Alert archive / Pennsylvania / Flash Flood Watches in 2011

Flash Flood Watch 11, NWS State College, PA

September 4, 201118 counties in Pennsylvania

NWS State College, PA issued this flash flood watch at Sep 4, 2011, 11:29 PM EDT for 18 counties in Pennsylvania. It was in force for 21 hr.

The area

The counties it named.

The facts

Issued: Sep 4, 2011, 11:29 PM EDT (03:29 UTC)
Expired: Sep 5, 2011, 8:00 PM EDT
In force: 21 hr
Issued by: NWS State College, PA
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, Lycoming County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Tioga County, PA, Union County, PA, York County, PA

The radar

The State College radar (KCCX), 99 km from the middle of the area, began a volume at 03:33 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 00:00Z, 3.5 hours before the alert went out and 193 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: 2382 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 895 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 63 m²/s²
0-3 km storm-relative helicity: 64 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.2

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS State College, PA wrote its last area forecast discussion before this flash flood watch went out at Sep 4, 10:56 PM EDT, 33 minutes earlier.

Area forecast discussion, Sep 4, 10:56 PM EDT, 33 minutes before

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Hazardous weather outlook, Sep 4, 10:44 PM EDT, 45 minutes before

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In the hours before

Special weather statement, Sep 4, 8:21 PM EDT, 3 hours 8 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
821 PM EDT SUN SEP 4 2011

PAZ028-036-050-052-056>058-063>065-050115-
ADAMS PA-CUMBERLAND PA-DAUPHIN PA-FRANKLIN PA-JUNIATA PA-
NORTHUMBERLAND PA-PERRY PA-SCHUYLKILL PA-SNYDER PA-YORK PA-
821 PM EDT SUN SEP 4 2011

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT ADAMS...CUMBERLAND...
DAUPHIN...FRANKLIN...NORTHEASTERN JUNIATA...NORTHWESTERN YORK...
PERRY...SOUTHEASTERN SNYDER...SOUTHERN NORTHUMBERLAND AND WEST
CENTRAL SCHUYLKILL COUNTIES...

AT 819 PM EDT...A LINE OF STRONG THUNDERSTORMS WAS LOCATED FROM
RICHFIELD TO CLEAR SPRING...MOVING EAST AT 25 MPH.

WIND GUSTS TO 50 MPH AND SMALL HAIL ARE POSSIBLE WITH THESE STORMS.
VERY HEAVY RAIN WILL FALL FROM THESE STORMS...AND WILL CAUSE WATER TO
POND ON ROADS AND FILL POOR DRAINAGE AREAS. THE RAIN WILL CAUSE RAPID
RISES ON SMALL STREAMS AND CREEKS. THESE STORMS WILL AFFECT
MILLERSTOWN...MEISERVILLE...PORT TREVERTON...HERNDON...URBAN AND
CARROLL VALLEY.

THIS WILL IMPACT THE FOLLOWING CENTRAL PENNSYLVANIA INTERSTATES...THE
PENNSYLVANIA TURNPIKE BETWEEN MILE MARKERS 196 AND 244...I-81 BETWEEN
MILE MARKERS 1 AND 77...I-83 BETWEEN MILE MARKERS 37 AND 50...I-283.

THIS WILL ALSO IMPACT THE FOLLOWING MAJOR ROADS...THE HARRISBURG
EXPRESSWAY...ROUTE 11...ROUTE 11/15...ROUTE 15...ROUTE 22...ROUTE
30...ROUTE 209...ROUTE 322/22...STATE ROAD 94...STATE ROAD 97.

LAT...LON 4017 7771 4069 7720 4076 7640 4053 7658
      4048 7668 4042 7666 3971 7719 3972 7799

FORECASTER: MARTIN

Local storm report, Sep 4, 8:51 PM EDT, 2 hours 38 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
851 PM EDT SUN SEP 04 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 PM     HAIL             MILTON                  41.01N  76.85W
09/04/2011  E1.00 INCH       NORTHUMBERLAND     PA   PUBLIC

&&

EVENT NUMBER CTP1100395

KF

Special weather statement, Sep 4, 9:11 PM EDT, 2 hours 18 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
911 PM EDT SUN SEP 4 2011

PAZ028-036-050>053-056>059-063>066-050215-
ADAMS PA-COLUMBIA PA-CUMBERLAND PA-DAUPHIN PA-FRANKLIN PA-JUNIATA PA-
LANCASTER PA-LEBANON PA-MONTOUR PA-NORTHUMBERLAND PA-PERRY PA-
SCHUYLKILL PA-SNYDER PA-YORK PA-
911 PM EDT SUN SEP 4 2011

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT ADAMS...CUMBERLAND...
DAUPHIN...EASTERN FRANKLIN...EASTERN PERRY...LEBANON...NORTHEASTERN
JUNIATA...NORTHWESTERN LANCASTER...SCHUYLKILL...SOUTHEASTERN
MONTOUR...SOUTHEASTERN SNYDER...SOUTHERN COLUMBIA...SOUTHERN
NORTHUMBERLAND AND WESTERN YORK COUNTIES...

