Alert archive / Pennsylvania / Flash Flood Watches in 2021

Flash Flood Watch 3, NWS State College, PA

July 12, 202118 counties in Pennsylvania

NWS State College, PA issued this flash flood watch at Jul 12, 2021, 1:21 PM EDT for 18 counties in Pennsylvania. It took effect at Jul 12, 2021, 1:36 PM EDT. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued
Jul 12, 2021, 1:21 PM EDT (17:21 UTC)
In effect from
Jul 12, 2021, 1:36 PM EDT
Expired
Jul 13, 2021, 2:00 AM EDT
In force
12 hr
Issued by
NWS State College, PA
Flood severity
None

Counties Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Juniata County, PA, Lebanon County, PA, Lycoming County, PA, McKean County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Tioga County, PA, Union County, PA, Warren County, PA, York County, PA

The radar

The State College radar (KCCX), 72 km from the middle of the area, began a volume at 17:22 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, 5.4 hours before the alert went out and 223 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 2021-07-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 974 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 2021-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 10 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
974 J/kg
Mixed-layer CIN
-83 J/kg
Mixed-layer LCL
724 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
10 m²/s²
0-3 km storm-relative helicity
53 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.8

Open this sounding in Storm Lab

The text

As transmitted.

267 
WGUS61 KCTP 121721
FFACTP

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service State College PA
121 PM EDT Mon Jul 12 2021

.Slow moving thunderstorms will impact the region this afternoon and 
tonight. Locations in the watch have received multiple rounds of 
heavy rain over the past several days and are prone to flash 
flooding from new rainfall amounts of just 1.50 inches or less 
during a 3 hour period.

PAZ028-037-041-042-046-049>053-056>059-063-065-130600-
/O.NEW.KCTP.FF.A.0003.210712T1900Z-210713T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Juniata-Tioga-Northern Lycoming-Sullivan-Southern Lycoming-Union-
Snyder-Montour-Northumberland-Columbia-Perry-Dauphin-Schuylkill-
Lebanon-Cumberland-York-
Including the cities of Newport, Trout Run, Selinsgrove, Wellsboro, 
Shamokin, Laporte, Lebanon, Sunbury, Hershey, Mifflintown, 
Harrisburg, Pottsville, Williamsport, Mansfield, York, Danville, 
Bloomsburg, Berwick, Lewisburg, and Carlisle
121 PM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...

The National Weather Service in State College has issued a

* Flash Flood Watch for a portion of central Pennsylvania, including 
  the following areas, Columbia, Cumberland, Dauphin, Juniata, 
  Lebanon, Montour, Northern Lycoming, Northumberland, Perry, 
  Schuylkill, Snyder, Southern Lycoming, Sullivan, Tioga, Union and 
  York.

* Through late tonight.

* Excessive rain from multiple thunderstorms. Rainfall could total 2 
  to 3 inches in some locations.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Lambert/Travis
2 follow-up statements
469 
WGUS61 KCTP 121736
FFACTP

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service State College PA
136 PM EDT Mon Jul 12 2021

.Slow moving thunderstorms will impact the region this afternoon and 
tonight. Locations in the watch have received multiple rounds of 
heavy rain over the past several days and are prone to flash 
flooding from new rainfall amounts of just 1.25 and 1.50 inches over 
a 1 and 3 hour period respectively.
during a 3 hour period.

PAZ004>006-130300-
/O.EXB.KCTP.FF.A.0003.210712T1736Z-210713T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Warren-McKean-Potter-
Including the cities of Bradford, Coudersport, and Warren
136 PM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH IN EFFECT UNTIL 11 PM EDT THIS EVENING...

The National Weather Service in State College has expanded the

* Flash Flood Watch to include a portion of central Pennsylvania, 
  including the following areas, McKean, Potter and Warren.

* Until 11 PM EDT this evening.

* Excessive rain from multiple thunderstorms. Rainfall could total 2 
  to 3 inches in some locations.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

PAZ028-037-041-042-046-049>053-056>059-063-065-130315-
/O.CON.KCTP.FF.A.0003.210712T1900Z-210713T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Juniata-Tioga-Northern Lycoming-Sullivan-Southern Lycoming-Union-
Snyder-Montour-Northumberland-Columbia-Perry-Dauphin-Schuylkill-
Lebanon-Cumberland-York-
Including the cities of Newport, Trout Run, Selinsgrove, Wellsboro, 
Shamokin, Laporte, Lebanon, Sunbury, Hershey, Mifflintown, 
Harrisburg, Pottsville, Williamsport, Mansfield, York, Danville, 
Bloomsburg, Berwick, Lewisburg, and Carlisle
136 PM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH LATE TONIGHT...

The Flash Flood Watch continues for

* A portion of central Pennsylvania, including the following areas, 
  Columbia, Cumberland, Dauphin, Juniata, Lebanon, Montour, Northern 
  Lycoming, Northumberland, Perry, Schuylkill, Snyder, Southern 
  Lycoming, Sullivan, Tioga, Union and York.

* Through late tonight.

