Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 270
The Storm Prediction Center issued this severe thunderstorm watch at Jun 14, 2021, 2:06 PM EDT for 13 counties in New Jersey; 28 counties in Pennsylvania. It was in force for 9 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 14, 2021, 2:06 PM EDT (18:06 UTC)
- Expired
- Jun 14, 2021, 11:00 PM EDT
- In force
- 9 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 41 counties
Burlington County, NJ, Camden 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, Sussex County, NJ, Warren County, NJ, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Monroe 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, Sullivan County, PA, Union County, PA, York County, PA
The radar
The State College radar (KCCX), 159 km from the middle of the area, began a volume at 18:11 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
- 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
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
17 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 14, 2:33 PM EDT | Severe Thunderstorm Warning | CTP | Clinton, Lycoming, Union | 57 min |
| Jun 14, 3:18 PM EDT | Severe Thunderstorm Warning | CTP | Columbia, Lycoming, Montour, Northumberland, Union | 57 min |
| Jun 14, 4:10 PM EDT | Severe Thunderstorm Warning | CTP | Columbia, Schuylkill | 50 min |
| Jun 14, 4:11 PM EDT | Severe Thunderstorm Warning | BGM | Luzerne | 49 min |
| Jun 14, 4:15 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Carbon, Lehigh, Monroe, Northampton | 60 min |
| Jun 14, 6:48 PM EDT | Severe Thunderstorm Warning | PHI | Morris, Somerset, Sussex | 42 min |
| Jun 14, 7:02 PM EDT | Severe Thunderstorm Warning | PHI | Mercer, Middlesex, Monmouth | 43 min |
| Jun 14, 7:55 PM EDT | Severe Thunderstorm Warning | PHI | Middlesex, Morris, Somerset | 32 min |
| Jun 14, 7:55 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Chester, Delaware, Montgomery, Philadelphia | 50 min |
| Jun 14, 8:08 PM EDT | Severe Thunderstorm Warning | PHI | Hunterdon, Mercer, Middlesex, Monmouth, Somerset | 52 min |
| Jun 14, 8:34 PM EDT | Severe Thunderstorm Warning | PHI | Burlington, Camden, Gloucester | 41 min |
| Jun 14, 8:55 PM EDT | Severe Thunderstorm Warning | PHI | Gloucester | 50 min |
| Jun 14, 9:11 PM EDT | Severe Thunderstorm Warning | PHI | Burlington, Camden, Gloucester, Mercer, Middlesex, Monmouth and 1 more | 49 min |
| Jun 14, 9:17 PM EDT | Flash Flood Warning | PHI | Burlington, Camden | 3 hr |
| Jun 14, 9:29 PM EDT | Severe Thunderstorm Warning | PHI | Burlington, Camden, Gloucester | 46 min |
| Jun 14, 9:58 PM EDT | Severe Thunderstorm Warning | PHI | Monmouth | 32 min |
| Jun 14, 10:07 PM EDT | Severe Thunderstorm Warning | PHI | Atlantic, Burlington, Camden, Gloucester, Ocean | 53 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, 6.1 hours before the alert went out and 223 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
- 2 J/kg
- Mixed-layer CIN
- -447 J/kg
- Mixed-layer LCL
- 1007 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 31 m²/s²
- 0-3 km storm-relative helicity
- 87 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
684 WWUS20 KWNS 141803 SEL0 SPC WW 141803 DEZ000-NJZ000-PAZ000-CWZ000-150100- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 270 NWS Storm Prediction Center Norman OK 205 PM EDT Mon Jun 14 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northern Delaware New Jersey Eastern Pennsylvania Coastal Waters * Effective this Monday afternoon and evening from 205 PM until 900 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...A cluster with splitting cells should evolve east from western Pennsylvania. Additional cells may form near the Delaware Valley, before spreading east towards the New Jersey coast. The severe thunderstorm watch area is approximately along and 60 statute miles north and south of a line from 45 miles northwest of Harrisburg PA to 20 miles north northeast of Lakehurst NJ. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 269... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 29035. ...Grams
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 14, 1:40 PM EDT | Mesoscale Discussion | SPC | Burlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 3 more | 3 hr |
| Jun 14, 6:18 PM EDT | Mesoscale Discussion | SPC | Atlantic, Bergen, Burlington, Camden, Cumberland, Essex and 14 more | 117 min |
| Jun 14, 6:41 PM EDT | Mesoscale Discussion | SPC | Cumberland, Gloucester, Salem | 2 hr |
| Jun 14, 7:29 PM EDT | Severe Thunderstorm Watch | SPC | Atlantic, Cape May, Cumberland | 6 hr |
| Jun 14, 11:31 AM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Beaver, Bedford, Blair, Butler and 22 more | 89 min |
| Jun 14, 11:46 AM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Armstrong, Beaver, Bedford, Blair, Butler and 20 more | 6 hr |
| Jun 14, 2:48 PM EDT | Mesoscale Discussion | SPC | Susquehanna | 2 hr |
| Jun 14, 3:25 PM EDT | Mesoscale Discussion | SPC | Fayette, Greene, Somerset, Washington, Westmoreland | 95 min |
Nearby
Severe Thunderstorm Watches in Pennsylvania, 2021Severe Thunderstorm Watches in New Jersey, 2021Every severe thunderstorm watch in 2021
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.