Norristown,
Pottstown, Phoenixville, Lansdale, West Norriton, East Norriton,
Coatesville, Emmaus, Northampton, Quakertown, Perkasie, Doylestown,
Byram, Wilson and Downingtown.

This includes Interstate 78 in Pennsylvania between mile markers 45
and 76.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3976 7606 3987 7599 3995 7600 4004 7593
      4011 7594 4014 7588 4023 7601 4057 7575
      4083 7541 4066 7519 4057 7519 4058 7512
      4054 7507 4045 7507 4040 7504 3972 7582
      3972 7613

$$

CMS
434 
WGUS71 KPHI 010518
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
118 AM EDT Fri Nov 1 2019

PAC011-017-029-077-091-095-010715-
/O.CON.KPHI.FF.W.0085.000000T0000Z-191101T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Montgomery PA-Lehigh PA-Bucks PA-Chester PA-Northampton PA-
118 AM EDT Fri Nov 1 2019

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 AM EDT FOR
EASTERN BERKS...MONTGOMERY...LEHIGH...NORTHWESTERN BUCKS...CHESTER
AND SOUTHWESTERN NORTHAMPTON COUNTIES...

At 116 AM EDT, local law enforcement reported flash flooding in 
Allentown and Bethlehem. Additionally, several streams are rising 
rapidly in western Bucks and western Montgomery Counties. Even 
though the heaviest rainfall has ended, flash flooding will continue 
for the next few hours.

Some locations that could experience flooding include...
Allentown, Reading, Easton, West Chester, Bethlehem, Norristown,
Pottstown, Phoenixville, Lansdale, West Norriton, East Norriton,
Coatesville, Emmaus, Northampton, Quakertown, Perkasie, Doylestown,
Byram, Wilson and Downingtown.

This includes Interstate 78 in Pennsylvania between mile markers 45
and 76.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3976 7606 3987 7599 3995 7600 4004 7593
      4011 7594 4014 7588 4023 7601 4057 7575
      4083 7541 4066 7519 4057 7519 4058 7512
      4054 7507 4045 7507 4040 7504 3972 7582
      3972 7613

$$

CMS
674 
WGUS71 KPHI 010622
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
222 AM EDT Fri Nov 1 2019

PAC011-017-029-077-091-095-010715-
/O.CON.KPHI.FF.W.0085.000000T0000Z-191101T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Montgomery PA-Lehigh PA-Bucks PA-Chester PA-Northampton PA-
222 AM EDT Fri Nov 1 2019

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 AM EDT FOR
EASTERN BERKS...MONTGOMERY...LEHIGH...NORTHWESTERN BUCKS...CHESTER
AND SOUTHWESTERN NORTHAMPTON COUNTIES...

At 219 AM EDT, automated gauges on the Perkiomen Creek in East 
Greenville and the West Branch Brandywine Creek at Honey Brook 
indicate levels have reached flood stage. Flash flooding is expected 
to continue across the warned area.

Some locations that could experience flooding include...
Allentown, Reading, Easton, West Chester, Bethlehem, Norristown,
Pottstown, Phoenixville, Lansdale, West Norriton, East Norriton,
Coatesville, Emmaus, Northampton, Quakertown, Perkasie, Doylestown,
Byram, Wilson and Downingtown.

This includes Interstate 78 in Pennsylvania between mile markers 45
and 76.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3976 7606 3987 7599 3995 7600 4004 7593
      4011 7594 4014 7588 4023 7601 4057 7575
      4083 7541 4066 7519 4057 7519 4058 7512
      4054 7507 4045 7507 4040 7504 3972 7582
      3972 7613

$$

CMS
217 
WGUS71 KPHI 010707
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
307 AM EDT Fri Nov 1 2019

PAC011-017-029-077-091-095-010716-
/O.EXP.KPHI.FF.W.0085.000000T0000Z-191101T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Montgomery PA-Lehigh PA-Bucks PA-Chester PA-Northampton PA-
307 AM EDT Fri Nov 1 2019

...THE FLASH FLOOD WARNING FOR EASTERN BERKS...MONTGOMERY...LEHIGH...
NORTHWESTERN BUCKS...CHESTER AND SOUTHWESTERN NORTHAMPTON COUNTIES
WILL EXPIRE AT 315 AM EDT...

An areal flood warning has been issued for this area until 700 am. 
Please continue to heed any road closures.

LAT...LON 3976 7606 3987 7599 3995 7600 4004 7593
      4011 7594 4014 7588 4023 7601 4057 7575
      4083 7541 4066 7519 4057 7519 4058 7512
      4054 7507 4045 7507 4040 7504 3972 7582
      3972 7613

$$

CMS

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 31, 8:11 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh64 min
Oct 31, 8:58 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Monroe, Northampton62 min
Oct 31, 9:35 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Montgomery55 min
Oct 31, 9:41 PM EDTFlash Flood WarningPHIBerks4 hr
Oct 31, 9:56 PM EDTAreal Flood AdvisoryPHICarbon, Monroe4 hr
Oct 31, 9:56 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton64 min
Oct 31, 10:23 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Montgomery67 min
Oct 31, 10:43 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton77 min
Oct 31, 10:45 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Chester, Lehigh, Montgomery, Northampton4 hr
Oct 31, 11:14 PM EDTFlash Flood WarningPHICarbon, Monroe, Northampton4 hr
Oct 31, 11:15 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia60 min
Oct 31, 11:32 PM EDTTornado WarningPHIChester, Delaware, Montgomery, Philadelphia14 min
Oct 31, 11:54 PM EDTSevere Thunderstorm WarningPHIBucks66 min
Oct 31, 11:54 PM EDTTornado WarningPHIBucks36 min
Nov 1, 1:43 AM EDTAreal Flood WarningPHIBerks4 hr
Nov 1, 2:28 AM EDTRiver Flood WarningPHIChester4 hr
Nov 1, 3:02 AM EDTAreal Flood WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery, Northampton5 hr
Nov 1, 3:06 AM EDTAreal Flood WarningPHICarbon, Monroe, Northampton4 hr
Nov 1, 3:31 AM EDTFreeze WatchPHIBerks, Bucks, Chester, Lehigh, Montgomery, Northampton6 hr
Nov 1, 9:12 AM EDTFreeze WarningPHIBerks, Bucks, Chester, Delaware, Lehigh, Montgomery and 1 more25 hr
Nov 1, 3:16 PM EDTFrost AdvisoryPHIPhiladelphia19 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2019Every flash flood warning in 2019

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.