Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 388
The Storm Prediction Center issued this severe thunderstorm watch at May 27, 2011, 12:57 PM EDT for 5 states. It was in force for 9 hr.
The area
The outline as issued.
The facts
- Issued
- May 27, 2011, 12:57 PM EDT (16:57 UTC)
- Expired
- May 27, 2011, 10:00 PM EDT
- In force
- 9 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 104 counties
Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Washington County, MD, Broome County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Delaware County, NY, Madison County, NY, Oneida County, NY, Otsego County, NY, Sullivan County, NY, Tioga County, NY, Tompkins County, NY, Adams County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Bradford County, PA, Carbon County, PA, Centre County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin 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, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA, York County, PA, Albemarle County, VA, Arlington County, VA, Augusta 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 Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Pendleton County, WV
The radar
The Sterling radar (KLWX), 104 km from the middle of the area, began a volume at 16:57 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
- 70%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
53 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 27, 3:13 PM EDT | Severe Thunderstorm Warning | LWX | Allegany | 38 min |
| May 27, 3:19 PM EDT | Severe Thunderstorm Warning | CTP | Bedford, Somerset | 67 min |
| May 27, 3:51 PM EDT | Severe Thunderstorm Warning | CTP | Bedford, Blair, Cambria, Huntingdon, Somerset | 54 min |
| May 27, 4:14 PM EDT | Severe Thunderstorm Warning | CTP | Clinton, Potter | 46 min |
| May 27, 4:46 PM EDT | Severe Thunderstorm Warning | CTP | Bedford, Blair, Huntingdon, Mifflin | 59 min |
| May 27, 4:57 PM EDT | Flash Flood Warning | LWX | Allegany | 6 hr |
| May 27, 5:01 PM EDT | Severe Thunderstorm Warning | CTP | Clinton, Lycoming, Potter, Tioga | 44 min |
| May 27, 5:04 PM EDT | Severe Thunderstorm Warning | LWX | Allegany | 15 min |
| May 27, 5:07 PM EDT | Flash Flood Warning | CTP | Bedford, Blair, Cambria, Huntingdon, Somerset | 3 hr |
| May 27, 5:26 PM EDT | Severe Thunderstorm Warning | CTP | Centre, Clinton, Lycoming, Mifflin, Snyder, Union | 49 min |
| May 27, 5:27 PM EDT | Severe Thunderstorm Warning | CTP | Bedford, Fulton, Huntingdon | 63 min |
| May 27, 5:29 PM EDT | Severe Thunderstorm Warning | LWX | Allegany | 31 min |
| May 27, 5:33 PM EDT | Severe Thunderstorm Warning | LWX | Allegany | 27 min |
| May 27, 5:36 PM EDT | Severe Thunderstorm Warning | CTP | Bedford | 69 min |
| May 27, 5:38 PM EDT | Flash Flood Warning | LWX | Allegany | 3 hr |
| May 27, 5:44 PM EDT | Tornado Warning | CTP | Bedford | 46 min |
| May 27, 5:46 PM EDT | Tornado Warning | CTP | Bedford, Fulton, Huntingdon | 59 min |
| May 27, 5:47 PM EDT | Severe Thunderstorm Warning | CTP | Centre, Huntingdon, Juniata, Mifflin | 58 min |
| May 27, 5:56 PM EDT | Severe Thunderstorm Warning | BGM | Broome, Chenango, Tioga | 64 min |
| May 27, 5:56 PM EDT | Severe Thunderstorm Warning | CTP | Tioga | 64 min |
| May 27, 5:57 PM EDT | Flash Flood Warning | LWX | Rockingham, Shenandoah | 2 hr |
| May 27, 5:59 PM EDT | Severe Thunderstorm Warning | CTP | Columbia, Sullivan | 61 min |
| May 27, 6:01 PM EDT | Tornado Warning | CTP | Tioga | 59 min |
| May 27, 6:15 PM EDT | Tornado Warning | CTP | Bedford, Fulton | 45 min |
| May 27, 6:16 PM EDT | Severe Thunderstorm Warning | CTP | Centre, Clinton, Lycoming, Mifflin, Snyder, Tioga and 1 more | 59 min |
| May 27, 6:34 PM EDT | Severe Thunderstorm Warning | LWX | Culpeper, Fauquier, Prince William, Rappahannock | 41 min |
| May 27, 6:40 PM EDT | Severe Thunderstorm Warning | LWX | Charles | 35 min |
| May 27, 6:40 PM EDT | Severe Thunderstorm Warning | CTP | Bedford, Cumberland, Franklin, Fulton, Huntingdon, Juniata and 2 more | 65 min |
| May 27, 6:45 PM EDT | Tornado Warning | LWX | Fairfax, Prince William, Spotsylvania, Stafford, City of Fredericksburg | 30 min |
| May 27, 6:49 PM EDT | Severe Thunderstorm Warning | CTP | Adams, Cumberland, Dauphin, Franklin, Perry, York | 71 min |
