Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 479
The Storm Prediction Center issued this severe thunderstorm watch at Jul 7, 2012, 6:14 PM EDT for 4 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 7, 2012, 6:14 PM EDT (22:14 UTC)
- Expired
- Jul 7, 2012, 9:37 PM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 59 counties
New Castle County, DE, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Kent County, MD, Washington County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Salem County, NJ, Somerset County, NJ, Warren County, NJ, Adams County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Bucks County, PA, Cambria County, PA, Cameron 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, Elk County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Mifflin County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Union County, PA, York County, PA
The radar
The Sterling radar (KLWX), 132 km from the middle of the area, began a volume at 22:17 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
- 5%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 20%
- 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
- 90%
Warnings issued inside it
12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 7, 6:21 PM EDT | Severe Thunderstorm Warning | CTP | Dauphin, Juniata, Perry | 39 min |
| Jul 7, 6:21 PM EDT | Severe Thunderstorm Warning | CTP | Cumberland, Franklin, Huntingdon, Juniata, Perry | 39 min |
| Jul 7, 6:21 PM EDT | Severe Thunderstorm Warning | CTP | Lancaster, Lebanon | 72 min |
| Jul 7, 6:25 PM EDT | Severe Thunderstorm Warning | PHI | Hunterdon, Somerset, Warren | 37 min |
| Jul 7, 6:54 PM EDT | Severe Thunderstorm Warning | PHI | Mercer, Middlesex, Monmouth, Ocean, Somerset | 46 min |
| Jul 7, 6:58 PM EDT | Severe Thunderstorm Warning | PHI | New Castle | 48 min |
| Jul 7, 6:59 PM EDT | Severe Thunderstorm Warning | CTP | Cumberland, Franklin, Juniata, Perry, York | 61 min |
| Jul 7, 7:22 PM EDT | Severe Thunderstorm Warning | PHI | Monmouth, Ocean | 53 min |
| Jul 7, 7:42 PM EDT | Severe Thunderstorm Warning | PHI | Burlington, Ocean | 63 min |
| Jul 7, 7:51 PM EDT | Severe Thunderstorm Warning | CTP | Cumberland, Dauphin, Lancaster, Lebanon, Perry, York | 69 min |
| Jul 7, 8:59 PM EDT | Severe Thunderstorm Warning | CTP | Lancaster | 16 min |
| Jul 7, 9:05 PM EDT | Severe Thunderstorm Warning | PHI | Chester, Delaware | 32 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, 10.2 hours before the alert went out and 132 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
- 1804 J/kg
- Mixed-layer CIN
- -87 J/kg
- Mixed-layer LCL
- 1395 m above ground
- 0-6 km bulk shear
- 10 kt
- 0-1 km storm-relative helicity
- 40 m²/s²
- 0-3 km storm-relative helicity
- 90 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 7, 5:43 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle | 62 min |
| Jul 7, 11:19 AM EDT | Mesoscale Discussion | SPC | Bergen, Essex, Hudson, Hunterdon, Mercer, Middlesex and 7 more | 86 min |
| Jul 7, 11:41 AM EDT | Severe Thunderstorm Watch | SPC | Bergen, Essex, Hudson, Hunterdon, Mercer, Middlesex and 6 more | 7 hr |
| Jul 7, 1:36 PM EDT | Mesoscale Discussion | SPC | Bergen, Essex, Hudson, Hunterdon, Middlesex, Morris and 5 more | 84 min |
| Jul 7, 3:57 PM EDT | Mesoscale Discussion | SPC | Bergen, Essex, Hudson, Hunterdon, Middlesex, Morris and 5 more | 2 hr |
| Jul 7, 1:48 PM EDT | Mesoscale Discussion | SPC | Armstrong, Beaver, Butler, Cameron, Centre, Clarion and 13 more | 57 min |
| Jul 7, 2:16 PM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Armstrong, Beaver, Blair, Butler, Cambria and 21 more | 5 hr |
| Jul 7, 6:59 PM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Beaver, Fayette, Greene, Washington, Westmoreland | 3 hr |
Nearby
Severe Thunderstorm Watches in Pennsylvania, 2012Severe Thunderstorm Watches in New Jersey, 2012Severe Thunderstorm Watches in Maryland, 2012Every severe thunderstorm watch in 2012
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.