AT 906 PM EDT...A LINE OF STRONG THUNDERSTORMS WAS LOCATED FROM
FERNDALE TO HALIFAX TO SHERMANSDALE TO 9 MILES SOUTHWEST OF
HAGERSTOWN...MOVING EAST AT 30 MPH.

WIND GUSTS TO 50 MPH AND SMALL HAIL ARE POSSIBLE WITH THESE STORMS.
VERY HEAVY RAIN WILL FALL FROM THESE STORMS...AND WILL CAUSE WATER TO
POND ON ROADS AND FILL POOR DRAINAGE AREAS. THE RAIN WILL CAUSE RAPID
RISES ON SMALL STREAMS AND CREEKS. THESE STORMS WILL AFFECT
CATAWISSA...BLOOMSBURG...KULPMONT...AND ROUGH AND READY...MOUNT
CARMEL...CENTRALIA...NUMIDIA...AND MAINVILLE...RINGTOWN AND SHUMANS.

THIS WILL IMPACT THE FOLLOWING CENTRAL PENNSYLVANIA INTERSTATES...THE
PENNSYLVANIA TURNPIKE BETWEEN MILE MARKERS 207 AND 266...I-78 BETWEEN
MILE MARKERS 0 AND 8...I-80 BETWEEN MILE MARKERS 236 AND 247...I-81
BETWEEN MILE MARKERS 1 AND 139...I-83 BETWEEN MILE MARKERS 18 AND
50...I-283.

LAT...LON 4039 7737 4071 7697 4107 7637 4101 7622
      4095 7620 4091 7599 4079 7583 4056 7608
      4049 7642 4039 7627 3971 7689 3972 7787

FORECASTER: MARTIN

Special weather statement, Sep 4, 10:11 PM EDT, 1 hour 18 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1011 PM EDT SUN SEP 4 2011

PAZ051>053-057>059-065-066-050315-
COLUMBIA PA-DAUPHIN PA-LANCASTER PA-LEBANON PA-MONTOUR PA-
NORTHUMBERLAND PA-SCHUYLKILL PA-YORK PA-
1011 PM EDT SUN SEP 4 2011

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT COLUMBIA...EAST CENTRAL
NORTHUMBERLAND...LEBANON...NORTH CENTRAL YORK...NORTHERN LANCASTER...
SCHUYLKILL...SOUTHEASTERN DAUPHIN AND SOUTHEASTERN MONTOUR
COUNTIES...

AT 1007 PM EDT...A LINE OF STRONG THUNDERSTORMS WAS LOCATED FROM
SCOTCH VALLEY TO PINE GROVE TO LAWN...MOVING EAST AT 25 MPH.

WIND GUSTS TO 50 MPH AND SMALL HAIL ARE POSSIBLE WITH THESE STORMS.
VERY HEAVY RAIN WILL FALL FROM THESE STORMS...AND WILL CAUSE WATER TO
POND ON ROADS AND FILL POOR DRAINAGE AREAS. THE RAIN WILL CAUSE RAPID
RISES ON SMALL STREAMS AND CREEKS. THESE STORMS WILL AFFECT SUMMIT
STATION...ST. CLAIR...SHEPPTON...AND SHENANDOAH...SCHUYLKILL HAVEN...
PORT CARBON...NEW PHILADELPHIA...AND MIDDLEPORT...TUSCARORA AND
ORWIGSBURG.

THIS WILL IMPACT THE FOLLOWING CENTRAL PENNSYLVANIA INTERSTATES...THE
PENNSYLVANIA TURNPIKE BETWEEN MILE MARKERS 240 AND 295...I-78 BETWEEN
MILE MARKERS 0 AND 8...I-80 BETWEEN MILE MARKERS 227 AND 247...I-81
BETWEEN MILE MARKERS 66 AND 139...I-83 BETWEEN MILE MARKERS 34 AND
50...I-283.