| May 27, 6:52 PM EDT | Severe Thunderstorm Warning | BGM | Broome, Chenango, Cortland | 53 min |
| May 27, 6:55 PM EDT | Severe Thunderstorm Warning | BGM | Broome, Tioga | 65 min |
| May 27, 6:58 PM EDT | Severe Thunderstorm Warning | LWX | Charles, Prince George's | 32 min |
| May 27, 7:00 PM EDT | Severe Thunderstorm Warning | CTP | Tioga | 45 min |
| May 27, 7:06 PM EDT | Severe Thunderstorm Warning | LWX | Fairfax, Fauquier, Loudoun, Prince William, City of Fairfax, City of Manassas and 1 more | 39 min |
| May 27, 7:21 PM EDT | Severe Thunderstorm Warning | LWX | Charles, Montgomery, Prince George's | 39 min |
| May 27, 7:29 PM EDT | Severe Thunderstorm Warning | LWX | Frederick, Montgomery, Washington | 46 min |
| May 27, 7:29 PM EDT | Severe Thunderstorm Warning | BGM | Chemung, Tioga | 61 min |
| May 27, 7:29 PM EDT | Severe Thunderstorm Warning | CTP | Dauphin, Lebanon, York | 46 min |
| May 27, 7:31 PM EDT | Severe Thunderstorm Warning | BGM | Otsego | 29 min |
| May 27, 7:39 PM EDT | Severe Thunderstorm Warning | CTP | Dauphin, Juniata, Mifflin, Northumberland, Perry, Snyder and 1 more | 81 min |
| May 27, 7:52 PM EDT | Severe Thunderstorm Warning | BGM | Chemung, Schuyler, Seneca, Tompkins | 68 min |
| May 27, 7:55 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel, Baltimore, Carroll, Frederick, Howard, Montgomery and 1 more | 50 min |
| May 27, 8:08 PM EDT | Severe Thunderstorm Warning | LWX | Carroll, Frederick, Washington | 22 min |
| May 27, 8:08 PM EDT | Severe Thunderstorm Warning | BGM | Chenango, Cortland, Madison, Oneida | 67 min |
| May 27, 8:28 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Carroll, Howard | 47 min |
| May 27, 8:36 PM EDT | Tornado Warning | CTP | Lycoming, Montour, Sullivan | 39 min |
| May 27, 8:42 PM EDT | Severe Thunderstorm Warning | BGM | Chenango, Madison, Oneida, Otsego | 48 min |
| May 27, 8:47 PM EDT | Severe Thunderstorm Warning | CTP | Adams, York | 58 min |
| May 27, 8:59 PM EDT | Severe Thunderstorm Warning | CTP | Columbia, Dauphin, Lebanon, Northumberland, Schuylkill | 61 min |
| May 27, 9:20 PM EDT | Severe Thunderstorm Warning | CTP | Cumberland, Dauphin, Lebanon, Perry, York | 40 min |
| May 27, 9:43 PM EDT | Severe Thunderstorm Warning | BGM | Chenango, Madison, Oneida, Otsego | 47 min |
| May 27, 9:56 PM EDT | Severe Thunderstorm Warning | BGM | Chenango, Madison, Otsego | 64 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, 5.0 hours before the alert went out and 108 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.
- Mixed-layer CAPE
- 159 J/kg
- Mixed-layer CIN
- -243 J/kg
- Mixed-layer LCL
- 1202 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 102 m²/s²
- 0-3 km storm-relative helicity
- 113 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 27, 12:24 PM EDT | Mesoscale Discussion | SPC | Baltimore, Carroll, Frederick, Howard, Montgomery, Prince George's and 2 more | 96 min |
| May 27, 3:29 PM EDT | Mesoscale Discussion | SPC | Saint Mary's | 91 min |
| May 27, 6:14 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Carroll, Cecil, Charles, Frederick and 7 more | 2 hr |
| May 27, 1:18 PM EDT | Mesoscale Discussion | SPC | Washington | 87 min |
| May 27, 2:00 PM EDT | Severe Thunderstorm Watch | SPC | Albany, Columbia, Essex, Fulton, Greene, Hamilton and 9 more | 6 hr |
| May 27, 5:49 PM EDT | Mesoscale Discussion | SPC | Albany, Columbia, Essex, Fulton, Greene, Hamilton and 8 more | 56 min |
| May 26, 8:54 PM EDT | Mesoscale Discussion | SPC | Adams, Berks, Bradford, Carbon, Columbia, Cumberland and 21 more | 66 min |
| May 26, 11:22 PM EDT | Mesoscale Discussion | SPC | Albemarle, Amherst, Appomattox, Augusta, Bedford, Buckingham and 18 more | 113 min |
| May 27, 11:26 AM EDT | Mesoscale Discussion | SPC | Brunswick, Dinwiddie, Greensville, Lunenburg, Mecklenburg, Nottoway and 1 more | 94 min |
| May 27, 12:06 PM EDT | Severe Thunderstorm Watch | SPC | Amelia, Amherst, Appomattox, Bedford, Botetourt, Brunswick and 52 more | 7 hr |
| May 27, 6:24 PM EDT | Mesoscale Discussion | SPC | Albemarle, Amelia, Amherst, Appomattox, Bedford, Brunswick and 43 more | 66 min |
Nearby
Severe Thunderstorm Watches in Pennsylvania, 2011Severe Thunderstorm Watches in Virginia, 2011Severe Thunderstorm Watches in Maryland, 2011Every 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.