* Excessive rain from multiple thunderstorms. Rainfall could total 2 
  to 3 inches in some locations.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Lambert/Devoir
019 
WGUS61 KCTP 130311
FFACTP

Flood Watch
National Weather Service State College PA
1111 PM EDT Mon Jul 12 2021

PAZ004>006-130415-
/O.EXP.KCTP.FF.A.0003.000000T0000Z-210713T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Warren-McKean-Potter-
Including the cities of Bradford, Coudersport, and Warren
1111 PM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH HAS EXPIRED...

The Flash Flood Watch for a portion of central Pennsylvania, 
including the following areas, McKean, Potter and Warren has expired.

Flooding is no longer expected to pose a threat.

$$

PAZ028-037-041-042-046-049>053-056>059-063-065-130600-
/O.CON.KCTP.FF.A.0003.000000T0000Z-210713T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Juniata-Tioga-Northern Lycoming-Sullivan-Southern Lycoming-Union-
Snyder-Montour-Northumberland-Columbia-Perry-Dauphin-Schuylkill-
Lebanon-Cumberland-York-
Including the cities of Newport, Trout Run, Selinsgrove, Wellsboro, 
Shamokin, Laporte, Lebanon, Sunbury, Hershey, Mifflintown, 
Harrisburg, Pottsville, Williamsport, Mansfield, York, Danville, 
Bloomsburg, Berwick, Lewisburg, and Carlisle
1111 PM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 2 AM EDT TUESDAY...

The Flash Flood Watch continues for

* A portion of central Pennsylvania, including the following areas, 
  Columbia, Cumberland, Dauphin, Juniata, Lebanon, Montour, Northern 
  Lycoming, Northumberland, Perry, Schuylkill, Snyder, Southern 
  Lycoming, Sullivan, Tioga, Union and York.

* Until 2 AM EDT Tuesday.

* Localized downpours remain possible in the Watch area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Evanego

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 11, 8:03 PM EDTSevere Thunderstorm WarningCTPClinton, Columbia, Lycoming, Montour, Northumberland, Snyder and 1 more42 min
Jul 11, 8:43 PM EDTSevere Thunderstorm WarningCTPColumbia, Lycoming, Montour, Northumberland, Sullivan62 min
Jul 11, 8:44 PM EDTSevere Thunderstorm WarningCTPCumberland, Dauphin, Lebanon, Perry, Schuylkill76 min
Jul 11, 8:52 PM EDTTornado WarningCTPDauphin23 min
Jul 11, 9:07 PM EDTAreal Flood AdvisoryCTPColumbia, Lycoming, Montour, Northumberland, Sullivan, Union2 hr
Jul 11, 9:08 PM EDTSpecial Weather StatementCTPFranklin37 min
Jul 11, 9:32 PM EDTSpecial Weather StatementCTPFulton28 min
Jul 11, 9:32 PM EDTSevere Thunderstorm WarningCTPCumberland, Dauphin, Lebanon, York58 min
Jul 11, 9:52 PM EDTSevere Thunderstorm WarningCTPSchuylkill53 min
Jul 11, 10:06 PM EDTFlash Flood WarningCTPCumberland, Dauphin, Lebanon, York118 min
Jul 11, 10:35 PM EDTSpecial Weather StatementCTPLebanon, York70 min
Jul 12, 12:04 AM EDTAreal Flood AdvisoryCTPCumberland, Dauphin, Lebanon, York116 min
Jul 12, 2:15 PM EDTSpecial Weather StatementCTPLancaster60 min
Jul 12, 2:34 PM EDTSpecial Weather StatementCTPMifflin26 min
Jul 12, 2:36 PM EDTSpecial Weather StatementCTPPerry24 min
Jul 12, 2:45 PM EDTSpecial Weather StatementCTPAdams, Franklin60 min
Jul 12, 2:49 PM EDTSevere Thunderstorm WarningCTPCumberland, Perry41 min
Jul 12, 2:59 PM EDTSpecial Weather StatementCTPMifflin31 min
Jul 12, 3:17 PM EDTSpecial Weather StatementCTPLebanon43 min
Jul 12, 3:30 PM EDTSpecial Weather StatementCTPJuniata45 min
Jul 12, 3:31 PM EDTAreal Flood AdvisoryCTPLancaster119 min
Jul 12, 3:55 PM EDTSevere Thunderstorm WarningCTPDauphin, Perry35 min
Jul 12, 3:56 PM EDTFlash Flood WarningCTPLancaster2 hr
Jul 12, 3:57 PM EDTSevere Thunderstorm WarningCTPLancaster63 min
Jul 12, 3:59 PM EDTSevere Thunderstorm WarningCTPCumberland, York46 min
Jul 12, 4:11 PM EDTSevere Thunderstorm WarningCTPCumberland, Dauphin, Lancaster, Lebanon, York34 min
Jul 12, 4:42 PM EDTSevere Thunderstorm WarningCTPDauphin, Lancaster, Lebanon, York63 min
Jul 12, 4:57 PM EDTAreal Flood AdvisoryCTPLancaster2 hr
Jul 12, 5:29 PM EDTSevere Thunderstorm WarningCTPLancaster61 min
Jul 12, 5:42 PM EDTAreal Flood AdvisoryCTPLancaster93 min
Jul 12, 6:31 PM EDTAreal Flood AdvisoryCTPLancaster119 min
Jul 12, 6:43 PM EDTAreal Flood AdvisoryCTPTioga92 min

Nearby

Flash Flood Watches in Pennsylvania, 2021Every flash flood watch 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.