Alert archive / Pennsylvania / Flash Flood Warnings in 2021

Flash Flood Warning 26, NWS State College, PA

September 1, 202116 counties in Pennsylvania

NWS State College, PA issued this flash flood warning at Sep 1, 2021, 12:04 PM EDT for 16 counties in Pennsylvania. It was in force for 6 hr. 15 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, 12:04 PM EDT (16:04 UTC)
Expired
Sep 1, 2021, 5:41 PM EDT
In force
6 hr
Issued by
NWS State College, PA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Adams County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Schuylkill County, PA, Snyder County, PA, Union County, PA, York County, PA

The radar

The State College radar (KCCX), 109 km from the middle of the area, began a volume at 16:04 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, 1:42 PM EDTHEAVY RAIN 2.351 Nw Stonybrook, PA
Sep 1, 1:55 PM EDTHEAVY RAIN 3Shiremanstown, PA3.00 INCHES OF RAIN SINCE 6AM.
Sep 1, 2:00 PM EDTFLASH FLOOD1 Sse Harrisburg, PAWATER RESCUES ONGOING IN HARRISBURG.
Sep 1, 2:04 PM EDTHEAVY RAIN 3.6Greencastle, PA3.6 INCHES OF RAIN REPORTED IN GREENCASTLE. TRAINED SPOTTER.
Sep 1, 2:14 PM EDTFLASH FLOOD1 Wnw Lancaster, PAWATER RESCUE NEAR F&M COLLEGE. PER LANCASTER CO 911.
Sep 1, 3:08 PM EDTFLASH FLOODLinntown, PA1 FT OF WATER ACROSS THE ROAD. MULTIPLE OTHER CREEKS NEAR BANK HEIGHT.
Sep 1, 3:15 PM EDTFLASH FLOOD2 Sw Lititz, PAWATER RESCUE.
Sep 1, 3:32 PM EDTHEAVY RAIN 51 E Herndon, PA
Sep 1, 3:34 PM EDTFLASH FLOOD2 E Williamstown, PAROAD CLOSED DUE TO FLOODING.
Sep 1, 4:05 PM EDTHEAVY RAIN 5Shiremanstown, PA5 INCHES OF RAIN REPORTED IN SHIREMANSTOWN.
Sep 1, 4:09 PM EDTFLASH FLOODShiremanstown, PAROAD CLOSED DUE TO FLOODING.
Sep 1, 4:14 PM EDTFLASH FLOODPalmyra, PAWATER RESCUE IN THE 200 BLOCK OF EAST CHERRY STREET.
Sep 1, 4:30 PM EDTFLASH FLOOD3 Se Lawn, PALITTLE CHIQUIES CREEK SIGNIFICANTLY OVERTOPPED ELIZABETHTOWN ROAD.
Sep 1, 5:30 PM EDTFLASH FLOOD1 Sse York, PASIGNIFICANT FLOODING ALONG TYLER RUN CREEK IN THE VICINITY OF YORK COLLEGE.
Sep 1, 5:46 PM EDTFLASH FLOOD1 Se Newmanstown, PAVEHICLE IN FLOOD WATERS WITH POSSIBLE RESCUE AT SOUTH ZELLERS ROAD AND SOUTH SHERIDAN ROAD IN MILLCREEK TOWNSHIP.

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, 4.1 hours before the alert went out and 186 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°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.

715 
WGUS51 KCTP 011604
FFWCTP
PAC001-037-041-043-055-067-071-075-087-093-097-099-107-109-119-133-
012200-
/O.NEW.KCTP.FF.W.0026.210901T1604Z-210901T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service State College PA
1204 PM EDT Wed Sep 1 2021

The National Weather Service in State College has issued a

* Flash Flood Warning for...
  Columbia County in central Pennsylvania...
  Juniata County in central Pennsylvania...
  Mifflin County in central Pennsylvania...
  Montour County in central Pennsylvania...
  Northumberland County in central Pennsylvania...
  Schuylkill County in central Pennsylvania...
  Snyder County in central Pennsylvania...
  Union County in central Pennsylvania...
  Adams County in south central Pennsylvania...
  Cumberland County in south central Pennsylvania...
  Dauphin County in south central Pennsylvania...
  Franklin County in south central Pennsylvania...
  Lancaster County in south central Pennsylvania...
  Lebanon County in south central Pennsylvania...
  Perry County in south central Pennsylvania...
  York County in south central Pennsylvania...

* Until 600 PM EDT.

* At 1204 PM EDT, Doppler radar and automated rain gauges indicated 
  heavy rain falling across the warned area. Between 1 and 3 inches 
  of rain have fallen. The expected rainfall rate is 0.75 to 1.25 
  inches in 1 hour. Additional rainfall amounts of 1 to 3 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Life threatening flash flooding. Heavy rain producing
           flash flooding.