LAT...LON 4068 7588 4063 7599 4057 7601 4049 7643
      4020 7596 4017 7592 4011 7593 4010 7594
      4011 7670 4020 7693 4022 7686 4028 7692
      4068 7668 4121 7653 4110 7622 4096 7621
      4091 7605 4091 7599 4081 7587

FORECASTER: MARTIN

Special weather statement, Sep 4, 10:14 PM EDT, 1 hour 15 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1014 PM EDT SUN SEP 4 2011

PAZ036-063>066-050315-
ADAMS PA-CUMBERLAND PA-FRANKLIN PA-LANCASTER PA-YORK PA-
1014 PM EDT SUN SEP 4 2011

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT ADAMS...CUMBERLAND...
NORTHWESTERN YORK...SOUTHEASTERN FRANKLIN AND WEST CENTRAL LANCASTER
COUNTIES...

AT 1012 PM EDT...A LINE OF STRONG THUNDERSTORMS WAS LOCATED FROM
MERCERSBURG TO CLEAR SPRING...MOVING EAST AT 25 MPH.

WIND GUSTS TO 50 MPH AND SMALL HAIL ARE POSSIBLE WITH THESE STORMS.
VERY HEAVY RAIN WILL FALL FROM THESE STORMS...AND WILL CAUSE WATER TO
POND ON ROADS AND FILL POOR DRAINAGE AREAS. THE RAIN WILL CAUSE RAPID
RISES ON SMALL STREAMS AND CREEKS. THESE STORMS WILL AFFECT
MERCERSBURG...ST. THOMAS...CHAMBERSBURG...FAYETTEVILLE...SHIPPENSBURG
AND CARROLL VALLEY.

THIS WILL IMPACT THE FOLLOWING CENTRAL PENNSYLVANIA INTERSTATES...THE
PENNSYLVANIA TURNPIKE BETWEEN MILE MARKERS 227 AND 245...I-81 BETWEEN
MILE MARKERS 1 AND 54...I-83 BETWEEN MILE MARKERS 17 AND 40.

LAT...LON 4005 7772 4026 7704 4020 7679 4017 7675
      4012 7673 4016 7667 4010 7645 3971 7700
      3972 7800

FORECASTER: MARTIN

Local storm report, Sep 4, 10:25 PM EDT, 1 hour 4 minutes before

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1025 PM EDT SUN SEP 04 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 PM     HAIL             MILTON                  41.01N  76.85W
09/04/2011  E1.00 INCH       NORTHUMBERLAND     PA   PUBLIC

0920 PM     TSTM WND DMG     GREENCASTLE             39.79N  77.73W
09/04/2011                   FRANKLIN           PA   911 CALL CENTER

            TREES DOWN

&&

EVENT NUMBER CTP1100395 CTP1100396

MACH

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 4, 8:11 PM EDT	Areal Flood Advisory	CTP	Columbia, Montour, Northumberland, Snyder, Union	3 hr
Sep 4, 8:21 PM EDT	Special Weather Statement	CTP	Adams, Cumberland, Dauphin, Franklin, Perry	54 min
Sep 4, 9:11 PM EDT	Special Weather Statement	CTP	Adams, Columbia, Cumberland, Dauphin, Lebanon, Northumberland and 3 more	64 min
Sep 4, 9:51 PM EDT	Areal Flood Advisory	CTP	Cumberland, Dauphin, Lebanon, Northumberland, Perry, Schuylkill and 1 more	3 hr
Sep 4, 10:11 PM EDT	Special Weather Statement	CTP	Columbia, Dauphin, Lebanon, Schuylkill	64 min
Sep 4, 10:14 PM EDT	Special Weather Statement	CTP	Adams, Cumberland, Franklin, York	61 min
Sep 4, 10:31 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster, Lebanon, Schuylkill	44 min
Sep 4, 10:54 PM EDT	Areal Flood Advisory	CTP	Adams, Cumberland, Franklin, Juniata, Perry, Snyder and 1 more	3 hr
Sep 4, 11:35 PM EDT	Special Weather Statement	CTP	Adams, Dauphin, Lebanon, York	70 min
Sep 4, 11:44 PM EDT	Flash Flood Warning	CTP	Adams, Cumberland, Dauphin, Lancaster, Lebanon, Perry and 1 more	3 hr
Sep 5, 12:38 AM EDT	Special Weather Statement	CTP	York	67 min
Sep 5, 12:45 AM EDT	Areal Flood Advisory	CTP	Columbia, Dauphin, Montour, Northumberland, Schuylkill	4 hr
Sep 5, 1:41 AM EDT	Flash Flood Warning	CTP	Columbia, Dauphin, Lebanon, Lycoming, Montour, Northumberland and 2 more	4 hr
Sep 5, 6:16 PM EDT	Special Weather Statement	CTP	Lancaster	29 min

Nearby

Flash Flood Watches in Pennsylvania, 2011 Every flash flood watch in 2011

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.