Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 610

July 8, 20117 states

The Storm Prediction Center issued this severe thunderstorm watch at Jul 8, 2011, 1:51 PM EDT for 7 states. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Jul 8, 2011, 1:51 PM EDT (17:51 UTC)
Expired: Jul 8, 2011, 9:00 PM EDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 55 kt

All 111 counties

Capitol Planning Region, CT, Greater Bridgeport Planning Region, CT, Lower Connecticut River Valley Planning Region, CT, Naugatuck Valley Planning Region, CT, Northeastern Connecticut Planning Region, CT, Northwest Hills Planning Region, CT, Southeastern Connecticut Planning Region, CT, Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Talbot County, MD, Atlantic County, NJ, Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland 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, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Delaware County, NY, Dutchess County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Suffolk County, NY, Sullivan County, NY, Ulster County, NY, Westchester County, NY, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Columbia County, PA, Dauphin County, PA, Delaware County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, Sullivan County, PA, Susquehanna County, PA, Wayne County, PA, Wyoming County, PA, York County, PA, Albemarle County, VA, Arlington County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Greene County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Prince William County, VA, Rappahannock County, VA, Spotsylvania County, VA, Stafford County, VA

The radar

The Philadelphia radar (KDIX), 103 km from the middle of the area, began a volume at 17:54 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: 10%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 8, 2:00 PM EDT	Flash Flood Warning	CTP	Cumberland, Dauphin, Perry, York	3 hr
Jul 8, 2:48 PM EDT	Severe Thunderstorm Warning	PHI	Monroe	57 min
Jul 8, 2:51 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer, Warren	54 min
Jul 8, 2:53 PM EDT	Severe Thunderstorm Warning	OKX	Orange, Putnam, Rockland, Westchester	67 min
Jul 8, 3:00 PM EDT	Severe Thunderstorm Warning	BGM	Susquehanna, Wyoming	45 min
Jul 8, 3:09 PM EDT	Tornado Warning	LWX	Greene, Madison, Page, Rockingham	36 min
Jul 8, 3:14 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer, Middlesex, Somerset	66 min
Jul 8, 3:14 PM EDT	Flash Flood Warning	BGM	Luzerne, Wyoming	91 min
Jul 8, 3:18 PM EDT	Flash Flood Warning	OKX	Orange, Putnam, Rockland, Westchester	4 hr
Jul 8, 3:24 PM EDT	Flash Flood Warning	LWX	Carroll, Frederick, Washington	3 hr
Jul 8, 3:33 PM EDT	Flash Flood Warning	LWX	Baltimore, Carroll, Frederick, Howard, Montgomery	3 hr
Jul 8, 3:37 PM EDT	Flash Flood Warning	BGM	Susquehanna, Wyoming	64 min
Jul 8, 3:39 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Greene, Madison, Orange	51 min
Jul 8, 3:44 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Warren	76 min
Jul 8, 3:45 PM EDT	Flash Flood Warning	PHI	Philadelphia	3 hr
Jul 8, 3:46 PM EDT	Flash Flood Warning	BGM	Lackawanna, Wayne	3 hr
Jul 8, 3:48 PM EDT	Flash Flood Warning	PHI	Camden	3 hr
Jul 8, 3:48 PM EDT	Severe Thunderstorm Warning	OKX	Orange	26 min
Jul 8, 3:49 PM EDT	Flash Flood Warning	LWX	Baltimore, Carroll, Harford, Howard, City of Baltimore	3 hr
Jul 8, 3:50 PM EDT	Severe Thunderstorm Warning	OKX	Naugatuck Valley Planning Region	40 min
Jul 8, 3:51 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Middlesex, Morris, Somerset, Sussex, Warren	69 min
Jul 8, 4:09 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Calvert, Prince George's	51 min
Jul 8, 4:09 PM EDT	Severe Thunderstorm Warning	OKX	Rockland, Westchester	51 min
Jul 8, 4:10 PM EDT	Flash Flood Warning	LWX	Anne Arundel, Howard, Montgomery, Prince George's	3 hr
Jul 8, 4:10 PM EDT	Flash Flood Warning	PHI	Hunterdon, Morris, Somerset, Sussex, Warren	3 hr
Jul 8, 4:18 PM EDT	Flash Flood Warning	PHI	Monroe	2 hr
Jul 8, 4:21 PM EDT	Severe Thunderstorm Warning	OKX	Lower Connecticut River Valley Planning Region	39 min
Jul 8, 4:22 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Orange, Spotsylvania	38 min
Jul 8, 4:32 PM EDT	Flash Flood Warning	LWX	Albemarle, City of Charlottesville	102 min
Jul 8, 4:42 PM EDT	Severe Thunderstorm Warning	PHI	Morris, Sussex, Warren	78 min
Jul 8, 4:50 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Camden	70 min
Jul 8, 4:54 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Fauquier, Orange, Prince William, Spotsylvania, Stafford	35 min
Jul 8, 5:03 PM EDT	Flash Flood Warning	PHI	Sussex	117 min
Jul 8, 5:03 PM EDT	Tornado Warning	PHI	Atlantic, Burlington, Camden	27 min
Jul 8, 5:07 PM EDT	Flash Flood Warning	LWX	Anne Arundel, Prince George's	3 hr
Jul 8, 5:08 PM EDT	Flash Flood Warning	OKX	Bergen, Passaic	3 hr
Jul 8, 5:10 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Calvert, Charles, Prince George's	50 min
Jul 8, 5:12 PM EDT	Flash Flood Warning	OKX	Naugatuck Valley Planning Region	2 hr
Jul 8, 5:15 PM EDT	Severe Thunderstorm Warning	OKX	Bergen, Passaic	26 min
Jul 8, 5:16 PM EDT	Flash Flood Warning	OKX	Lower Connecticut River Valley Planning Region	119 min
Jul 8, 5:27 PM EDT	Severe Thunderstorm Warning	LWX	Charles, Prince George's, Saint Mary's	48 min
Jul 8, 5:44 PM EDT	Flash Flood Warning	PHI	New Castle	3 hr
Jul 8, 5:53 PM EDT	Severe Thunderstorm Warning	PHI	Kent	82 min
Jul 8, 5:53 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Calvert, Charles, Prince George's	26 min
Jul 8, 6:23 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	82 min
Jul 8, 6:34 PM EDT	Flash Flood Warning	LWX	Calvert, Charles, Saint Mary's	76 min
Jul 8, 7:13 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Cape May, Cumberland, Ocean	77 min
Jul 8, 7:49 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	56 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 5.9 hours before the alert went out and 153 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: 1352 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 668 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 88 m²/s²
0-3 km storm-relative helicity: 134 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 2.9

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 8, 11:44 AM EDT	Mesoscale Discussion	SPC		61 min
Jul 8, 5:52 PM EDT	Mesoscale Discussion	SPC		83 min
Jul 8, 1:01 PM EDT	Mesoscale Discussion	SPC	Bedford, Floyd, Franklin, Greensville, Halifax, Henry and 12 more	89 min

Nearby

Severe Thunderstorm Watches in Pennsylvania, 2011 Severe Thunderstorm Watches in Virginia, 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.