  SOURCE...Radar and automated gauges.

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

* Some locations that will experience flash flooding include...
  Lancaster, Harrisburg, York, Lebanon, Chambersburg, Carlisle, 
  Lower Allen, Hanover, Bloomsburg, Pottsville, Hershey, Ephrata, 
  Colonial Park, Weigelstown, Elizabethtown, Waynesboro, Berwick, 
  Columbia, Sunbury and Progress.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4040 7791 4058 7782 4073 7768 4085 7737
      4115 7696 4116 7659 4131 7641 4131 7631
      4095 7621 4091 7600 4074 7576 4057 7602
      4050 7644 4014 7588 4011 7594 3987 7599
      3972 7610 3972 7810 4026 7770 4038 7775

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.75-1.25 INCHES IN 1 HOUR

$$

Lambert/Ross
1 follow-up statement
454 
WGUS71 KCTP 012141
FFSCTP

Flash Flood Statement
National Weather Service State College PA
541 PM EDT Wed Sep 1 2021

PAC001-037-041-043-055-067-071-075-087-093-097-099-107-109-119-133-
012151-
/O.CAN.KCTP.FF.W.0026.000000T0000Z-210901T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Adams PA-Columbia PA-Cumberland PA-Dauphin PA-Franklin PA-Juniata PA-
Lancaster PA-Lebanon PA-Mifflin PA-Montour PA-Northumberland PA-
Perry PA-Schuylkill PA-Snyder PA-Union PA-York PA-
541 PM EDT Wed Sep 1 2021

...FLASH FLOOD WARNING FOR COLUMBIA, JUNIATA, MIFFLIN, MONTOUR, 
NORTHUMBERLAND, SCHUYLKILL, SNYDER, UNION, ADAMS, CUMBERLAND, 
DAUPHIN, FRANKLIN, LANCASTER, LEBANON, PERRY AND YORK COUNTIES HAS 
BEEN REPLACED WITH A FLOOD WARNING...

LAT...LON 4040 7791 4058 7782 4073 7768 4085 7737
      4115 7696 4116 7659 4131 7641 4131 7631
      4095 7621 4091 7600 4074 7576 4057 7602
      4050 7644 4014 7588 4011 7594 3987 7599
      3972 7610 3972 7810 4026 7770 4038 7775

$$

CR

The office that day

Everything else NWS State College, PA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 1, 8:54 AM EDTFlash Flood Warning Considerable damage threatCTPBedford, Blair, Cambria, Centre, Clearfield, Fulton and 3 more8 hr
Sep 1, 9:37 AM EDTFlash Flood Warning Considerable damage threatCTPCambria, Clearfield, Somerset6 hr
Sep 1, 9:45 AM EDTAreal Flood AdvisoryCTPAdams, Columbia, Cumberland, Dauphin, Franklin, Juniata and 10 more2 hr
Sep 1, 11:04 AM EDTRiver Flood WarningCTPSnyder, Union17 hr
Sep 1, 11:04 AM EDTRiver Flood WarningCTPCambria17 hr
Sep 1, 11:04 AM EDTRiver Flood WarningCTPHuntingdon23 hr
Sep 1, 11:04 AM EDTRiver Flood WarningCTPJuniata, Mifflin20 hr
Sep 1, 11:04 AM EDTRiver Flood WarningCTPBedford, Huntingdon30 hr
Sep 1, 11:04 AM EDTRiver Flood WarningCTPDauphin55 hr
Sep 1, 1:09 PM EDTFlash Flood Warning EmergencyCatastrophic damage threatCTPCambria5 hr
Sep 1, 2:07 PM EDTSevere Thunderstorm WarningCTPAdams53 min
Sep 1, 2:28 PM EDTSevere Thunderstorm WarningCTPYork77 min
Sep 1, 3:05 PM EDTTornado WarningCTPYork23 min
Sep 1, 3:25 PM EDTSevere Thunderstorm WarningCTPLancaster, York35 min
Sep 1, 3:34 PM EDTAreal Flood WarningCTPCambria, Clearfield, Somerset6 hr
Sep 1, 4:21 PM EDTSevere Thunderstorm WarningCTPLancaster39 min
Sep 1, 4:24 PM EDTFlash Flood Warning EmergencyCatastrophic damage threatCTPAdams, York4 hr
Sep 1, 4:40 PM EDTAreal Flood WarningCTPBedford, Blair, Cambria, Centre, Clearfield, Franklin and 4 more6 hr
Sep 1, 5:41 PM EDTAreal Flood WarningCTPAdams, Centre, Columbia, Cumberland, Dauphin, Franklin and 15 more14 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.