Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 699

July 29, 201117 counties in New Jersey; 22 counties in New York; 45 counties in Pennsylvania

The Storm Prediction Center issued this severe thunderstorm watch at Jul 29, 2011, 2:40 PM EDT for 17 counties in New Jersey; 22 counties in New York; 45 counties in Pennsylvania. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued: Jul 29, 2011, 2:40 PM EDT (18:40 UTC)
Expired: Jul 29, 2011, 11:00 PM EDT
In force: 8 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 84 counties

Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Broome County, NY, Chemung County, NY, Chenango County, NY, Columbia County, NY, Cortland County, NY, Delaware County, NY, Dutchess County, NY, Greene County, NY, Kings County, NY, New York County, NY, Orange County, NY, Otsego County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Tioga County, NY, Tompkins County, NY, Ulster County, NY, Westchester County, NY, Adams County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Bradford County, PA, Bucks County, PA, Cambria County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA, York County, PA

The radar

The State College radar (KCCX), 123 km from the middle of the area, began a volume at 18:42 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

37 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jul 29, 2:40 PM EDT	Severe Thunderstorm Warning	BGM	Bradford, Susquehanna	50 min
Jul 29, 3:15 PM EDT	Severe Thunderstorm Warning	BGM	Susquehanna	60 min
Jul 29, 3:39 PM EDT	Severe Thunderstorm Warning	CTP	Columbia, Montour, Schuylkill	66 min
Jul 29, 3:59 PM EDT	Tornado Warning	BGM	Lackawanna, Susquehanna, Wayne	46 min
Jul 29, 4:04 PM EDT	Severe Thunderstorm Warning	CTP	Blair, Cambria, Huntingdon, Mifflin	56 min
Jul 29, 4:09 PM EDT	Severe Thunderstorm Warning	BGM	Luzerne	38 min
Jul 29, 4:25 PM EDT	Severe Thunderstorm Warning	BGM	Delaware, Otsego	65 min
Jul 29, 4:26 PM EDT	Severe Thunderstorm Warning	BGM	Sullivan	23 min
Jul 29, 4:29 PM EDT	Tornado Warning	BGM	Sullivan	31 min
Jul 29, 4:30 PM EDT	Severe Thunderstorm Warning	CTP	Columbia, Northumberland, Schuylkill	60 min
Jul 29, 4:32 PM EDT	Severe Thunderstorm Warning	OKX	Orange	43 min
Jul 29, 4:36 PM EDT	Tornado Warning	BGM	Pike, Wayne	39 min
Jul 29, 4:40 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	65 min
Jul 29, 4:54 PM EDT	Tornado Warning	OKX	Orange	36 min
Jul 29, 4:59 PM EDT	Severe Thunderstorm Warning	BGM	Lackawanna, Wayne	61 min
Jul 29, 5:11 PM EDT	Tornado Warning	BGM	Pike	49 min
Jul 29, 5:22 PM EDT	Tornado Warning	OKX	Orange, Rockland, Westchester	38 min
Jul 29, 5:34 PM EDT	Severe Thunderstorm Warning	OKX	Orange	41 min
Jul 29, 5:39 PM EDT	Severe Thunderstorm Warning	BGM	Pike, Wayne	36 min
Jul 29, 5:57 PM EDT	Tornado Warning	OKX	Rockland, Westchester	33 min
Jul 29, 5:59 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	61 min
Jul 29, 6:05 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	55 min
Jul 29, 6:16 PM EDT	Severe Thunderstorm Warning	OKX	Passaic	44 min
Jul 29, 6:24 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	66 min
Jul 29, 6:25 PM EDT	Severe Thunderstorm Warning	PHI	Middlesex	20 min
Jul 29, 6:26 PM EDT	Tornado Warning	OKX	Westchester	34 min
Jul 29, 6:39 PM EDT	Severe Thunderstorm Warning	CTP	Somerset	30 min
Jul 29, 6:43 PM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	49 min
Jul 29, 6:49 PM EDT	Severe Thunderstorm Warning	OKX	Orange, Rockland, Westchester	27 min
Jul 29, 6:56 PM EDT	Severe Thunderstorm Warning	OKX	Bergen, Passaic	34 min
Jul 29, 7:03 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	46 min
Jul 29, 7:13 PM EDT	Severe Thunderstorm Warning	OKX	Hudson	32 min
Jul 29, 7:14 PM EDT	Severe Thunderstorm Warning	PHI	Burlington	42 min
Jul 29, 7:27 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Monmouth, Ocean	63 min
Jul 29, 8:27 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Ocean	18 min
Jul 29, 8:34 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Ocean	44 min
Jul 29, 9:13 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Ocean	62 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.7 hours before the alert went out and 255 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: 529 J/kg
Mixed-layer CIN: -105 J/kg
Mixed-layer LCL: 1236 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 78 m²/s²
0-3 km storm-relative helicity: 128 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 29, 12:57 PM EDT	Mesoscale Discussion	SPC	Bergen, Essex, Hudson, Hunterdon, Morris, Passaic and 4 more	2 hr
Jul 29, 4:40 PM EDT	Mesoscale Discussion	SPC	Bergen, Burlington, Camden, Essex, Hudson, Hunterdon and 10 more	95 min
Jul 29, 5:03 PM EDT	Tornado Watch	SPC	Bergen, Passaic, Sussex	3 hr
Jul 29, 6:17 PM EDT	Mesoscale Discussion	SPC	Salem	88 min
Jul 29, 3:31 AM EDT	Mesoscale Discussion	SPC	Allegany, Cattaraugus, Chautauqua, Erie, Wyoming	89 min
Jul 29, 3:56 AM EDT	Severe Thunderstorm Watch	SPC	Allegany, Cattaraugus, Chautauqua, Erie, Genesee, Livingston and 1 more	5 hr
Jul 29, 2:06 PM EDT	Mesoscale Discussion	SPC	Allegheny, Armstrong, Beaver, Bedford, Blair, Butler and 9 more	84 min

Nearby

Severe Thunderstorm Watches in Pennsylvania, 2011 Severe Thunderstorm Watches in New York, 2011 Severe Thunderstorm Watches in New Jersey, 2011 Every severe thunderstorm 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.